Replace XXXReturn with Result<XXXSuccess, XXXError>

... in function signatures.

These breaking changes aim at improving usability by allowing users
to take advantage of Rust error management features sur as `ok_or`,
`map_err`, `expect` and the `?` operator. See the `examples` and
`tutorials` to get an idea of the impacts.

Gir_Gst.toml

@@ -386,6 +386,26 @@ status = "generate"
         [object.function.return]
         bool_return_is_error = "Failed to sync state with parent"
 
+    [[object.function]]
+    name = "change_state"
+    # Use Result<StateChangeSuccess, StateChangeError>
+    ignore = true
+
+    [[object.function]]
+    name = "continue_state"
+    # Use Result<StateChangeSuccess, StateChangeError>
+    ignore = true
+
+    [[object.function]]
+    name = "get_state"
+    # Use Result<StateChangeSuccess, StateChangeError>
+    ignore = true
+
+    [[object.function]]
+    name = "set_state"
+    # Use Result<StateChangeSuccess, StateChangeError>
+    ignore = true
+
     [[object.function]]
     name = "query"
     # correct mutability
@@ -645,6 +665,11 @@ status = "generate"
     # Buffer can be NULL
     ignore = true
 
+    [[object.function]]
+    name = "get_last_flow_return"
+    # Use Result<FlowSuccess, FlowError>
+    ignore = true
+
     [[object.function]]
     name = "query"
     # Correct mutability
@@ -685,6 +710,21 @@ status = "generate"
     # Pass by value
     ignore = true
 
+    [[object.function]]
+    name = "link"
+    # Use Result<PadLinkSuccess, PadLinkError>
+    ignore = true
+
+    [[object.function]]
+    name = "link_full"
+    # Use Result<PadLinkSuccess, PadLinkError>
+    ignore = true
+
+    [[object.function]]
+    name = "store_sticky_event"
+    # Use Result<FlowSuccess, FlowError>
+    ignore = true
+
     [[object.function]]
     name = "new_from_static_template"
     # Correct mutability

Gir_GstApp.toml

@@ -57,6 +57,16 @@ trait = false
     # Action signal
     ignore = true
 
+    [[object.signal]]
+    name = "new-sample"
+    # Use Result<FlowSuccess, FlowError>
+    ignore = true
+
+    [[object.signal]]
+    name = "new-preroll"
+    # Use Result<FlowSuccess, FlowError>
+    ignore = true
+
     [[object.function]]
     name = "set_caps"
         [[object.function.parameter]]
@@ -98,6 +108,16 @@ trait = false
     # Action signal
     ignore = true
 
+    [[object.function]]
+    name = "end_of_stream"
+    # Use Result<FlowSuccess, FlowError>
+    ignore = true
+
+    [[object.function]]
+    name = "push_sample"
+    # Use Result<FlowSuccess, FlowError>
+    ignore = true
+
     [[object.function]]
     name = "set_latency"
     # ClockTime

Gir_GstBase.toml

@@ -77,16 +77,41 @@ name = "GstBase.BaseSink"
 subclassing = true
 status = "generate"
 
+    [[object.function]]
+    name = "wait"
+    # Use Result<FlowSuccess, FlowError>
+    ignore = true
+
+    [[object.function]]
+    name = "wait_preroll"
+    # Use Result<FlowSuccess, FlowError>
+    ignore = true
+
 [[object]]
 name = "GstBase.BaseSrc"
 subclassing = true
 status = "generate"
 
+    [[object.function]]
+    name = "start_complete"
+    # Use Result<FlowSuccess, FlowError>
+    ignore = true
+
+    [[object.function]]
+    name = "start_wait"
+    # Use Result<FlowSuccess, FlowError>
+    ignore = true
+
     [[object.function]]
     name = "submit_buffer_list"
     # Pass by value, to be added manually
     ignore = true
 
+    [[object.function]]
+    name = "wait_playing"
+    # Use Result<FlowSuccess, FlowError>
+    ignore = true
+
 [[object]]
 name = "GstBase.BaseTransform"
 subclassing = true

Gir_GstRtspServer.toml

@@ -122,6 +122,16 @@ status = "generate"
 name = "GstRtspServer.RTSPStream"
 status = "generate"
 
+    [[object.function]]
+    name = "recv_rtcp"
+    # Use Result<FlowSuccess, FlowError>
+    ignore = true
+
+    [[object.function]]
+    name = "recv_rtp"
+    # Use Result<FlowSuccess, FlowError>
+    ignore = true
+
     [[object.function]]
     name = "query_position"
     ignore = true
@@ -160,6 +170,11 @@ name = "GstRtspServer.RTSPStreamTransport"
 status = "generate"
 concurrency = "none"
 
+    [[object.function]]
+    name = "recv_data"
+    # Use Result<FlowSuccess, FlowError>
+    ignore = true
+
     [[object.function]]
     name = "send_rtcp"
         [object.function.return]

examples/src/bin/appsink.rs

@@ -87,22 +87,16 @@ fn create_pipeline() -> Result<gst::Pipeline, Error> {
             // Add a handler to the "new-sample" signal.
             .new_sample(|appsink| {
                 // Pull the sample in question out of the appsink's buffer.
-                let sample = match appsink.pull_sample() {
-                    None => return gst::FlowReturn::Eos,
-                    Some(sample) => sample,
-                };
-
-                let buffer = if let Some(buffer) = sample.get_buffer() {
-                    buffer
-                } else {
+                let sample = appsink.pull_sample().ok_or(gst::FlowError::Eos)?;
+                let buffer = sample.get_buffer().ok_or_else(|| {
                     gst_element_error!(
                         appsink,
                         gst::ResourceError::Failed,
                         ("Failed to get buffer from appsink")
                     );
 
-                    return gst::FlowReturn::Error;
-                };
+                    gst::FlowError::Error
+                })?;
 
                 // At this point, buffer is only a reference to an existing memory region somewhere.
                 // When we want to access its content, we have to map it while requesting the required
@@ -111,32 +105,28 @@ fn create_pipeline() -> Result<gst::Pipeline, Error> {
                 // on the machine's main memory itself, but rather in the GPU's memory.
                 // So mapping the buffer makes the underlying memory region accessible to us.
                 // See: https://gstreamer.freedesktop.org/documentation/plugin-development/advanced/allocation.html
-                let map = if let Some(map) = buffer.map_readable() {
-                    map
-                } else {
+                let map = buffer.map_readable().ok_or_else(|| {
                     gst_element_error!(
                         appsink,
                         gst::ResourceError::Failed,
                         ("Failed to map buffer readable")
                     );
 
-                    return gst::FlowReturn::Error;
-                };
+                    gst::FlowError::Error
+                })?;
 
                 // We know what format the data in the memory region has, since we requested
                 // it by setting the appsink's caps. So what we do here is interpret the
                 // memory region we mapped as an array of signed 16 bit integers.
-                let samples = if let Ok(samples) = map.as_slice_of::<i16>() {
-                    samples
-                } else {
+                let samples = map.as_slice_of::<i16>().map_err(|_| {
                     gst_element_error!(
                         appsink,
                         gst::ResourceError::Failed,
                         ("Failed to interprete buffer as S16 PCM")
                     );
 
-                    return gst::FlowReturn::Error;
-                };
+                    gst::FlowError::Error
+                })?;
 
                 // For buffer (= chunk of samples), we calculate the root mean square:
                 // (https://en.wikipedia.org/wiki/Root_mean_square)
@@ -150,7 +140,7 @@ fn create_pipeline() -> Result<gst::Pipeline, Error> {
                 let rms = (sum / (samples.len() as f64)).sqrt();
                 println!("rms: {}", rms);
 
-                gst::FlowReturn::Ok
+                Ok(gst::FlowSuccess::Ok)
             })
             .build(),
     );
@@ -159,7 +149,7 @@ fn create_pipeline() -> Result<gst::Pipeline, Error> {
 }
 
 fn main_loop(pipeline: gst::Pipeline) -> Result<(), Error> {
-    pipeline.set_state(gst::State::Playing).into_result()?;
+    pipeline.set_state(gst::State::Playing)?;
 
     let bus = pipeline
         .get_bus()
@@ -171,7 +161,7 @@ fn main_loop(pipeline: gst::Pipeline) -> Result<(), Error> {
         match msg.view() {
             MessageView::Eos(..) => break,
             MessageView::Error(err) => {
-                pipeline.set_state(gst::State::Null).into_result()?;
+                pipeline.set_state(gst::State::Null)?;
                 Err(ErrorMessage {
                     src: msg
                         .get_src()
@@ -186,7 +176,7 @@ fn main_loop(pipeline: gst::Pipeline) -> Result<(), Error> {
         }
     }
 
-    pipeline.set_state(gst::State::Null).into_result()?;
+    pipeline.set_state(gst::State::Null)?;
 
     Ok(())
 }

examples/src/bin/appsrc.rs

@@ -141,7 +141,7 @@ fn create_pipeline() -> Result<gst::Pipeline, Error> {
 }
 
 fn main_loop(pipeline: gst::Pipeline) -> Result<(), Error> {
-    pipeline.set_state(gst::State::Playing).into_result()?;
+    pipeline.set_state(gst::State::Playing)?;
 
     let bus = pipeline
         .get_bus()
@@ -153,7 +153,7 @@ fn main_loop(pipeline: gst::Pipeline) -> Result<(), Error> {
         match msg.view() {
             MessageView::Eos(..) => break,
             MessageView::Error(err) => {
-                pipeline.set_state(gst::State::Null).into_result()?;
+                pipeline.set_state(gst::State::Null)?;
                 Err(ErrorMessage {
                     src: msg
                         .get_src()
@@ -168,7 +168,7 @@ fn main_loop(pipeline: gst::Pipeline) -> Result<(), Error> {
         }
     }
 
-    pipeline.set_state(gst::State::Null).into_result()?;
+    pipeline.set_state(gst::State::Null)?;
 
     Ok(())
 }

examples/src/bin/decodebin.rs

@@ -181,7 +181,7 @@ fn example_main() -> Result<(), Error> {
                 // Get the queue element's sink pad and link the decodebin's newly created
                 // src pad for the audio stream to it.
                 let sink_pad = queue.get_static_pad("sink").expect("queue has no sinkpad");
-                src_pad.link(&sink_pad).into_result()?;
+                src_pad.link(&sink_pad)?;
             } else if is_video {
                 // decodebin found a raw videostream, so we build the follow-up pipeline to
                 // display it using the autovideosink.
@@ -205,7 +205,7 @@ fn example_main() -> Result<(), Error> {
                 // Get the queue element's sink pad and link the decodebin's newly created
                 // src pad for the video stream to it.
                 let sink_pad = queue.get_static_pad("sink").expect("queue has no sinkpad");
-                src_pad.link(&sink_pad).into_result()?;
+                src_pad.link(&sink_pad)?;
             }
 
             Ok(())
@@ -243,7 +243,7 @@ fn example_main() -> Result<(), Error> {
         }
     });
 
-    pipeline.set_state(gst::State::Playing).into_result()?;
+    pipeline.set_state(gst::State::Playing)?;
 
     let bus = pipeline
         .get_bus()
@@ -259,7 +259,7 @@ fn example_main() -> Result<(), Error> {
         match msg.view() {
             MessageView::Eos(..) => break,
             MessageView::Error(err) => {
-                pipeline.set_state(gst::State::Null).into_result()?;
+                pipeline.set_state(gst::State::Null)?;
 
                 #[cfg(feature = "v1_10")]
                 {
@@ -313,7 +313,7 @@ fn example_main() -> Result<(), Error> {
         }
     }
 
-    pipeline.set_state(gst::State::Null).into_result()?;
+    pipeline.set_state(gst::State::Null)?;
 
     Ok(())
 }

examples/src/bin/encodebin.rs

@@ -210,7 +210,7 @@ fn example_main() -> Result<(), Error> {
                 let src_pad = resample
                     .get_static_pad("src")
                     .expect("resample has no srcpad");
-                src_pad.link(&enc_sink_pad).into_result()?;
+                src_pad.link(&enc_sink_pad)?;
 
                 for e in elements {
                     e.sync_state_with_parent()?;
@@ -219,7 +219,7 @@ fn example_main() -> Result<(), Error> {
                 // Get the queue element's sink pad and link the decodebin's newly created
                 // src pad for the audio stream to it.
                 let sink_pad = queue.get_static_pad("sink").expect("queue has no sinkpad");
-                dbin_src_pad.link(&sink_pad).into_result()?;
+                dbin_src_pad.link(&sink_pad)?;
             } else if is_video {
                 let queue =
                     gst::ElementFactory::make("queue", None).ok_or(MissingElement("queue"))?;
@@ -243,7 +243,7 @@ fn example_main() -> Result<(), Error> {
                 let src_pad = scale
                     .get_static_pad("src")
                     .expect("videoscale has no srcpad");
-                src_pad.link(&enc_sink_pad).into_result()?;
+                src_pad.link(&enc_sink_pad)?;
 
                 for e in elements {
                     e.sync_state_with_parent()?
@@ -252,7 +252,7 @@ fn example_main() -> Result<(), Error> {
                 // Get the queue element's sink pad and link the decodebin's newly created
                 // src pad for the video stream to it.
                 let sink_pad = queue.get_static_pad("sink").expect("queue has no sinkpad");
-                dbin_src_pad.link(&sink_pad).into_result()?;
+                dbin_src_pad.link(&sink_pad)?;
             }
 
             Ok(())
@@ -280,7 +280,7 @@ fn example_main() -> Result<(), Error> {
         }
     });
 
-    pipeline.set_state(gst::State::Playing).into_result()?;
+    pipeline.set_state(gst::State::Playing)?;
 
     let bus = pipeline
         .get_bus()
@@ -292,7 +292,7 @@ fn example_main() -> Result<(), Error> {
         match msg.view() {
             MessageView::Eos(..) => break,
             MessageView::Error(err) => {
-                pipeline.set_state(gst::State::Null).into_result()?;
+                pipeline.set_state(gst::State::Null)?;
 
                 #[cfg(feature = "v1_10")]
                 {
@@ -342,7 +342,7 @@ fn example_main() -> Result<(), Error> {
         }
     }
 
-    pipeline.set_state(gst::State::Null).into_result()?;
+    pipeline.set_state(gst::State::Null)?;
 
     Ok(())
 }

examples/src/bin/events.rs

@@ -36,8 +36,9 @@ fn example_main() {
     let pipeline = gst::parse_launch("audiotestsrc ! fakesink").unwrap();
     let bus = pipeline.get_bus().unwrap();
 
-    let ret = pipeline.set_state(gst::State::Playing);
-    assert_ne!(ret, gst::StateChangeReturn::Failure);
+    pipeline
+        .set_state(gst::State::Playing)
+        .expect("Unable to set the pipeline to the `Playing` state");
 
     // Need to move a new reference into the closure.
     // !!ATTENTION!!:
@@ -122,8 +123,9 @@ fn example_main() {
     // (see above for how to do this).
     main_loop.run();
 
-    let ret = pipeline.set_state(gst::State::Null);
-    assert_ne!(ret, gst::StateChangeReturn::Failure);
+    pipeline
+        .set_state(gst::State::Null)
+        .expect("Unable to set the pipeline to the `Null` state");
 
     // Remove the watch function from the bus.
     // Again: There can always only be one watch function.

examples/src/bin/futures.rs

@@ -25,8 +25,9 @@ fn example_main() {
     let pipeline = gst::parse_launch(&pipeline_str).unwrap();
     let bus = pipeline.get_bus().unwrap();
 
-    let ret = pipeline.set_state(gst::State::Playing);
-    assert_ne!(ret, gst::StateChangeReturn::Failure);
+    pipeline
+        .set_state(gst::State::Playing)
+        .expect("Unable to set the pipeline to the `Playing` state");
 
     // BusStream implements the Stream trait, but Stream::for_each is
     // calling a closure for each item and returns a Future that resolves
@@ -65,8 +66,9 @@ fn example_main() {
     // Synchronously wait on the future we created above.
     let _ = block_on(messages);
 
-    let ret = pipeline.set_state(gst::State::Null);
-    assert_ne!(ret, gst::StateChangeReturn::Failure);
+    pipeline
+        .set_state(gst::State::Null)
+        .expect("Unable to set the pipeline to the `Null` state");
 }
 
 fn main() {

examples/src/bin/ges.rs

@@ -100,8 +100,9 @@ fn main_loop(uri: &str) -> Result<(), glib::BoolError> {
     clip.set_inpoint(duration / 2);
     clip.set_duration(duration / 4);
 
-    let ret = pipeline.set_state(gst::State::Playing);
-    assert_ne!(ret, gst::StateChangeReturn::Failure);
+    pipeline
+        .set_state(gst::State::Playing)
+        .expect("Unable to set the pipeline to the `Playing` state");
 
     let bus = pipeline.get_bus().unwrap();
     for msg in bus.iter_timed(gst::CLOCK_TIME_NONE) {
@@ -122,8 +123,9 @@ fn main_loop(uri: &str) -> Result<(), glib::BoolError> {
         }
     }
 
-    let ret = pipeline.set_state(gst::State::Null);
-    assert_ne!(ret, gst::StateChangeReturn::Failure);
+    pipeline
+        .set_state(gst::State::Null)
+        .expect("Unable to set the pipeline to the `Null` state");
 
     Ok(())
 }

examples/src/bin/glib-futures.rs

@@ -21,8 +21,9 @@ fn example_main() {
     let pipeline = gst::parse_launch(&pipeline_str).unwrap();
     let bus = pipeline.get_bus().unwrap();
 
-    let ret = pipeline.set_state(gst::State::Playing);
-    assert_ne!(ret, gst::StateChangeReturn::Failure);
+    pipeline
+        .set_state(gst::State::Playing)
+        .expect("Unable to set the pipeline to the `Playing` state");
 
     let messages = gst::BusStream::new(&bus)
         .for_each(|msg| {
@@ -52,8 +53,9 @@ fn example_main() {
 
     let _ = ctx.block_on(messages);
 
-    let ret = pipeline.set_state(gst::State::Null);
-    assert_ne!(ret, gst::StateChangeReturn::Failure);
+    pipeline
+        .set_state(gst::State::Null)
+        .expect("Unable to set the pipeline to the `Null` state");
 }
 
 fn main() {

examples/src/bin/glupload.rs

@@ -428,34 +428,42 @@ impl App {
         self.appsink.set_callbacks(
             gst_app::AppSinkCallbacks::new()
                 .new_sample(move |appsink| {
-                    let sample = match appsink.pull_sample() {
-                        None => return gst::FlowReturn::Eos,
-                        Some(sample) => sample,
-                    };
+                    let sample = appsink.pull_sample().ok_or(gst::FlowError::Eos)?;
 
-                    let buffer = sample.get_buffer();
-                    let info = sample
-                        .get_caps()
-                        .and_then(|caps| gst_video::VideoInfo::from_caps(caps.as_ref()));
-                    if buffer.is_none() || info.is_none() {
+                    let _buffer = sample.get_buffer().ok_or_else(|| {
                         gst_element_error!(
                             appsink,
                             gst::ResourceError::Failed,
                             ("Failed to get buffer from appsink")
                         );
 
-                        return gst::FlowReturn::Error;
-                    };
+                        gst::FlowError::Error
+                    })?;
 
-                    match sender_clone.lock().unwrap().send(sample) {
-                        Ok(_) => return gst::FlowReturn::Ok,
-                        Err(_) => return gst::FlowReturn::Error,
-                    }
+                    let _info = sample
+                        .get_caps()
+                        .and_then(|caps| gst_video::VideoInfo::from_caps(caps.as_ref()))
+                        .ok_or_else(|| {
+                            gst_element_error!(
+                                appsink,
+                                gst::ResourceError::Failed,
+                                ("Failed to get video info from sample")
+                            );
+
+                            gst::FlowError::Error
+                        })?;
+
+                    sender_clone
+                        .lock()
+                        .unwrap()
+                        .send(sample)
+                        .map(|_| gst::FlowSuccess::Ok)
+                        .map_err(|_| gst::FlowError::Error)
                 })
                 .build(),
         );
 
-        self.pipeline.set_state(gst::State::Playing).into_result()?;
+        self.pipeline.set_state(gst::State::Playing)?;
 
         Ok((bus_handler, receiver))
     }
@@ -576,7 +584,7 @@ fn main_loop(mut app: App) -> Result<(), Error> {
 
     app.pipeline.send_event(gst::Event::new_eos().build());
     bus_handler.join().expect("Could join bus handler thread");
-    app.pipeline.set_state(gst::State::Null).into_result()?;
+    app.pipeline.set_state(gst::State::Null)?;
 
     Ok(())
 }

examples/src/bin/gtksink.rs

@@ -108,8 +108,9 @@ fn create_ui(app: &gtk::Application) {
 
     let bus = pipeline.get_bus().unwrap();
 
-    let ret = pipeline.set_state(gst::State::Playing);
-    assert_ne!(ret, gst::StateChangeReturn::Failure);
+    pipeline
+        .set_state(gst::State::Playing)
+        .expect("Unable to set the pipeline to the `Playing` state");
 
     let app_weak = glib::SendWeakRef::from(app.downgrade());
     bus.add_watch(move |_, msg| {
@@ -141,8 +142,9 @@ fn create_ui(app: &gtk::Application) {
     // destroyed once the app is destroyed
     let timeout_id = RefCell::new(Some(timeout_id));
     app.connect_shutdown(move |_| {
-        let ret = pipeline.set_state(gst::State::Null);
-        assert_ne!(ret, gst::StateChangeReturn::Failure);
+        pipeline
+            .set_state(gst::State::Null)
+            .expect("Unable to set the pipeline to the `Null` state");
 
         bus.remove_watch();
         if let Some(timeout_id) = timeout_id.borrow_mut().take() {

examples/src/bin/gtkvideooverlay.rs

@@ -211,8 +211,9 @@ fn create_ui(app: &gtk::Application) {
 
     let bus = pipeline.get_bus().unwrap();
 
-    let ret = pipeline.set_state(gst::State::Playing);
-    assert_ne!(ret, gst::StateChangeReturn::Failure);
+    pipeline
+        .set_state(gst::State::Playing)
+        .expect("Unable to set the pipeline to the `Playing` state");
 
     let app_weak = glib::SendWeakRef::from(app.downgrade());
     bus.add_watch(move |_, msg| {
@@ -244,8 +245,9 @@ fn create_ui(app: &gtk::Application) {
     // destroyed once the app is destroyed
     let timeout_id = RefCell::new(Some(timeout_id));
     app.connect_shutdown(move |_| {
-        let ret = pipeline.set_state(gst::State::Null);
-        assert_ne!(ret, gst::StateChangeReturn::Failure);
+        pipeline
+            .set_state(gst::State::Null)
+            .expect("Unable to set the pipeline to the `Null` state");
 
         bus.remove_watch();
         if let Some(timeout_id) = timeout_id.borrow_mut().take() {

examples/src/bin/launch.rs

@@ -43,8 +43,9 @@ fn example_main() {
         };
     let bus = pipeline.get_bus().unwrap();
 
-    let ret = pipeline.set_state(gst::State::Playing);
-    assert_ne!(ret, gst::StateChangeReturn::Failure);
+    pipeline
+        .set_state(gst::State::Playing)
+        .expect("Unable to set the pipeline to the `Playing` state");
 
     for msg in bus.iter_timed(gst::CLOCK_TIME_NONE) {
         use gst::MessageView;
@@ -64,8 +65,9 @@ fn example_main() {
         }
     }
 
-    let ret = pipeline.set_state(gst::State::Null);
-    assert_ne!(ret, gst::StateChangeReturn::Failure);
+    pipeline
+        .set_state(gst::State::Null)
+        .expect("Unable to set the pipeline to the `Null` state");
 }
 
 fn main() {

examples/src/bin/launch_glib_main.rs

@@ -30,8 +30,9 @@ fn example_main() {
     let pipeline = gst::parse_launch(&pipeline_str).unwrap();
     let bus = pipeline.get_bus().unwrap();
 
-    let ret = pipeline.set_state(gst::State::Playing);
-    assert_ne!(ret, gst::StateChangeReturn::Failure);
+    pipeline
+        .set_state(gst::State::Playing)
+        .expect("Unable to set the pipeline to the `Playing` state");
 
     let main_loop_clone = main_loop.clone();
 
@@ -60,8 +61,9 @@ fn example_main() {
 
     main_loop.run();
 
-    let ret = pipeline.set_state(gst::State::Null);
-    assert_ne!(ret, gst::StateChangeReturn::Failure);
+    pipeline
+        .set_state(gst::State::Null)
+        .expect("Unable to set the pipeline to the `Null` state");
 
     // Here we remove the bus watch we added above. This avoids a memory leak, that might
     // otherwise happen because we moved a strong reference (clone of main_loop) into the

examples/src/bin/pad_probes.rs

@@ -75,8 +75,9 @@ fn example_main() {
         gst::PadProbeReturn::Ok
     });
 
-    let ret = pipeline.set_state(gst::State::Playing);
-    assert_ne!(ret, gst::StateChangeReturn::Failure);
+    pipeline
+        .set_state(gst::State::Playing)
+        .expect("Unable to set the pipeline to the `Playing` state");
 
     let bus = pipeline.get_bus().unwrap();
     for msg in bus.iter_timed(gst::CLOCK_TIME_NONE) {
@@ -97,8 +98,9 @@ fn example_main() {
         }
     }
 
-    let ret = pipeline.set_state(gst::State::Null);
-    assert_ne!(ret, gst::StateChangeReturn::Failure);
+    pipeline
+        .set_state(gst::State::Null)
+        .expect("Unable to set the pipeline to the `Null` state");
 }
 
 fn main() {

examples/src/bin/pango-cairo.rs

@@ -237,7 +237,7 @@ fn create_pipeline() -> Result<gst::Pipeline, Error> {
 }
 
 fn main_loop(pipeline: gst::Pipeline) -> Result<(), Error> {
-    pipeline.set_state(gst::State::Playing).into_result()?;
+    pipeline.set_state(gst::State::Playing)?;
 
     let bus = pipeline
         .get_bus()
@@ -249,7 +249,7 @@ fn main_loop(pipeline: gst::Pipeline) -> Result<(), Error> {
         match msg.view() {
             MessageView::Eos(..) => break,
             MessageView::Error(err) => {
-                pipeline.set_state(gst::State::Null).into_result()?;
+                pipeline.set_state(gst::State::Null)?;
                 Err(ErrorMessage {
                     src: msg
                         .get_src()
@@ -264,7 +264,7 @@ fn main_loop(pipeline: gst::Pipeline) -> Result<(), Error> {
         }
     }
 
-    pipeline.set_state(gst::State::Null).into_result()?;
+    pipeline.set_state(gst::State::Null)?;
 
     Ok(())
 }

examples/src/bin/playbin.rs

@@ -103,8 +103,9 @@ fn example_main() {
     // created from an element factory.
     let bus = playbin.get_bus().unwrap();
 
-    let ret = playbin.set_state(gst::State::Playing);
-    assert_ne!(ret, gst::StateChangeReturn::Failure);
+    playbin
+        .set_state(gst::State::Playing)
+        .expect("Unable to set the pipeline to the `Playing` state");
 
     for msg in bus.iter_timed(gst::CLOCK_TIME_NONE) {
         use gst::MessageView;
@@ -124,8 +125,9 @@ fn example_main() {
         }
     }
 
-    let ret = playbin.set_state(gst::State::Null);
-    assert_ne!(ret, gst::StateChangeReturn::Failure);
+    playbin
+        .set_state(gst::State::Null)
+        .expect("Unable to set the pipeline to the `Null` state");
 }
 
 fn main() {

examples/src/bin/queries.rs

@@ -34,8 +34,9 @@ fn example_main() {
     let pipeline = gst::parse_launch(&pipeline_str).unwrap();
     let bus = pipeline.get_bus().unwrap();
 
-    let ret = pipeline.set_state(gst::State::Playing);
-    assert_ne!(ret, gst::StateChangeReturn::Failure);
+    pipeline
+        .set_state(gst::State::Playing)
+        .expect("Unable to set the pipeline to the `Playing` state");
 
     // Need to move a new reference into the closure.
     // !!ATTENTION!!:
@@ -119,8 +120,9 @@ fn example_main() {
 
     main_loop.run();
 
-    let ret = pipeline.set_state(gst::State::Null);
-    assert_ne!(ret, gst::StateChangeReturn::Failure);
+    pipeline
+        .set_state(gst::State::Null)
+        .expect("Unable to set the pipeline to the `Null` state");
 
     bus.remove_watch();
     glib::source_remove(timeout_id);

examples/src/bin/rtpfecclient.rs

@@ -84,7 +84,7 @@ fn connect_rtpbin_srcpad(src_pad: &gst::Pad, sink: &gst::Element) -> Result<(),
     match pt {
         96 => {
             let sinkpad = get_static_pad(sink, "sink")?;
-            src_pad.link(&sinkpad).into_result()?;
+            src_pad.link(&sinkpad)?;
             Ok(())
         }
         _ => Err(Error::from(UnknownPT(pt))),
@@ -208,7 +208,7 @@ fn example_main() -> Result<(), Error> {
 
     let srcpad = get_static_pad(&netsim, "src")?;
     let sinkpad = get_request_pad(&rtpbin, "recv_rtp_sink_0")?;
-    srcpad.link(&sinkpad).into_result()?;
+    srcpad.link(&sinkpad)?;
 
     let depay_weak = depay.downgrade();
     rtpbin.connect_pad_added(move |rtpbin, src_pad| {
@@ -246,8 +246,9 @@ fn example_main() -> Result<(), Error> {
         .get_bus()
         .expect("Pipeline without bus. Shouldn't happen!");
 
-    let ret = pipeline.set_state(gst::State::Playing);
-    assert_ne!(ret, gst::StateChangeReturn::Failure);
+    pipeline
+        .set_state(gst::State::Playing)
+        .expect("Unable to set the pipeline to the `Playing` state");
 
     for msg in bus.iter_timed(gst::CLOCK_TIME_NONE) {
         use gst::MessageView;
@@ -255,8 +256,9 @@ fn example_main() -> Result<(), Error> {
         match msg.view() {
             MessageView::Eos(..) => break,
             MessageView::Error(err) => {
-                let ret = pipeline.set_state(gst::State::Null);
-                assert_ne!(ret, gst::StateChangeReturn::Failure);
+                pipeline
+                    .set_state(gst::State::Null)
+                    .expect("Unable to set the pipeline to the `Null` state");
 
                 return Err(ErrorMessage {
                     src: msg
@@ -286,8 +288,9 @@ fn example_main() -> Result<(), Error> {
         }
     }
 
-    let ret = pipeline.set_state(gst::State::Null);
-    assert_ne!(ret, gst::StateChangeReturn::Failure);
+    pipeline
+        .set_state(gst::State::Null)
+        .expect("Unable to set the pipeline to the `Null` state");
 
     Ok(())
 }

examples/src/bin/rtpfecserver.rs

@@ -74,7 +74,7 @@ fn get_request_pad(element: &gst::Element, pad_name: &'static str) -> Result<gst
 
 fn connect_decodebin_pad(src_pad: &gst::Pad, sink: &gst::Element) -> Result<(), Error> {
     let sinkpad = get_static_pad(&sink, "sink")?;
-    src_pad.link(&sinkpad).into_result()?;
+    src_pad.link(&sinkpad)?;
 
     Ok(())
 }
@@ -137,11 +137,11 @@ fn example_main() -> Result<(), Error> {
 
     let srcpad = get_static_pad(&q2, "src")?;
     let sinkpad = get_request_pad(&rtpbin, "send_rtp_sink_0")?;
-    srcpad.link(&sinkpad).into_result()?;
+    srcpad.link(&sinkpad)?;
 
     let srcpad = get_static_pad(&rtpbin, "send_rtp_src_0")?;
     let sinkpad = get_static_pad(&sink, "sink")?;
-    srcpad.link(&sinkpad).into_result()?;
+    srcpad.link(&sinkpad)?;
 
     let convclone = conv.clone();
     src.connect_pad_added(move |decodebin, src_pad| {
@@ -177,8 +177,9 @@ fn example_main() -> Result<(), Error> {
         .get_bus()
         .expect("Pipeline without bus. Shouldn't happen!");
 
-    let ret = pipeline.set_state(gst::State::Playing);
-    assert_ne!(ret, gst::StateChangeReturn::Failure);
+    pipeline
+        .set_state(gst::State::Playing)
+        .expect("Unable to set the pipeline to the `Playing` state");
 
     for msg in bus.iter_timed(gst::CLOCK_TIME_NONE) {
         use gst::MessageView;
@@ -186,8 +187,9 @@ fn example_main() -> Result<(), Error> {
         match msg.view() {
             MessageView::Eos(..) => break,
             MessageView::Error(err) => {
-                let ret = pipeline.set_state(gst::State::Null);
-                assert_ne!(ret, gst::StateChangeReturn::Failure);
+                pipeline
+                    .set_state(gst::State::Null)
+                    .expect("Unable to set the pipeline to the `Null` state");
 
                 return Err(ErrorMessage {
                     src: msg
@@ -217,8 +219,9 @@ fn example_main() -> Result<(), Error> {
         }
     }
 
-    let ret = pipeline.set_state(gst::State::Null);
-    assert_ne!(ret, gst::StateChangeReturn::Failure);
+    pipeline
+        .set_state(gst::State::Null)
+        .expect("Unable to set the pipeline to the `Null` state");
 
     Ok(())
 }

examples/src/bin/tagsetter.rs

@@ -94,7 +94,7 @@ fn example_main() -> Result<(), Error> {
 
     let bus = pipeline.get_bus().unwrap();
 
-    pipeline.set_state(gst::State::Playing).into_result()?;
+    pipeline.set_state(gst::State::Playing)?;
 
     for msg in bus.iter_timed(gst::CLOCK_TIME_NONE) {
         use gst::MessageView;
@@ -118,7 +118,7 @@ fn example_main() -> Result<(), Error> {
         }
     }
 
-    pipeline.set_state(gst::State::Null).into_result()?;
+    pipeline.set_state(gst::State::Null)?;
 
     Ok(())
 }

examples/src/bin/toc.rs

@@ -75,13 +75,14 @@ fn example_main() {
         }
 
         let sink_pad = queue.get_static_pad("sink").unwrap();
-        assert_eq!(src_pad.link(&sink_pad), gst::PadLinkReturn::Ok);
+        src_pad
+            .link(&sink_pad)
+            .expect("Unable to link src pad to sink pad");
     });
 
-    assert_ne!(
-        pipeline.set_state(gst::State::Paused),
-        gst::StateChangeReturn::Failure
-    );
+    pipeline
+        .set_state(gst::State::Paused)
+        .expect("Unable to set the pipeline to the `Paused` state");
 
     let bus = pipeline.get_bus().unwrap();
 
@@ -161,10 +162,9 @@ fn example_main() {
         }
     }
 
-    assert_ne!(
-        pipeline.set_state(gst::State::Null),
-        gst::StateChangeReturn::Failure
-    );
+    pipeline
+        .set_state(gst::State::Null)
+        .expect("Unable to set the pipeline to the `Null` state");
 }
 
 fn main() {

examples/src/bin/transmux.rs

@@ -153,7 +153,7 @@ fn example_main() -> Result<(), Error> {
         })
         .expect("Failed to register have-type signal of typefind");
 
-    pipeline.set_state(gst::State::Playing).into_result()?;
+    pipeline.set_state(gst::State::Playing)?;
 
     let bus = pipeline
         .get_bus()
@@ -165,7 +165,7 @@ fn example_main() -> Result<(), Error> {
         match msg.view() {
             MessageView::Eos(..) => break,
             MessageView::Error(err) => {
-                pipeline.set_state(gst::State::Null).into_result()?;
+                pipeline.set_state(gst::State::Null)?;
 
                 Err(ErrorMessage {
                     src: msg
@@ -191,7 +191,7 @@ fn example_main() -> Result<(), Error> {
         }
     }
 
-    pipeline.set_state(gst::State::Null).into_result()?;
+    pipeline.set_state(gst::State::Null)?;
 
     Ok(())
 }
@@ -209,7 +209,7 @@ fn handle_demux_pad_added(
         let queue_sink_pad = queue
             .get_request_pad("sink_%u")
             .expect("If this happened, something is terribly wrong");
-        demux_src_pad.link(&queue_sink_pad).into_result()?;
+        demux_src_pad.link(&queue_sink_pad)?;
         // Now that we requested a sink pad fitting our needs from the multiqueue,
         // the multiqueue automatically created a fitting src pad on the other side.
         // sink and src pad are linked internally, so we can iterate this internal link chain
@@ -224,7 +224,7 @@ fn handle_demux_pad_added(
         let muxer_sink_pad = muxer
             .get_compatible_pad(&queue_src_pad, None)
             .expect("Aww, you found a format that matroska doesn't support!");
-        queue_src_pad.link(&muxer_sink_pad).into_result()?;
+        queue_src_pad.link(&muxer_sink_pad)?;
 
         Ok(())
     };

gstreamer-app/src/app_sink.rs

@@ -7,19 +7,27 @@
 // except according to those terms.
 
 use ffi;
+use glib::signal::connect_raw;
+use glib::signal::SignalHandlerId;
 use glib::translate::*;
 use glib_ffi::gpointer;
 use gst;
 use gst_ffi;
+use std::boxed::Box as Box_;
 use std::cell::RefCell;
+use std::mem::transmute;
 use std::ptr;
 use AppSink;
 
 #[cfg_attr(feature = "cargo-clippy", allow(type_complexity))]
 pub struct AppSinkCallbacks {
     eos: Option<RefCell<Box<FnMut(&AppSink) + Send + 'static>>>,
-    new_preroll: Option<RefCell<Box<FnMut(&AppSink) -> gst::FlowReturn + Send + 'static>>>,
-    new_sample: Option<RefCell<Box<FnMut(&AppSink) -> gst::FlowReturn + Send + 'static>>>,
+    new_preroll: Option<
+        RefCell<Box<FnMut(&AppSink) -> Result<gst::FlowSuccess, gst::FlowError> + Send + 'static>>,
+    >,
+    new_sample: Option<
+        RefCell<Box<FnMut(&AppSink) -> Result<gst::FlowSuccess, gst::FlowError> + Send + 'static>>,
+    >,
     callbacks: ffi::GstAppSinkCallbacks,
 }
 
@@ -40,8 +48,12 @@ impl AppSinkCallbacks {
 #[cfg_attr(feature = "cargo-clippy", allow(type_complexity))]
 pub struct AppSinkCallbacksBuilder {
     eos: Option<RefCell<Box<FnMut(&AppSink) + Send + 'static>>>,
-    new_preroll: Option<RefCell<Box<FnMut(&AppSink) -> gst::FlowReturn + Send + 'static>>>,
-    new_sample: Option<RefCell<Box<FnMut(&AppSink) -> gst::FlowReturn + Send + 'static>>>,
+    new_preroll: Option<
+        RefCell<Box<FnMut(&AppSink) -> Result<gst::FlowSuccess, gst::FlowError> + Send + 'static>>,
+    >,
+    new_sample: Option<
+        RefCell<Box<FnMut(&AppSink) -> Result<gst::FlowSuccess, gst::FlowError> + Send + 'static>>,
+    >,
 }
 
 impl AppSinkCallbacksBuilder {
@@ -52,7 +64,9 @@ impl AppSinkCallbacksBuilder {
         }
     }
 
-    pub fn new_preroll<F: Fn(&AppSink) -> gst::FlowReturn + Send + Sync + 'static>(
+    pub fn new_preroll<
+        F: Fn(&AppSink) -> Result<gst::FlowSuccess, gst::FlowError> + Send + Sync + 'static,
+    >(
         self,
         new_preroll: F,
     ) -> Self {
@@ -62,7 +76,9 @@ impl AppSinkCallbacksBuilder {
         }
     }
 
-    pub fn new_sample<F: Fn(&AppSink) -> gst::FlowReturn + Send + Sync + 'static>(
+    pub fn new_sample<
+        F: Fn(&AppSink) -> Result<gst::FlowSuccess, gst::FlowError> + Send + Sync + 'static,
+    >(
         self,
         new_sample: F,
     ) -> Self {
@@ -119,7 +135,7 @@ unsafe extern "C" fn trampoline_new_preroll(
     let callbacks = &*(callbacks as *const AppSinkCallbacks);
 
     let ret = if let Some(ref new_preroll) = callbacks.new_preroll {
-        (&mut *new_preroll.borrow_mut())(&from_glib_borrow(appsink))
+        (&mut *new_preroll.borrow_mut())(&from_glib_borrow(appsink)).into()
     } else {
         gst::FlowReturn::Error
     };
@@ -134,7 +150,7 @@ unsafe extern "C" fn trampoline_new_sample(
     let callbacks = &*(callbacks as *const AppSinkCallbacks);
 
     let ret = if let Some(ref new_sample) = callbacks.new_sample {
-        (&mut *new_sample.borrow_mut())(&from_glib_borrow(appsink))
+        (&mut *new_sample.borrow_mut())(&from_glib_borrow(appsink)).into()
     } else {
         gst::FlowReturn::Error
     };
@@ -157,4 +173,72 @@ impl AppSink {
             );
         }
     }
+
+    pub fn connect_new_sample<
+        F: Fn(&AppSink) -> Result<gst::FlowSuccess, gst::FlowError> + Send + Sync + 'static,
+    >(
+        &self,
+        f: F,
+    ) -> SignalHandlerId {
+        unsafe {
+            let f: Box_<
+                Box_<
+                    Fn(&AppSink) -> Result<gst::FlowSuccess, gst::FlowError>
+                        + Send
+                        + Sync
+                        + 'static,
+                >,
+            > = Box_::new(Box_::new(f));
+            connect_raw(
+                self.to_glib_none().0,
+                b"new-sample\0".as_ptr() as *const _,
+                transmute(new_sample_trampoline as usize),
+                Box_::into_raw(f) as *mut _,
+            )
+        }
+    }
+
+    pub fn connect_new_preroll<
+        F: Fn(&AppSink) -> Result<gst::FlowSuccess, gst::FlowError> + Send + Sync + 'static,
+    >(
+        &self,
+        f: F,
+    ) -> SignalHandlerId {
+        unsafe {
+            let f: Box_<
+                Box_<
+                    Fn(&AppSink) -> Result<gst::FlowSuccess, gst::FlowError>
+                        + Send
+                        + Sync
+                        + 'static,
+                >,
+            > = Box_::new(Box_::new(f));
+            connect_raw(
+                self.to_glib_none().0,
+                b"new-preroll\0".as_ptr() as *const _,
+                transmute(new_preroll_trampoline as usize),
+                Box_::into_raw(f) as *mut _,
+            )
+        }
+    }
+}
+
+unsafe extern "C" fn new_sample_trampoline(
+    this: *mut ffi::GstAppSink,
+    f: glib_ffi::gpointer,
+) -> gst_ffi::GstFlowReturn {
+    let f: &&(Fn(&AppSink) -> Result<gst::FlowSuccess, gst::FlowError> + Send + Sync + 'static) =
+        transmute(f);
+    let ret: gst::FlowReturn = f(&from_glib_borrow(this)).into();
+    ret.to_glib()
+}
+
+unsafe extern "C" fn new_preroll_trampoline(
+    this: *mut ffi::GstAppSink,
+    f: glib_ffi::gpointer,
+) -> gst_ffi::GstFlowReturn {
+    let f: &&(Fn(&AppSink) -> Result<gst::FlowSuccess, gst::FlowError> + Send + Sync + 'static) =
+        transmute(f);
+    let ret: gst::FlowReturn = f(&from_glib_borrow(this)).into();
+    ret.to_glib()
 }

gstreamer-app/src/app_src.rs

@@ -147,23 +147,44 @@ unsafe extern "C" fn destroy_callbacks(ptr: gpointer) {
 }
 
 impl AppSrc {
-    pub fn push_buffer(&self, buffer: gst::Buffer) -> gst::FlowReturn {
-        unsafe {
+    pub fn end_of_stream(&self) -> Result<gst::FlowSuccess, gst::FlowError> {
+        let ret: gst::FlowReturn =
+            unsafe { from_glib(ffi::gst_app_src_end_of_stream(self.to_glib_none().0)) };
+        ret.into_result()
+    }
+
+    pub fn push_buffer(&self, buffer: gst::Buffer) -> Result<gst::FlowSuccess, gst::FlowError> {
+        let ret: gst::FlowReturn = unsafe {
             from_glib(ffi::gst_app_src_push_buffer(
                 self.to_glib_none().0,
                 buffer.into_ptr(),
             ))
-        }
+        };
+        ret.into_result()
     }
 
     #[cfg(any(feature = "v1_14", feature = "dox"))]
-    pub fn push_buffer_list(&self, list: gst::BufferList) -> gst::FlowReturn {
-        unsafe {
+    pub fn push_buffer_list(
+        &self,
+        list: gst::BufferList,
+    ) -> Result<gst::FlowSuccess, gst::FlowError> {
+        let ret: gst::FlowReturn = unsafe {
             from_glib(ffi::gst_app_src_push_buffer_list(
                 self.to_glib_none().0,
                 list.into_ptr(),
             ))
+        };
+        ret.into_result()
     }
+
+    pub fn push_sample(&self, sample: &gst::Sample) -> Result<gst::FlowSuccess, gst::FlowError> {
+        let ret: gst::FlowReturn = unsafe {
+            from_glib(ffi::gst_app_src_push_sample(
+                self.to_glib_none().0,
+                sample.to_glib_none().0,
+            ))
+        };
+        ret.into_result()
     }
 
     pub fn set_callbacks(&self, callbacks: AppSrcCallbacks) {

gstreamer-app/src/auto/app_sink.rs

@@ -173,22 +173,6 @@ impl AppSink {
         }
     }
 
-    pub fn connect_new_preroll<F: Fn(&AppSink) -> gst::FlowReturn + Send + Sync + 'static>(&self, f: F) -> SignalHandlerId {
-        unsafe {
-            let f: Box_<Box_<Fn(&AppSink) -> gst::FlowReturn + Send + Sync + 'static>> = Box_::new(Box_::new(f));
-            connect_raw(self.to_glib_none().0, b"new-preroll\0".as_ptr() as *const _,
-                transmute(new_preroll_trampoline as usize), Box_::into_raw(f) as *mut _)
-        }
-    }
-
-    pub fn connect_new_sample<F: Fn(&AppSink) -> gst::FlowReturn + Send + Sync + 'static>(&self, f: F) -> SignalHandlerId {
-        unsafe {
-            let f: Box_<Box_<Fn(&AppSink) -> gst::FlowReturn + Send + Sync + 'static>> = Box_::new(Box_::new(f));
-            connect_raw(self.to_glib_none().0, b"new-sample\0".as_ptr() as *const _,
-                transmute(new_sample_trampoline as usize), Box_::into_raw(f) as *mut _)
-        }
-    }
-
     pub fn connect_property_buffer_list_notify<F: Fn(&AppSink) + Send + Sync + 'static>(&self, f: F) -> SignalHandlerId {
         unsafe {
             let f: Box_<Box_<Fn(&AppSink) + Send + Sync + 'static>> = Box_::new(Box_::new(f));
@@ -254,16 +238,6 @@ unsafe extern "C" fn eos_trampoline(this: *mut ffi::GstAppSink, f: glib_ffi::gpo
     f(&from_glib_borrow(this))
 }
 
-unsafe extern "C" fn new_preroll_trampoline(this: *mut ffi::GstAppSink, f: glib_ffi::gpointer) -> gst_ffi::GstFlowReturn {
-    let f: &&(Fn(&AppSink) -> gst::FlowReturn + Send + Sync + 'static) = transmute(f);
-    f(&from_glib_borrow(this)).to_glib()
-}
-
-unsafe extern "C" fn new_sample_trampoline(this: *mut ffi::GstAppSink, f: glib_ffi::gpointer) -> gst_ffi::GstFlowReturn {
-    let f: &&(Fn(&AppSink) -> gst::FlowReturn + Send + Sync + 'static) = transmute(f);
-    f(&from_glib_borrow(this)).to_glib()
-}
-
 unsafe extern "C" fn notify_buffer_list_trampoline(this: *mut ffi::GstAppSink, _param_spec: glib_ffi::gpointer, f: glib_ffi::gpointer) {
     let f: &&(Fn(&AppSink) + Send + Sync + 'static) = transmute(f);
     f(&from_glib_borrow(this))

gstreamer-app/src/auto/app_src.rs

@@ -33,12 +33,6 @@ glib_wrapper! {
 }
 
 impl AppSrc {
-    pub fn end_of_stream(&self) -> gst::FlowReturn {
-        unsafe {
-            from_glib(ffi::gst_app_src_end_of_stream(self.to_glib_none().0))
-        }
-    }
-
     pub fn get_caps(&self) -> Option<gst::Caps> {
         unsafe {
             from_glib_full(ffi::gst_app_src_get_caps(self.to_glib_none().0))
@@ -82,12 +76,6 @@ impl AppSrc {
         }
     }
 
-    pub fn push_sample(&self, sample: &gst::Sample) -> gst::FlowReturn {
-        unsafe {
-            from_glib(ffi::gst_app_src_push_sample(self.to_glib_none().0, sample.to_glib_none().0))
-        }
-    }
-
     //pub fn set_callbacks(&self, callbacks: /*Ignored*/&mut AppSrcCallbacks, notify: /*Unknown conversion*//*Unimplemented*/DestroyNotify) {
     //    unsafe { TODO: call ffi::gst_app_src_set_callbacks() }
     //}

gstreamer-base/src/aggregator.rs

@@ -15,17 +15,18 @@ use Aggregator;
 use std::ops;
 
 pub trait AggregatorExtManual: 'static {
-    fn finish_buffer(&self, buffer: gst::Buffer) -> gst::FlowReturn;
+    fn finish_buffer(&self, buffer: gst::Buffer) -> Result<gst::FlowSuccess, gst::FlowError>;
 }
 
 impl<O: IsA<Aggregator>> AggregatorExtManual for O {
-    fn finish_buffer(&self, buffer: gst::Buffer) -> gst::FlowReturn {
-        unsafe {
+    fn finish_buffer(&self, buffer: gst::Buffer) -> Result<gst::FlowSuccess, gst::FlowError> {
+        let ret: gst::FlowReturn = unsafe {
             from_glib(ffi::gst_aggregator_finish_buffer(
                 self.to_glib_none().0,
                 buffer.into_ptr(),
             ))
-        }
+        };
+        ret.into_result()
     }
 }
 

gstreamer-base/src/auto/base_sink.rs

@@ -88,12 +88,8 @@ pub trait BaseSinkExt: 'static {
 
     fn set_ts_offset(&self, offset: gst::ClockTimeDiff);
 
-    fn wait(&self, time: gst::ClockTime) -> (gst::FlowReturn, gst::ClockTimeDiff);
-
     fn wait_clock(&self, time: gst::ClockTime) -> (gst::ClockReturn, gst::ClockTimeDiff);
 
-    fn wait_preroll(&self) -> gst::FlowReturn;
-
     fn get_property_async(&self) -> bool;
 
     fn set_property_async(&self, async: bool);
@@ -291,14 +287,6 @@ impl<O: IsA<BaseSink>> BaseSinkExt for O {
         }
     }
 
-    fn wait(&self, time: gst::ClockTime) -> (gst::FlowReturn, gst::ClockTimeDiff) {
-        unsafe {
-            let mut jitter = mem::uninitialized();
-            let ret = from_glib(ffi::gst_base_sink_wait(self.to_glib_none().0, time.to_glib(), &mut jitter));
-            (ret, jitter)
-        }
-    }
-
     fn wait_clock(&self, time: gst::ClockTime) -> (gst::ClockReturn, gst::ClockTimeDiff) {
         unsafe {
             let mut jitter = mem::uninitialized();
@@ -307,12 +295,6 @@ impl<O: IsA<BaseSink>> BaseSinkExt for O {
         }
     }
 
-    fn wait_preroll(&self) -> gst::FlowReturn {
-        unsafe {
-            from_glib(ffi::gst_base_sink_wait_preroll(self.to_glib_none().0))
-        }
-    }
-
     fn get_property_async(&self) -> bool {
         unsafe {
             let mut value = Value::from_type(<bool as StaticType>::static_type());

gstreamer-base/src/auto/base_src.rs

@@ -66,12 +66,6 @@ pub trait BaseSrcExt: 'static {
 
     fn set_live(&self, live: bool);
 
-    fn start_complete(&self, ret: gst::FlowReturn);
-
-    fn start_wait(&self) -> gst::FlowReturn;
-
-    fn wait_playing(&self) -> gst::FlowReturn;
-
     fn get_property_num_buffers(&self) -> i32;
 
     fn set_property_num_buffers(&self, num_buffers: i32);
@@ -188,24 +182,6 @@ impl<O: IsA<BaseSrc>> BaseSrcExt for O {
         }
     }
 
-    fn start_complete(&self, ret: gst::FlowReturn) {
-        unsafe {
-            ffi::gst_base_src_start_complete(self.to_glib_none().0, ret.to_glib());
-        }
-    }
-
-    fn start_wait(&self) -> gst::FlowReturn {
-        unsafe {
-            from_glib(ffi::gst_base_src_start_wait(self.to_glib_none().0))
-        }
-    }
-
-    fn wait_playing(&self) -> gst::FlowReturn {
-        unsafe {
-            from_glib(ffi::gst_base_src_wait_playing(self.to_glib_none().0))
-        }
-    }
-
     fn get_property_num_buffers(&self) -> i32 {
         unsafe {
             let mut value = Value::from_type(<i32 as StaticType>::static_type());

gstreamer-base/src/base_sink.rs

@@ -10,11 +10,19 @@ use ffi;
 use glib::translate::*;
 use glib::{IsA, IsClassFor};
 use gst;
+use std::mem;
 use std::ops;
 use BaseSink;
 
 pub trait BaseSinkExtManual: 'static {
     fn get_segment(&self) -> gst::Segment;
+
+    fn wait(
+        &self,
+        time: gst::ClockTime,
+    ) -> (Result<gst::FlowSuccess, gst::FlowError>, gst::ClockTimeDiff);
+
+    fn wait_preroll(&self) -> Result<gst::FlowSuccess, gst::FlowError>;
 }
 
 impl<O: IsA<BaseSink>> BaseSinkExtManual for O {
@@ -26,6 +34,27 @@ impl<O: IsA<BaseSink>> BaseSinkExtManual for O {
             from_glib_none(&sink.segment as *const _)
         }
     }
+
+    fn wait(
+        &self,
+        time: gst::ClockTime,
+    ) -> (Result<gst::FlowSuccess, gst::FlowError>, gst::ClockTimeDiff) {
+        unsafe {
+            let mut jitter = mem::uninitialized();
+            let ret: gst::FlowReturn = from_glib(ffi::gst_base_sink_wait(
+                self.to_glib_none().0,
+                time.to_glib(),
+                &mut jitter,
+            ));
+            (ret.into_result(), jitter)
+        }
+    }
+
+    fn wait_preroll(&self) -> Result<gst::FlowSuccess, gst::FlowError> {
+        let ret: gst::FlowReturn =
+            unsafe { from_glib(ffi::gst_base_sink_wait_preroll(self.to_glib_none().0)) };
+        ret.into_result()
+    }
 }
 
 #[repr(C)]

gstreamer-base/src/base_src.rs

@@ -15,6 +15,12 @@ use BaseSrc;
 
 pub trait BaseSrcExtManual: 'static {
     fn get_segment(&self) -> gst::Segment;
+
+    fn start_complete(&self, ret: Result<gst::FlowSuccess, gst::FlowError>);
+
+    fn start_wait(&self) -> Result<gst::FlowSuccess, gst::FlowError>;
+
+    fn wait_playing(&self) -> Result<gst::FlowSuccess, gst::FlowError>;
 }
 
 impl<O: IsA<BaseSrc>> BaseSrcExtManual for O {
@@ -26,6 +32,25 @@ impl<O: IsA<BaseSrc>> BaseSrcExtManual for O {
             from_glib_none(&src.segment as *const _)
         }
     }
+
+    fn start_complete(&self, ret: Result<gst::FlowSuccess, gst::FlowError>) {
+        let ret: gst::FlowReturn = ret.into();
+        unsafe {
+            ffi::gst_base_src_start_complete(self.to_glib_none().0, ret.to_glib());
+        }
+    }
+
+    fn start_wait(&self) -> Result<gst::FlowSuccess, gst::FlowError> {
+        let ret: gst::FlowReturn =
+            unsafe { from_glib(ffi::gst_base_src_start_wait(self.to_glib_none().0)) };
+        ret.into_result()
+    }
+
+    fn wait_playing(&self) -> Result<gst::FlowSuccess, gst::FlowError> {
+        let ret: gst::FlowReturn =
+            unsafe { from_glib(ffi::gst_base_src_wait_playing(self.to_glib_none().0)) };
+        ret.into_result()
+    }
 }
 
 #[repr(C)]

gstreamer-base/src/flow_combiner.rs

@@ -57,27 +57,34 @@ impl FlowCombiner {
         }
     }
 
-    pub fn update_flow(&self, fret: gst::FlowReturn) -> gst::FlowReturn {
-        unsafe {
+    pub fn update_flow<FRet: Into<gst::FlowReturn>>(
+        &self,
+        fret: FRet,
+    ) -> Result<gst::FlowSuccess, gst::FlowError> {
+        let fret: gst::FlowReturn = fret.into();
+        let ret: gst::FlowReturn = unsafe {
             from_glib(ffi::gst_flow_combiner_update_flow(
                 self.to_glib_none().0,
                 fret.to_glib(),
             ))
-        }
+        };
+        ret.into_result()
     }
 
-    pub fn update_pad_flow<P: IsA<gst::Pad>>(
+    pub fn update_pad_flow<P: IsA<gst::Pad>, FRet: Into<gst::FlowReturn>>(
         &self,
         pad: &P,
-        fret: gst::FlowReturn,
-    ) -> gst::FlowReturn {
-        unsafe {
+        fret: FRet,
+    ) -> Result<gst::FlowSuccess, gst::FlowError> {
+        let fret: gst::FlowReturn = fret.into();
+        let ret: gst::FlowReturn = unsafe {
             from_glib(ffi::gst_flow_combiner_update_pad_flow(
                 self.to_glib_none().0,
                 pad.to_glib_none().0,
                 fret.to_glib(),
             ))
-        }
+        };
+        ret.into_result()
     }
 }
 
@@ -114,15 +121,18 @@ impl UniqueFlowCombiner {
         self.0.reset();
     }
 
-    pub fn update_flow(&mut self, fret: gst::FlowReturn) -> gst::FlowReturn {
+    pub fn update_flow(
+        &mut self,
+        fret: Result<gst::FlowSuccess, gst::FlowError>,
+    ) -> Result<gst::FlowSuccess, gst::FlowError> {
         self.0.update_flow(fret)
     }
 
     pub fn update_pad_flow<P: IsA<gst::Pad>>(
         &mut self,
         pad: &P,
-        fret: gst::FlowReturn,
-    ) -> gst::FlowReturn {
+        fret: Result<gst::FlowSuccess, gst::FlowError>,
+    ) -> Result<gst::FlowSuccess, gst::FlowError> {
         self.0.update_pad_flow(pad, fret)
     }
 }

gstreamer-base/src/subclass/aggregator.rs

@@ -26,7 +26,7 @@ use AggregatorClass;
 use AggregatorPad;
 
 pub trait AggregatorImpl: ElementImpl + Send + Sync + 'static {
-    fn flush(&self, aggregator: &Aggregator) -> gst::FlowReturn {
+    fn flush(&self, aggregator: &Aggregator) -> Result<gst::FlowSuccess, gst::FlowError> {
         self.parent_flush(aggregator)
     }
 
@@ -39,7 +39,11 @@ pub trait AggregatorImpl: ElementImpl + Send + Sync + 'static {
         self.parent_clip(aggregator, aggregator_pad, buffer)
     }
 
-    fn finish_buffer(&self, aggregator: &Aggregator, buffer: gst::Buffer) -> gst::FlowReturn {
+    fn finish_buffer(
+        &self,
+        aggregator: &Aggregator,
+        buffer: gst::Buffer,
+    ) -> Result<gst::FlowSuccess, gst::FlowError> {
         self.parent_finish_buffer(aggregator, buffer)
     }
 
@@ -73,7 +77,11 @@ pub trait AggregatorImpl: ElementImpl + Send + Sync + 'static {
         self.parent_src_activate(aggregator, mode, active)
     }
 
-    fn aggregate(&self, aggregator: &Aggregator, timeout: bool) -> gst::FlowReturn;
+    fn aggregate(
+        &self,
+        aggregator: &Aggregator,
+        timeout: bool,
+    ) -> Result<gst::FlowSuccess, gst::FlowError>;
 
     fn start(&self, aggregator: &Aggregator) -> bool {
         self.parent_start(aggregator)
@@ -113,7 +121,7 @@ pub trait AggregatorImpl: ElementImpl + Send + Sync + 'static {
         self.parent_negotiated_src_caps(aggregator, caps)
     }
 
-    fn parent_flush(&self, aggregator: &Aggregator) -> gst::FlowReturn {
+    fn parent_flush(&self, aggregator: &Aggregator) -> Result<gst::FlowSuccess, gst::FlowError> {
         unsafe {
             let data = self.get_type_data();
             let parent_class = data.as_ref().get_parent_class() as *mut ffi::GstAggregatorClass;
@@ -121,6 +129,7 @@ pub trait AggregatorImpl: ElementImpl + Send + Sync + 'static {
                 .flush
                 .map(|f| from_glib(f(aggregator.to_glib_none().0)))
                 .unwrap_or(gst::FlowReturn::Ok)
+                .into_result()
         }
     }
 
@@ -148,7 +157,7 @@ pub trait AggregatorImpl: ElementImpl + Send + Sync + 'static {
         &self,
         aggregator: &Aggregator,
         buffer: gst::Buffer,
-    ) -> gst::FlowReturn {
+    ) -> Result<gst::FlowSuccess, gst::FlowError> {
         unsafe {
             let data = self.get_type_data();
             let parent_class = data.as_ref().get_parent_class() as *mut ffi::GstAggregatorClass;
@@ -156,6 +165,7 @@ pub trait AggregatorImpl: ElementImpl + Send + Sync + 'static {
                 .finish_buffer
                 .map(|f| from_glib(f(aggregator.to_glib_none().0, buffer.into_ptr())))
                 .unwrap_or(gst::FlowReturn::Ok)
+                .into_result()
         }
     }
 
@@ -247,7 +257,11 @@ pub trait AggregatorImpl: ElementImpl + Send + Sync + 'static {
         }
     }
 
-    fn parent_aggregate(&self, aggregator: &Aggregator, timeout: bool) -> gst::FlowReturn {
+    fn parent_aggregate(
+        &self,
+        aggregator: &Aggregator,
+        timeout: bool,
+    ) -> Result<gst::FlowSuccess, gst::FlowError> {
         unsafe {
             let data = self.get_type_data();
             let parent_class = data.as_ref().get_parent_class() as *mut ffi::GstAggregatorClass;
@@ -255,6 +269,7 @@ pub trait AggregatorImpl: ElementImpl + Send + Sync + 'static {
                 .aggregate
                 .map(|f| from_glib(f(aggregator.to_glib_none().0, timeout.to_glib())))
                 .unwrap_or(gst::FlowReturn::Error)
+                .into_result()
         }
     }
 
@@ -403,7 +418,7 @@ where
     let wrap: Aggregator = from_glib_borrow(ptr);
 
     gst_panic_to_error!(&wrap, &instance.panicked(), gst::FlowReturn::Error, {
-        imp.flush(&wrap)
+        imp.flush(&wrap).into()
     })
     .to_glib()
 }
@@ -447,7 +462,7 @@ where
     let wrap: Aggregator = from_glib_borrow(ptr);
 
     gst_panic_to_error!(&wrap, &instance.panicked(), gst::FlowReturn::Error, {
-        imp.finish_buffer(&wrap, from_glib_full(buffer))
+        imp.finish_buffer(&wrap, from_glib_full(buffer)).into()
     })
     .to_glib()
 }
@@ -572,7 +587,7 @@ where
     let wrap: Aggregator = from_glib_borrow(ptr);
 
     gst_panic_to_error!(&wrap, &instance.panicked(), gst::FlowReturn::Error, {
-        imp.aggregate(&wrap, from_glib(timeout))
+        imp.aggregate(&wrap, from_glib(timeout)).into()
     })
     .to_glib()
 }

gstreamer-base/src/subclass/aggregator_pad.rs

@@ -22,7 +22,11 @@ use AggregatorPad;
 use AggregatorPadClass;
 
 pub trait AggregatorPadImpl: PadImpl + Send + Sync + 'static {
-    fn flush(&self, aggregator_pad: &AggregatorPad, aggregator: &Aggregator) -> gst::FlowReturn {
+    fn flush(
+        &self,
+        aggregator_pad: &AggregatorPad,
+        aggregator: &Aggregator,
+    ) -> Result<gst::FlowSuccess, gst::FlowError> {
         self.parent_flush(aggregator_pad, aggregator)
     }
 
@@ -39,7 +43,7 @@ pub trait AggregatorPadImpl: PadImpl + Send + Sync + 'static {
         &self,
         aggregator_pad: &AggregatorPad,
         aggregator: &Aggregator,
-    ) -> gst::FlowReturn {
+    ) -> Result<gst::FlowSuccess, gst::FlowError> {
         unsafe {
             let data = self.get_type_data();
             let parent_class = data.as_ref().get_parent_class() as *mut ffi::GstAggregatorPadClass;
@@ -52,6 +56,7 @@ pub trait AggregatorPadImpl: PadImpl + Send + Sync + 'static {
                     ))
                 })
                 .unwrap_or(gst::FlowReturn::Ok)
+                .into_result()
         }
     }
 
@@ -101,7 +106,8 @@ where
     let imp = instance.get_impl();
     let wrap: AggregatorPad = from_glib_borrow(ptr);
 
-    imp.flush(&wrap, &from_glib_borrow(aggregator)).to_glib()
+    let res: gst::FlowReturn = imp.flush(&wrap, &from_glib_borrow(aggregator)).into();
+    res.to_glib()
 }
 
 unsafe extern "C" fn aggregator_pad_skip_buffer<T: ObjectSubclass>(

gstreamer-base/src/subclass/base_sink.rs

@@ -31,32 +31,40 @@ pub trait BaseSinkImpl: ElementImpl + Send + Sync + 'static {
         true
     }
 
-    fn render(&self, element: &BaseSink, buffer: &gst::BufferRef) -> gst::FlowReturn;
+    fn render(
+        &self,
+        element: &BaseSink,
+        buffer: &gst::BufferRef,
+    ) -> Result<gst::FlowSuccess, gst::FlowError>;
 
-    fn prepare(&self, _element: &BaseSink, _buffer: &gst::BufferRef) -> gst::FlowReturn {
-        gst::FlowReturn::Ok
+    fn prepare(
+        &self,
+        _element: &BaseSink,
+        _buffer: &gst::BufferRef,
+    ) -> Result<gst::FlowSuccess, gst::FlowError> {
+        Ok(gst::FlowSuccess::Ok)
     }
 
-    fn render_list(&self, element: &BaseSink, list: &gst::BufferListRef) -> gst::FlowReturn {
+    fn render_list(
+        &self,
+        element: &BaseSink,
+        list: &gst::BufferListRef,
+    ) -> Result<gst::FlowSuccess, gst::FlowError> {
         for buffer in list.iter() {
-            let ret = self.render(element, buffer);
-            if ret != gst::FlowReturn::Ok {
-                return ret;
+            self.render(element, buffer)?;
         }
+        Ok(gst::FlowSuccess::Ok)
     }
 
-        gst::FlowReturn::Ok
-    }
-
-    fn prepare_list(&self, element: &BaseSink, list: &gst::BufferListRef) -> gst::FlowReturn {
+    fn prepare_list(
+        &self,
+        element: &BaseSink,
+        list: &gst::BufferListRef,
+    ) -> Result<gst::FlowSuccess, gst::FlowError> {
         for buffer in list.iter() {
-            let ret = self.prepare(element, buffer);
-            if ret != gst::FlowReturn::Ok {
-                return ret;
+            self.prepare(element, buffer)?;
         }
-        }
-
-        gst::FlowReturn::Ok
+        Ok(gst::FlowSuccess::Ok)
     }
 
     fn query(&self, element: &BaseSink, query: &mut gst::QueryRef) -> bool {
@@ -224,7 +232,7 @@ where
     let buffer = gst::BufferRef::from_ptr(buffer);
 
     gst_panic_to_error!(&wrap, &instance.panicked(), gst::FlowReturn::Error, {
-        imp.render(&wrap, buffer)
+        imp.render(&wrap, buffer).into()
     })
     .to_glib()
 }
@@ -244,7 +252,7 @@ where
     let buffer = gst::BufferRef::from_ptr(buffer);
 
     gst_panic_to_error!(&wrap, &instance.panicked(), gst::FlowReturn::Error, {
-        imp.prepare(&wrap, buffer)
+        imp.prepare(&wrap, buffer).into()
     })
     .to_glib()
 }
@@ -264,7 +272,7 @@ where
     let list = gst::BufferListRef::from_ptr(list);
 
     gst_panic_to_error!(&wrap, &instance.panicked(), gst::FlowReturn::Error, {
-        imp.render_list(&wrap, list)
+        imp.render_list(&wrap, list).into()
     })
     .to_glib()
 }
@@ -284,7 +292,7 @@ where
     let list = gst::BufferListRef::from_ptr(list);
 
     gst_panic_to_error!(&wrap, &instance.panicked(), gst::FlowReturn::Error, {
-        imp.prepare_list(&wrap, list)
+        imp.prepare_list(&wrap, list).into()
     })
     .to_glib()
 }

gstreamer-base/src/subclass/base_src.rs

@@ -45,7 +45,7 @@ pub trait BaseSrcImpl: ElementImpl + Send + Sync + 'static {
         _offset: u64,
         _length: u32,
         _buffer: &mut gst::BufferRef,
-    ) -> gst::FlowReturn {
+    ) -> Result<gst::FlowSuccess, gst::FlowError> {
         unimplemented!()
     }
 
@@ -325,7 +325,7 @@ where
     let buffer = gst::BufferRef::from_mut_ptr(buffer);
 
     gst_panic_to_error!(&wrap, &instance.panicked(), gst::FlowReturn::Error, {
-        imp.fill(&wrap, offset, length, buffer)
+        imp.fill(&wrap, offset, length, buffer).into()
     })
     .to_glib()
 }

gstreamer-base/src/subclass/base_transform.rs

@@ -104,11 +104,15 @@ pub trait BaseTransformImpl: ElementImpl + Send + Sync + 'static {
         _element: &BaseTransform,
         _inbuf: &gst::Buffer,
         _outbuf: &mut gst::BufferRef,
-    ) -> gst::FlowReturn {
+    ) -> Result<gst::FlowSuccess, gst::FlowError> {
         unimplemented!();
     }
 
-    fn transform_ip(&self, _element: &BaseTransform, _buf: &mut gst::BufferRef) -> gst::FlowReturn {
+    fn transform_ip(
+        &self,
+        _element: &BaseTransform,
+        _buf: &mut gst::BufferRef,
+    ) -> Result<gst::FlowSuccess, gst::FlowError> {
         unimplemented!();
     }
 
@@ -116,7 +120,7 @@ pub trait BaseTransformImpl: ElementImpl + Send + Sync + 'static {
         &self,
         _element: &BaseTransform,
         _buf: &gst::BufferRef,
-    ) -> gst::FlowReturn {
+    ) -> Result<gst::FlowSuccess, gst::FlowError> {
         unimplemented!();
     }
 
@@ -605,6 +609,7 @@ where
             &from_glib_borrow(inbuf),
             gst::BufferRef::from_mut_ptr(outbuf),
         )
+        .into()
     })
     .to_glib()
 }
@@ -628,8 +633,10 @@ where
     gst_panic_to_error!(&wrap, &instance.panicked(), gst::FlowReturn::Error, {
         if from_glib(ffi::gst_base_transform_is_passthrough(ptr)) {
             imp.transform_ip_passthrough(&wrap, gst::BufferRef::from_ptr(buf))
+                .into()
         } else {
             imp.transform_ip(&wrap, gst::BufferRef::from_mut_ptr(buf))
+                .into()
         }
     })
     .to_glib()

gstreamer-check/src/harness.rs

@@ -267,8 +267,10 @@ impl Harness {
         unsafe { from_glib_full(ffi::gst_harness_pull_upstream_event(self.0.as_ptr())) }
     }
 
-    pub fn push(&mut self, buffer: gst::Buffer) -> gst::FlowReturn {
-        unsafe { from_glib(ffi::gst_harness_push(self.0.as_ptr(), buffer.into_ptr())) }
+    pub fn push(&mut self, buffer: gst::Buffer) -> Result<gst::FlowSuccess, gst::FlowError> {
+        let ret: gst::FlowReturn =
+            unsafe { from_glib(ffi::gst_harness_push(self.0.as_ptr(), buffer.into_ptr())) };
+        ret.into_result()
     }
 
     pub fn push_and_pull(&mut self, buffer: gst::Buffer) -> Option<gst::Buffer> {
@@ -289,12 +291,16 @@ impl Harness {
         }
     }
 
-    pub fn push_from_src(&mut self) -> gst::FlowReturn {
-        unsafe { from_glib(ffi::gst_harness_push_from_src(self.0.as_ptr())) }
+    pub fn push_from_src(&mut self) -> Result<gst::FlowSuccess, gst::FlowError> {
+        let ret: gst::FlowReturn =
+            unsafe { from_glib(ffi::gst_harness_push_from_src(self.0.as_ptr())) };
+        ret.into_result()
     }
 
-    pub fn push_to_sink(&mut self) -> gst::FlowReturn {
-        unsafe { from_glib(ffi::gst_harness_push_to_sink(self.0.as_ptr())) }
+    pub fn push_to_sink(&mut self) -> Result<gst::FlowSuccess, gst::FlowError> {
+        let ret: gst::FlowReturn =
+            unsafe { from_glib(ffi::gst_harness_push_to_sink(self.0.as_ptr())) };
+        ret.into_result()
     }
 
     pub fn push_upstream_event(&mut self, event: gst::Event) -> bool {
@@ -391,23 +397,29 @@ impl Harness {
         }
     }
 
-    pub fn sink_push_many(&mut self, pushes: u32) -> gst::FlowReturn {
-        unsafe {
+    pub fn sink_push_many(&mut self, pushes: u32) -> Result<gst::FlowSuccess, gst::FlowError> {
+        let ret: gst::FlowReturn = unsafe {
             from_glib(ffi::gst_harness_sink_push_many(
                 self.0.as_ptr(),
                 pushes as i32,
             ))
-        }
+        };
+        ret.into_result()
     }
 
-    pub fn src_crank_and_push_many(&mut self, cranks: u32, pushes: u32) -> gst::FlowReturn {
-        unsafe {
+    pub fn src_crank_and_push_many(
+        &mut self,
+        cranks: u32,
+        pushes: u32,
+    ) -> Result<gst::FlowSuccess, gst::FlowError> {
+        let ret: gst::FlowReturn = unsafe {
             from_glib(ffi::gst_harness_src_crank_and_push_many(
                 self.0.as_ptr(),
                 cranks as i32,
                 pushes as i32,
             ))
-        }
+        };
+        ret.into_result()
     }
 
     pub fn src_push_event(&mut self) -> bool {

gstreamer-rtsp-server/src/auto/rtsp_stream.rs

@@ -124,10 +124,6 @@ pub trait RTSPStreamExt: 'static {
 
     fn leave_bin<P: IsA<gst::Bin>, Q: IsA<gst::Element>>(&self, bin: &P, rtpbin: &Q) -> Result<(), glib::error::BoolError>;
 
-    fn recv_rtcp(&self, buffer: &gst::Buffer) -> gst::FlowReturn;
-
-    fn recv_rtp(&self, buffer: &gst::Buffer) -> gst::FlowReturn;
-
     fn remove_transport(&self, trans: &RTSPStreamTransport) -> Result<(), glib::error::BoolError>;
 
     fn request_aux_sender(&self, sessid: u32) -> Option<gst::Element>;
@@ -425,18 +421,6 @@ impl<O: IsA<RTSPStream>> RTSPStreamExt for O {
         }
     }
 
-    fn recv_rtcp(&self, buffer: &gst::Buffer) -> gst::FlowReturn {
-        unsafe {
-            from_glib(ffi::gst_rtsp_stream_recv_rtcp(self.to_glib_none().0, buffer.to_glib_full()))
-        }
-    }
-
-    fn recv_rtp(&self, buffer: &gst::Buffer) -> gst::FlowReturn {
-        unsafe {
-            from_glib(ffi::gst_rtsp_stream_recv_rtp(self.to_glib_none().0, buffer.to_glib_full()))
-        }
-    }
-
     fn remove_transport(&self, trans: &RTSPStreamTransport) -> Result<(), glib::error::BoolError> {
         unsafe {
             glib_result_from_gboolean!(ffi::gst_rtsp_stream_remove_transport(self.to_glib_none().0, trans.to_glib_none().0), "Failed to remove transport")

gstreamer-rtsp-server/src/auto/rtsp_stream_transport.rs

@@ -38,8 +38,6 @@ pub trait RTSPStreamTransportExt: 'static {
 
     fn keep_alive(&self);
 
-    fn recv_data(&self, channel: u32, buffer: &gst::Buffer) -> gst::FlowReturn;
-
     fn send_rtcp(&self, buffer: &gst::Buffer) -> Result<(), glib::error::BoolError>;
 
     fn send_rtp(&self, buffer: &gst::Buffer) -> Result<(), glib::error::BoolError>;
@@ -92,12 +90,6 @@ impl<O: IsA<RTSPStreamTransport>> RTSPStreamTransportExt for O {
         }
     }
 
-    fn recv_data(&self, channel: u32, buffer: &gst::Buffer) -> gst::FlowReturn {
-        unsafe {
-            from_glib(ffi::gst_rtsp_stream_transport_recv_data(self.to_glib_none().0, channel, buffer.to_glib_full()))
-        }
-    }
-
     fn send_rtcp(&self, buffer: &gst::Buffer) -> Result<(), glib::error::BoolError> {
         unsafe {
             glib_result_from_gboolean!(ffi::gst_rtsp_stream_transport_send_rtcp(self.to_glib_none().0, buffer.to_glib_none().0), "Failed to send rtcp")

gstreamer-rtsp-server/src/lib.rs

@@ -57,6 +57,8 @@ mod rtsp_context;
 mod rtsp_media_factory;
 mod rtsp_server;
 mod rtsp_session_pool;
+mod rtsp_stream;
+mod rtsp_stream_transport;
 mod rtsp_token;
 
 pub use rtsp_address_pool::RTSPAddressPoolExtManual;
@@ -141,4 +143,6 @@ pub mod prelude {
     pub use rtsp_media_factory::RTSPMediaFactoryExtManual;
     pub use rtsp_server::RTSPServerExtManual;
     pub use rtsp_session_pool::RTSPSessionPoolExtManual;
+    pub use rtsp_stream::RTSPStreamExtManual;
+    pub use rtsp_stream_transport::RTSPStreamTransportExtManual;
 }

gstreamer-rtsp-server/src/rtsp_stream.rs

@@ -0,0 +1,33 @@
+use ffi;
+use glib::object::IsA;
+use glib::translate::*;
+use gst;
+use RTSPStream;
+
+pub trait RTSPStreamExtManual: 'static {
+    fn recv_rtcp(&self, buffer: &gst::Buffer) -> Result<gst::FlowSuccess, gst::FlowError>;
+
+    fn recv_rtp(&self, buffer: &gst::Buffer) -> Result<gst::FlowSuccess, gst::FlowError>;
+}
+
+impl<O: IsA<RTSPStream>> RTSPStreamExtManual for O {
+    fn recv_rtcp(&self, buffer: &gst::Buffer) -> Result<gst::FlowSuccess, gst::FlowError> {
+        let ret: gst::FlowReturn = unsafe {
+            from_glib(ffi::gst_rtsp_stream_recv_rtcp(
+                self.to_glib_none().0,
+                buffer.to_glib_full(),
+            ))
+        };
+        ret.into_result()
+    }
+
+    fn recv_rtp(&self, buffer: &gst::Buffer) -> Result<gst::FlowSuccess, gst::FlowError> {
+        let ret: gst::FlowReturn = unsafe {
+            from_glib(ffi::gst_rtsp_stream_recv_rtp(
+                self.to_glib_none().0,
+                buffer.to_glib_full(),
+            ))
+        };
+        ret.into_result()
+    }
+}

gstreamer-rtsp-server/src/rtsp_stream_transport.rs

@@ -0,0 +1,30 @@
+use ffi;
+use glib::object::IsA;
+use glib::translate::*;
+use gst;
+use RTSPStreamTransport;
+
+pub trait RTSPStreamTransportExtManual: 'static {
+    fn recv_data(
+        &self,
+        channel: u32,
+        buffer: &gst::Buffer,
+    ) -> Result<gst::FlowSuccess, gst::FlowError>;
+}
+
+impl<O: IsA<RTSPStreamTransport>> RTSPStreamTransportExtManual for O {
+    fn recv_data(
+        &self,
+        channel: u32,
+        buffer: &gst::Buffer,
+    ) -> Result<gst::FlowSuccess, gst::FlowError> {
+        let ret: gst::FlowReturn = unsafe {
+            from_glib(ffi::gst_rtsp_stream_transport_recv_data(
+                self.to_glib_none().0,
+                channel,
+                buffer.to_glib_full(),
+            ))
+        };
+        ret.into_result()
+    }
+}

gstreamer/src/auto/element.rs

@@ -16,9 +16,6 @@ use Pad;
 use PadLinkCheck;
 use PadTemplate;
 use Plugin;
-use State;
-use StateChange;
-use StateChangeReturn;
 use URIType;
 use ffi;
 use glib;
@@ -29,7 +26,6 @@ use glib::signal::connect_raw;
 use glib::translate::*;
 use glib_ffi;
 use std::boxed::Box as Box_;
-use std::mem;
 use std::mem::transmute;
 use std::ptr;
 
@@ -74,10 +70,6 @@ pub trait ElementExt: 'static {
     //#[cfg(any(feature = "v1_10", feature = "dox"))]
     //fn call_async(&self, func: /*Unknown conversion*//*Unimplemented*/ElementCallAsyncFunc, destroy_notify: /*Unknown conversion*//*Unimplemented*/DestroyNotify);
 
-    fn change_state(&self, transition: StateChange) -> StateChangeReturn;
-
-    fn continue_state(&self, ret: StateChangeReturn) -> StateChangeReturn;
-
     fn create_all_pads(&self);
 
     //#[cfg(any(feature = "v1_14", feature = "dox"))]
@@ -109,8 +101,6 @@ pub trait ElementExt: 'static {
 
     fn get_start_time(&self) -> ClockTime;
 
-    fn get_state(&self, timeout: ClockTime) -> (StateChangeReturn, State, State);
-
     fn get_static_pad(&self, name: &str) -> Option<Pad>;
 
     fn is_locked_state(&self) -> bool;
@@ -164,8 +154,6 @@ pub trait ElementExt: 'static {
 
     fn set_start_time(&self, time: ClockTime);
 
-    fn set_state(&self, state: State) -> StateChangeReturn;
-
     fn sync_state_with_parent(&self) -> Result<(), glib::error::BoolError>;
 
     fn unlink<P: IsA<Element>>(&self, dest: &P);
@@ -199,18 +187,6 @@ impl<O: IsA<Element>> ElementExt for O {
     //    unsafe { TODO: call ffi::gst_element_call_async() }
     //}
 
-    fn change_state(&self, transition: StateChange) -> StateChangeReturn {
-        unsafe {
-            from_glib(ffi::gst_element_change_state(self.to_glib_none().0, transition.to_glib()))
-        }
-    }
-
-    fn continue_state(&self, ret: StateChangeReturn) -> StateChangeReturn {
-        unsafe {
-            from_glib(ffi::gst_element_continue_state(self.to_glib_none().0, ret.to_glib()))
-        }
-    }
-
     fn create_all_pads(&self) {
         unsafe {
             ffi::gst_element_create_all_pads(self.to_glib_none().0);
@@ -294,15 +270,6 @@ impl<O: IsA<Element>> ElementExt for O {
         }
     }
 
-    fn get_state(&self, timeout: ClockTime) -> (StateChangeReturn, State, State) {
-        unsafe {
-            let mut state = mem::uninitialized();
-            let mut pending = mem::uninitialized();
-            let ret = from_glib(ffi::gst_element_get_state(self.to_glib_none().0, &mut state, &mut pending, timeout.to_glib()));
-            (ret, from_glib(state), from_glib(pending))
-        }
-    }
-
     fn get_static_pad(&self, name: &str) -> Option<Pad> {
         unsafe {
             from_glib_full(ffi::gst_element_get_static_pad(self.to_glib_none().0, name.to_glib_none().0))
@@ -472,12 +439,6 @@ impl<O: IsA<Element>> ElementExt for O {
         }
     }
 
-    fn set_state(&self, state: State) -> StateChangeReturn {
-        unsafe {
-            from_glib(ffi::gst_element_set_state(self.to_glib_none().0, state.to_glib()))
-        }
-    }
-
     fn sync_state_with_parent(&self) -> Result<(), glib::error::BoolError> {
         unsafe {
             glib_result_from_gboolean!(ffi::gst_element_sync_state_with_parent(self.to_glib_none().0), "Failed to sync state with parent")

gstreamer/src/auto/pad.rs

@@ -6,12 +6,11 @@ use Caps;
 use Element;
 use Event;
 use EventType;
-use FlowReturn;
 use Object;
 use PadClass;
 use PadDirection;
+#[cfg(any(feature = "v1_10", feature = "dox"))]
 use PadLinkCheck;
-use PadLinkReturn;
 use PadMode;
 use PadTemplate;
 #[cfg(any(feature = "v1_10", feature = "dox"))]
@@ -89,8 +88,6 @@ pub trait PadExt: 'static {
 
     //fn get_element_private(&self) -> /*Unimplemented*/Option<Fundamental: Pointer>;
 
-    fn get_last_flow_return(&self) -> FlowReturn;
-
     fn get_offset(&self) -> i64;
 
     fn get_pad_template(&self) -> Option<PadTemplate>;
@@ -125,10 +122,6 @@ pub trait PadExt: 'static {
 
     //fn iterate_internal_links_default<'a, P: IsA<Object> + 'a, Q: Into<Option<&'a P>>>(&self, parent: Q) -> /*Ignored*/Option<Iterator>;
 
-    fn link<P: IsA<Pad>>(&self, sinkpad: &P) -> PadLinkReturn;
-
-    fn link_full<P: IsA<Pad>>(&self, sinkpad: &P, flags: PadLinkCheck) -> PadLinkReturn;
-
     #[cfg(any(feature = "v1_10", feature = "dox"))]
     fn link_maybe_ghosting<P: IsA<Pad>>(&self, sink: &P) -> Result<(), glib::error::BoolError>;
 
@@ -183,8 +176,6 @@ pub trait PadExt: 'static {
 
     fn stop_task(&self) -> Result<(), glib::error::BoolError>;
 
-    fn store_sticky_event(&self, event: &Event) -> FlowReturn;
-
     fn unlink<P: IsA<Pad>>(&self, sinkpad: &P) -> Result<(), glib::error::BoolError>;
 
     fn use_fixed_caps(&self);
@@ -271,12 +262,6 @@ impl<O: IsA<Pad>> PadExt for O {
     //    unsafe { TODO: call ffi::gst_pad_get_element_private() }
     //}
 
-    fn get_last_flow_return(&self) -> FlowReturn {
-        unsafe {
-            from_glib(ffi::gst_pad_get_last_flow_return(self.to_glib_none().0))
-        }
-    }
-
     fn get_offset(&self) -> i64 {
         unsafe {
             ffi::gst_pad_get_offset(self.to_glib_none().0)
@@ -371,18 +356,6 @@ impl<O: IsA<Pad>> PadExt for O {
     //    unsafe { TODO: call ffi::gst_pad_iterate_internal_links_default() }
     //}
 
-    fn link<P: IsA<Pad>>(&self, sinkpad: &P) -> PadLinkReturn {
-        unsafe {
-            from_glib(ffi::gst_pad_link(self.to_glib_none().0, sinkpad.to_glib_none().0))
-        }
-    }
-
-    fn link_full<P: IsA<Pad>>(&self, sinkpad: &P, flags: PadLinkCheck) -> PadLinkReturn {
-        unsafe {
-            from_glib(ffi::gst_pad_link_full(self.to_glib_none().0, sinkpad.to_glib_none().0, flags.to_glib()))
-        }
-    }
-
     #[cfg(any(feature = "v1_10", feature = "dox"))]
     fn link_maybe_ghosting<P: IsA<Pad>>(&self, sink: &P) -> Result<(), glib::error::BoolError> {
         unsafe {
@@ -517,12 +490,6 @@ impl<O: IsA<Pad>> PadExt for O {
         }
     }
 
-    fn store_sticky_event(&self, event: &Event) -> FlowReturn {
-        unsafe {
-            from_glib(ffi::gst_pad_store_sticky_event(self.to_glib_none().0, event.to_glib_none().0))
-        }
-    }
-
     fn unlink<P: IsA<Pad>>(&self, sinkpad: &P) -> Result<(), glib::error::BoolError> {
         unsafe {
             glib_result_from_gboolean!(ffi::gst_pad_unlink(self.to_glib_none().0, sinkpad.to_glib_none().0), "Failed to unlink pad")

gstreamer/src/clock.rs

@@ -17,7 +17,9 @@ use std::mem;
 use std::mem::transmute;
 use std::ptr;
 use Clock;
+use ClockError;
 use ClockReturn;
+use ClockSuccess;
 use ClockTime;
 use ClockTimeDiff;
 
@@ -68,26 +70,28 @@ impl ClockId {
         unsafe { ffi::gst_clock_id_unschedule(self.to_glib_none().0) }
     }
 
-    pub fn wait(&self) -> (ClockReturn, ClockTimeDiff) {
+    pub fn wait(&self) -> (Result<ClockSuccess, ClockError>, ClockTimeDiff) {
         unsafe {
             let mut jitter = mem::uninitialized();
-            let res = ffi::gst_clock_id_wait(self.to_glib_none().0, &mut jitter);
-            (from_glib(res), jitter)
+            let res: ClockReturn =
+                from_glib(ffi::gst_clock_id_wait(self.to_glib_none().0, &mut jitter));
+            (res.into_result(), jitter)
         }
     }
 
-    pub fn wait_async<F>(&self, func: F) -> ClockReturn
+    pub fn wait_async<F>(&self, func: F) -> Result<ClockSuccess, ClockError>
     where
         F: Fn(&Clock, ClockTime, &ClockId) -> bool + Send + 'static,
     {
-        unsafe {
+        let ret: ClockReturn = unsafe {
             from_glib(ffi::gst_clock_id_wait_async(
                 self.to_glib_none().0,
                 Some(trampoline_wait_async),
                 into_raw_wait_async(func),
                 Some(destroy_closure_wait_async),
             ))
-        }
+        };
+        ret.into_result()
     }
 }
 
@@ -251,7 +255,7 @@ mod tests {
         let id = clock.new_single_shot_id(now + 20 * ::MSECOND).unwrap();
         let (res, _) = id.wait();
 
-        assert!(res == ClockReturn::Ok || res == ClockReturn::Early);
+        assert!(res == Ok(ClockSuccess::Ok) || res == Err(ClockError::Early));
     }
 
     #[test]
@@ -269,7 +273,7 @@ mod tests {
             true
         });
 
-        assert!(res == ClockReturn::Ok);
+        assert!(res == Ok(ClockSuccess::Ok));
 
         assert_eq!(receiver.recv(), Ok(()));
     }

gstreamer/src/element.rs

@@ -18,6 +18,7 @@ use glib::translate::{
 };
 use glib::{IsA, IsClassFor};
 use miniobject::MiniObject;
+use ClockTime;
 use Event;
 use Format;
 use FormattedValue;
@@ -26,6 +27,11 @@ use Pad;
 use PadTemplate;
 use QueryRef;
 use SpecificFormattedValue;
+use State;
+use StateChange;
+use StateChangeError;
+use StateChangeReturn;
+use StateChangeSuccess;
 
 use std::ffi::CStr;
 use std::mem;
@@ -95,6 +101,19 @@ impl FromGlib<libc::c_ulong> for NotifyWatchId {
 pub trait ElementExtManual: 'static {
     fn get_element_class(&self) -> &ElementClass;
 
+    fn change_state(&self, transition: StateChange)
+        -> Result<StateChangeSuccess, StateChangeError>;
+    fn continue_state(
+        &self,
+        ret: StateChangeReturn,
+    ) -> Result<StateChangeSuccess, StateChangeError>;
+
+    fn get_state(
+        &self,
+        timeout: ClockTime,
+    ) -> (Result<StateChangeSuccess, StateChangeError>, State, State);
+    fn set_state(&self, state: State) -> Result<StateChangeSuccess, StateChangeError>;
+
     fn query(&self, query: &mut QueryRef) -> bool;
 
     fn send_event(&self, event: Event) -> bool;
@@ -203,6 +222,59 @@ impl<O: IsA<Element>> ElementExtManual for O {
         }
     }
 
+    fn change_state(
+        &self,
+        transition: StateChange,
+    ) -> Result<StateChangeSuccess, StateChangeError> {
+        let ret: StateChangeReturn = unsafe {
+            from_glib(ffi::gst_element_change_state(
+                self.to_glib_none().0,
+                transition.to_glib(),
+            ))
+        };
+        ret.into_result()
+    }
+
+    fn continue_state(
+        &self,
+        ret: StateChangeReturn,
+    ) -> Result<StateChangeSuccess, StateChangeError> {
+        let ret: StateChangeReturn = unsafe {
+            from_glib(ffi::gst_element_continue_state(
+                self.to_glib_none().0,
+                ret.to_glib(),
+            ))
+        };
+        ret.into_result()
+    }
+
+    fn get_state(
+        &self,
+        timeout: ClockTime,
+    ) -> (Result<StateChangeSuccess, StateChangeError>, State, State) {
+        unsafe {
+            let mut state = mem::uninitialized();
+            let mut pending = mem::uninitialized();
+            let ret: StateChangeReturn = from_glib(ffi::gst_element_get_state(
+                self.to_glib_none().0,
+                &mut state,
+                &mut pending,
+                timeout.to_glib(),
+            ));
+            (ret.into_result(), from_glib(state), from_glib(pending))
+        }
+    }
+
+    fn set_state(&self, state: State) -> Result<StateChangeSuccess, StateChangeError> {
+        let ret: StateChangeReturn = unsafe {
+            from_glib(ffi::gst_element_set_state(
+                self.to_glib_none().0,
+                state.to_glib(),
+            ))
+        };
+        ret.into_result()
+    }
+
     fn query(&self, query: &mut QueryRef) -> bool {
         unsafe {
             from_glib(ffi::gst_element_query(

gstreamer/src/enums.rs

@@ -75,6 +75,15 @@ impl Error for StateChangeError {
     }
 }
 
+impl From<Result<StateChangeSuccess, StateChangeError>> for StateChangeReturn {
+    fn from(res: Result<StateChangeSuccess, StateChangeError>) -> Self {
+        match res {
+            Ok(success) => StateChangeReturn::from_ok(success),
+            Err(error) => StateChangeReturn::from_error(error),
+        }
+    }
+}
+
 impl FlowReturn {
     pub fn into_result(self) -> Result<FlowSuccess, FlowError> {
         match self {
@@ -186,6 +195,15 @@ impl Error for FlowError {
     }
 }
 
+impl From<Result<FlowSuccess, FlowError>> for FlowReturn {
+    fn from(res: Result<FlowSuccess, FlowError>) -> Self {
+        match res {
+            Ok(success) => FlowReturn::from_ok(success),
+            Err(error) => FlowReturn::from_error(error),
+        }
+    }
+}
+
 impl PadLinkReturn {
     pub fn into_result(self) -> Result<PadLinkSuccess, PadLinkError> {
         match self {
@@ -261,6 +279,15 @@ impl Error for PadLinkError {
     }
 }
 
+impl From<Result<PadLinkSuccess, PadLinkError>> for PadLinkReturn {
+    fn from(res: Result<PadLinkSuccess, PadLinkError>) -> Self {
+        match res {
+            Ok(success) => PadLinkReturn::from_ok(success),
+            Err(error) => PadLinkReturn::from_error(error),
+        }
+    }
+}
+
 impl ClockReturn {
     pub fn into_result(self) -> Result<ClockSuccess, ClockError> {
         match self {
@@ -343,6 +370,15 @@ impl Error for ClockError {
     }
 }
 
+impl From<Result<ClockSuccess, ClockError>> for ClockReturn {
+    fn from(res: Result<ClockSuccess, ClockError>) -> Self {
+        match res {
+            Ok(success) => ClockReturn::from_ok(success),
+            Err(error) => ClockReturn::from_error(error),
+        }
+    }
+}
+
 impl PartialOrd for ::TypeFindProbability {
     fn partial_cmp(&self, other: &Self) -> Option<cmp::Ordering> {
         self.to_glib().partial_cmp(&other.to_glib())

gstreamer/src/pad.rs

@@ -12,10 +12,15 @@ use BufferList;
 use Event;
 use FlowError;
 use FlowReturn;
+use FlowSuccess;
 use Format;
 use FormattedValue;
 use GenericFormattedValue;
 use Pad;
+use PadLinkCheck;
+use PadLinkError;
+use PadLinkReturn;
+use PadLinkSuccess;
 use PadProbeReturn;
 use PadProbeType;
 use Query;
@@ -111,11 +116,11 @@ pub trait PadExtManual: 'static {
         F: Fn(&Pad, &mut PadProbeInfo) -> PadProbeReturn + Send + Sync + 'static;
     fn remove_probe(&self, id: PadProbeId);
 
-    fn chain(&self, buffer: Buffer) -> FlowReturn;
-    fn push(&self, buffer: Buffer) -> FlowReturn;
+    fn chain(&self, buffer: Buffer) -> Result<FlowSuccess, FlowError>;
+    fn push(&self, buffer: Buffer) -> Result<FlowSuccess, FlowError>;
 
-    fn chain_list(&self, list: BufferList) -> FlowReturn;
-    fn push_list(&self, list: BufferList) -> FlowReturn;
+    fn chain_list(&self, list: BufferList) -> Result<FlowSuccess, FlowError>;
+    fn push_list(&self, list: BufferList) -> Result<FlowSuccess, FlowError>;
 
     fn pull_range(&self, offset: u64, size: u32) -> Result<Buffer, FlowError>;
     fn get_range(&self, offset: u64, size: u32) -> Result<Buffer, FlowError>;
@@ -138,12 +143,21 @@ pub trait PadExtManual: 'static {
     fn push_event(&self, event: Event) -> bool;
     fn send_event(&self, event: Event) -> bool;
 
+    fn get_last_flow_return(&self) -> Result<FlowSuccess, FlowError>;
+
     fn iterate_internal_links(&self) -> ::Iterator<Pad>;
     fn iterate_internal_links_default<'a, P: IsA<::Object> + 'a, Q: Into<Option<&'a P>>>(
         &self,
         parent: Q,
     ) -> ::Iterator<Pad>;
 
+    fn link<P: IsA<Pad>>(&self, sinkpad: &P) -> Result<PadLinkSuccess, PadLinkError>;
+    fn link_full<P: IsA<Pad>>(
+        &self,
+        sinkpad: &P,
+        flags: PadLinkCheck,
+    ) -> Result<PadLinkSuccess, PadLinkError>;
+
     fn stream_lock(&self) -> StreamLock;
 
     fn set_activate_function<F>(&self, func: F)
@@ -156,11 +170,17 @@ pub trait PadExtManual: 'static {
 
     fn set_chain_function<F>(&self, func: F)
     where
-        F: Fn(&Pad, &Option<::Object>, ::Buffer) -> ::FlowReturn + Send + Sync + 'static;
+        F: Fn(&Pad, &Option<::Object>, ::Buffer) -> Result<FlowSuccess, FlowError>
+            + Send
+            + Sync
+            + 'static;
 
     fn set_chain_list_function<F>(&self, func: F)
     where
-        F: Fn(&Pad, &Option<::Object>, ::BufferList) -> ::FlowReturn + Send + Sync + 'static;
+        F: Fn(&Pad, &Option<::Object>, ::BufferList) -> Result<FlowSuccess, FlowError>
+            + Send
+            + Sync
+            + 'static;
 
     fn set_event_function<F>(&self, func: F)
     where
@@ -168,7 +188,10 @@ pub trait PadExtManual: 'static {
 
     fn set_event_full_function<F>(&self, func: F)
     where
-        F: Fn(&Pad, &Option<::Object>, ::Event) -> ::FlowReturn + Send + Sync + 'static;
+        F: Fn(&Pad, &Option<::Object>, ::Event) -> Result<FlowSuccess, FlowError>
+            + Send
+            + Sync
+            + 'static;
 
     fn set_getrange_function<F>(&self, func: F)
     where
@@ -183,7 +206,10 @@ pub trait PadExtManual: 'static {
 
     fn set_link_function<F>(&self, func: F)
     where
-        F: Fn(&Pad, &Option<::Object>, &Pad) -> ::PadLinkReturn + Send + Sync + 'static;
+        F: Fn(&Pad, &Option<::Object>, &Pad) -> Result<::PadLinkSuccess, ::PadLinkError>
+            + Send
+            + Sync
+            + 'static;
 
     fn set_query_function<F>(&self, func: F)
     where
@@ -233,6 +259,8 @@ pub trait PadExtManual: 'static {
         &self,
         func: F,
     );
+
+    fn store_sticky_event(&self, event: &Event) -> Result<FlowSuccess, FlowError>;
 }
 
 impl<O: IsA<Pad>> PadExtManual for O {
@@ -266,29 +294,37 @@ impl<O: IsA<Pad>> PadExtManual for O {
         }
     }
 
-    fn chain(&self, buffer: Buffer) -> FlowReturn {
-        unsafe { from_glib(ffi::gst_pad_chain(self.to_glib_none().0, buffer.into_ptr())) }
-    }
-
-    fn push(&self, buffer: Buffer) -> FlowReturn {
-        unsafe { from_glib(ffi::gst_pad_push(self.to_glib_none().0, buffer.into_ptr())) }
-    }
-
-    fn chain_list(&self, list: BufferList) -> FlowReturn {
+    fn chain(&self, buffer: Buffer) -> Result<FlowSuccess, FlowError> {
         unsafe {
-            from_glib(ffi::gst_pad_chain_list(
+            FlowReturn::from_glib(ffi::gst_pad_chain(self.to_glib_none().0, buffer.into_ptr()))
+                .into_result()
+        }
+    }
+
+    fn push(&self, buffer: Buffer) -> Result<FlowSuccess, FlowError> {
+        unsafe {
+            FlowReturn::from_glib(ffi::gst_pad_push(self.to_glib_none().0, buffer.into_ptr()))
+                .into_result()
+        }
+    }
+
+    fn chain_list(&self, list: BufferList) -> Result<FlowSuccess, FlowError> {
+        unsafe {
+            FlowReturn::from_glib(ffi::gst_pad_chain_list(
                 self.to_glib_none().0,
                 list.into_ptr(),
             ))
+            .into_result()
         }
     }
 
-    fn push_list(&self, list: BufferList) -> FlowReturn {
+    fn push_list(&self, list: BufferList) -> Result<FlowSuccess, FlowError> {
         unsafe {
-            from_glib(ffi::gst_pad_push_list(
+            FlowReturn::from_glib(ffi::gst_pad_push_list(
                 self.to_glib_none().0,
                 list.into_ptr(),
             ))
+            .into_result()
         }
     }
 
@@ -406,6 +442,12 @@ impl<O: IsA<Pad>> PadExtManual for O {
         }
     }
 
+    fn get_last_flow_return(&self) -> Result<FlowSuccess, FlowError> {
+        let ret: FlowReturn =
+            unsafe { from_glib(ffi::gst_pad_get_last_flow_return(self.to_glib_none().0)) };
+        ret.into_result()
+    }
+
     fn iterate_internal_links(&self) -> ::Iterator<Pad> {
         unsafe { from_glib_full(ffi::gst_pad_iterate_internal_links(self.to_glib_none().0)) }
     }
@@ -424,6 +466,31 @@ impl<O: IsA<Pad>> PadExtManual for O {
         }
     }
 
+    fn link<P: IsA<Pad>>(&self, sinkpad: &P) -> Result<PadLinkSuccess, PadLinkError> {
+        let ret: PadLinkReturn = unsafe {
+            from_glib(ffi::gst_pad_link(
+                self.to_glib_none().0,
+                sinkpad.to_glib_none().0,
+            ))
+        };
+        ret.into_result()
+    }
+
+    fn link_full<P: IsA<Pad>>(
+        &self,
+        sinkpad: &P,
+        flags: PadLinkCheck,
+    ) -> Result<PadLinkSuccess, PadLinkError> {
+        let ret: PadLinkReturn = unsafe {
+            from_glib(ffi::gst_pad_link_full(
+                self.to_glib_none().0,
+                sinkpad.to_glib_none().0,
+                flags.to_glib(),
+            ))
+        };
+        ret.into_result()
+    }
+
     fn stream_lock(&self) -> StreamLock {
         unsafe {
             let pad = self.to_glib_none().0;
@@ -469,11 +536,17 @@ impl<O: IsA<Pad>> PadExtManual for O {
 
     fn set_chain_function<F>(&self, func: F)
     where
-        F: Fn(&Pad, &Option<::Object>, ::Buffer) -> ::FlowReturn + Send + Sync + 'static,
+        F: Fn(&Pad, &Option<::Object>, ::Buffer) -> Result<FlowSuccess, FlowError>
+            + Send
+            + Sync
+            + 'static,
     {
         unsafe {
             let func_box: Box<
-                Fn(&Pad, &Option<::Object>, ::Buffer) -> ::FlowReturn + Send + Sync + 'static,
+                Fn(&Pad, &Option<::Object>, ::Buffer) -> Result<FlowSuccess, FlowError>
+                    + Send
+                    + Sync
+                    + 'static,
             > = Box::new(func);
             ffi::gst_pad_set_chain_function_full(
                 self.to_glib_none().0,
@@ -486,11 +559,17 @@ impl<O: IsA<Pad>> PadExtManual for O {
 
     fn set_chain_list_function<F>(&self, func: F)
     where
-        F: Fn(&Pad, &Option<::Object>, ::BufferList) -> ::FlowReturn + Send + Sync + 'static,
+        F: Fn(&Pad, &Option<::Object>, ::BufferList) -> Result<FlowSuccess, FlowError>
+            + Send
+            + Sync
+            + 'static,
     {
         unsafe {
             let func_box: Box<
-                Fn(&Pad, &Option<::Object>, ::BufferList) -> ::FlowReturn + Send + Sync + 'static,
+                Fn(&Pad, &Option<::Object>, ::BufferList) -> Result<FlowSuccess, FlowError>
+                    + Send
+                    + Sync
+                    + 'static,
             > = Box::new(func);
             ffi::gst_pad_set_chain_list_function_full(
                 self.to_glib_none().0,
@@ -520,11 +599,17 @@ impl<O: IsA<Pad>> PadExtManual for O {
 
     fn set_event_full_function<F>(&self, func: F)
     where
-        F: Fn(&Pad, &Option<::Object>, ::Event) -> ::FlowReturn + Send + Sync + 'static,
+        F: Fn(&Pad, &Option<::Object>, ::Event) -> Result<FlowSuccess, FlowError>
+            + Send
+            + Sync
+            + 'static,
     {
         unsafe {
             let func_box: Box<
-                Fn(&Pad, &Option<::Object>, ::Event) -> ::FlowReturn + Send + Sync + 'static,
+                Fn(&Pad, &Option<::Object>, ::Event) -> Result<FlowSuccess, FlowError>
+                    + Send
+                    + Sync
+                    + 'static,
             > = Box::new(func);
             ffi::gst_pad_set_event_full_function_full(
                 self.to_glib_none().0,
@@ -537,7 +622,7 @@ impl<O: IsA<Pad>> PadExtManual for O {
 
     fn set_getrange_function<F>(&self, func: F)
     where
-        F: Fn(&Pad, &Option<::Object>, u64, u32) -> Result<::Buffer, ::FlowError>
+        F: Fn(&Pad, &Option<::Object>, u64, u32) -> Result<::Buffer, FlowError>
             + Send
             + Sync
             + 'static,
@@ -545,7 +630,7 @@ impl<O: IsA<Pad>> PadExtManual for O {
         unsafe {
             #[cfg_attr(feature = "cargo-clippy", allow(type_complexity))]
             let func_box: Box<
-                Fn(&Pad, &Option<::Object>, u64, u32) -> Result<::Buffer, ::FlowError>
+                Fn(&Pad, &Option<::Object>, u64, u32) -> Result<::Buffer, FlowError>
                     + Send
                     + Sync
                     + 'static,
@@ -578,11 +663,17 @@ impl<O: IsA<Pad>> PadExtManual for O {
 
     fn set_link_function<F>(&self, func: F)
     where
-        F: Fn(&Pad, &Option<::Object>, &Pad) -> ::PadLinkReturn + Send + Sync + 'static,
+        F: Fn(&Pad, &Option<::Object>, &Pad) -> Result<::PadLinkSuccess, ::PadLinkError>
+            + Send
+            + Sync
+            + 'static,
     {
         unsafe {
             let func_box: Box<
-                Fn(&Pad, &Option<::Object>, &Pad) -> ::PadLinkReturn + Send + Sync + 'static,
+                Fn(&Pad, &Option<::Object>, &Pad) -> Result<::PadLinkSuccess, ::PadLinkError>
+                    + Send
+                    + Sync
+                    + 'static,
             > = Box::new(func);
             ffi::gst_pad_set_link_function_full(
                 self.to_glib_none().0,
@@ -910,6 +1001,16 @@ impl<O: IsA<Pad>> PadExtManual for O {
             ffi::gst_pad_sticky_events_foreach(self.to_glib_none().0, Some(trampoline), func_ptr);
         }
     }
+
+    fn store_sticky_event(&self, event: &Event) -> Result<FlowSuccess, FlowError> {
+        let ret: FlowReturn = unsafe {
+            from_glib(ffi::gst_pad_store_sticky_event(
+                self.to_glib_none().0,
+                event.to_glib_none().0,
+            ))
+        };
+        ret.into_result()
+    }
 }
 
 #[repr(C)]
@@ -1048,17 +1149,18 @@ unsafe extern "C" fn trampoline_chain_function(
     buffer: *mut ffi::GstBuffer,
 ) -> ffi::GstFlowReturn {
     #[cfg_attr(feature = "cargo-clippy", allow(transmute_ptr_to_ref))]
-    let func: &&(Fn(&Pad, &Option<::Object>, ::Buffer) -> ::FlowReturn
+    let func: &&(Fn(&Pad, &Option<::Object>, ::Buffer) -> Result<FlowSuccess, FlowError>
            + Send
            + Sync
            + 'static) = transmute((*pad).chaindata);
 
-    func(
+    let res: FlowReturn = func(
         &from_glib_borrow(pad),
         &from_glib_borrow(parent),
         from_glib_full(buffer),
     )
-    .to_glib()
+    .into();
+    res.to_glib()
 }
 
 unsafe extern "C" fn trampoline_chain_list_function(
@@ -1067,17 +1169,18 @@ unsafe extern "C" fn trampoline_chain_list_function(
     list: *mut ffi::GstBufferList,
 ) -> ffi::GstFlowReturn {
     #[cfg_attr(feature = "cargo-clippy", allow(transmute_ptr_to_ref))]
-    let func: &&(Fn(&Pad, &Option<::Object>, ::BufferList) -> ::FlowReturn
+    let func: &&(Fn(&Pad, &Option<::Object>, ::BufferList) -> Result<FlowSuccess, FlowError>
            + Send
            + Sync
            + 'static) = transmute((*pad).chainlistdata);
 
-    func(
+    let res: FlowReturn = func(
         &from_glib_borrow(pad),
         &from_glib_borrow(parent),
         from_glib_full(list),
     )
-    .to_glib()
+    .into();
+    res.to_glib()
 }
 
 unsafe extern "C" fn trampoline_event_function(
@@ -1103,15 +1206,18 @@ unsafe extern "C" fn trampoline_event_full_function(
     event: *mut ffi::GstEvent,
 ) -> ffi::GstFlowReturn {
     #[cfg_attr(feature = "cargo-clippy", allow(transmute_ptr_to_ref))]
-    let func: &&(Fn(&Pad, &Option<::Object>, ::Event) -> ::FlowReturn + Send + Sync + 'static) =
-        transmute((*pad).eventdata);
+    let func: &&(Fn(&Pad, &Option<::Object>, ::Event) -> Result<FlowSuccess, FlowError>
+           + Send
+           + Sync
+           + 'static) = transmute((*pad).eventdata);
 
-    func(
+    let res: FlowReturn = func(
         &from_glib_borrow(pad),
         &from_glib_borrow(parent),
         from_glib_full(event),
     )
-    .to_glib()
+    .into();
+    res.to_glib()
 }
 
 unsafe extern "C" fn trampoline_getrange_function(
@@ -1122,7 +1228,7 @@ unsafe extern "C" fn trampoline_getrange_function(
     buffer: *mut *mut ffi::GstBuffer,
 ) -> ffi::GstFlowReturn {
     #[cfg_attr(feature = "cargo-clippy", allow(transmute_ptr_to_ref))]
-    let func: &&(Fn(&Pad, &Option<::Object>, u64, u32) -> Result<::Buffer, ::FlowError>
+    let func: &&(Fn(&Pad, &Option<::Object>, u64, u32) -> Result<::Buffer, FlowError>
            + Send
            + Sync
            + 'static) = transmute((*pad).getrangedata);
@@ -1135,9 +1241,9 @@ unsafe extern "C" fn trampoline_getrange_function(
     ) {
         Ok(new_buffer) => {
             *buffer = new_buffer.into_ptr();
-            ::FlowReturn::Ok.to_glib()
+            FlowReturn::Ok.to_glib()
         }
-        Err(ret) => ::FlowReturn::from_error(ret).to_glib(),
+        Err(ret) => FlowReturn::from_error(ret).to_glib(),
     }
 }
 
@@ -1163,17 +1269,22 @@ unsafe extern "C" fn trampoline_link_function(
     peer: *mut ffi::GstPad,
 ) -> ffi::GstPadLinkReturn {
     #[cfg_attr(feature = "cargo-clippy", allow(transmute_ptr_to_ref))]
-    let func: &&(Fn(&Pad, &Option<::Object>, &::Pad) -> ::PadLinkReturn
+    let func: &&(Fn(
+        &Pad,
+        &Option<::Object>,
+        &::Pad,
+    ) -> Result<::PadLinkSuccess, ::PadLinkError>
            + Send
            + Sync
            + 'static) = transmute((*pad).linkdata);
 
-    func(
+    let res: ::PadLinkReturn = func(
         &from_glib_borrow(pad),
         &from_glib_borrow(parent),
         &from_glib_borrow(peer),
     )
-    .to_glib()
+    .into();
+    res.to_glib()
 }
 
 unsafe extern "C" fn trampoline_query_function(
@@ -1252,7 +1363,7 @@ mod tests {
             let mut buffers = buffers_clone.lock().unwrap();
             buffers.push(buffer);
 
-            ::FlowReturn::Ok
+            Ok(FlowSuccess::Ok)
         });
 
         pad.set_active(true).unwrap();
@@ -1261,7 +1372,7 @@ mod tests {
         let segment = ::FormattedSegment::<::ClockTime>::new();
         assert!(pad.send_event(::Event::new_segment(segment.as_ref()).build()));
 
-        assert_eq!(pad.chain(::Buffer::new()), ::FlowReturn::Ok);
+        assert_eq!(pad.chain(::Buffer::new()), Ok(FlowSuccess::Ok));
 
         let events = events.lock().unwrap();
         let buffers = buffers.lock().unwrap();

gstreamer/src/proxy_pad.rs

@@ -11,6 +11,7 @@ use Buffer;
 use BufferList;
 use FlowError;
 use FlowReturn;
+use FlowSuccess;
 use Object;
 use Pad;
 use ProxyPad;
@@ -25,34 +26,36 @@ impl ProxyPad {
         pad: &P,
         parent: R,
         buffer: Buffer,
-    ) -> FlowReturn {
+    ) -> Result<FlowSuccess, FlowError> {
         skip_assert_initialized!();
         let parent = parent.into();
         let parent = parent.to_glib_none();
-        unsafe {
+        let ret: FlowReturn = unsafe {
             from_glib(ffi::gst_proxy_pad_chain_default(
                 pad.to_glib_none().0 as *mut ffi::GstPad,
                 parent.0,
                 buffer.into_ptr(),
             ))
-        }
+        };
+        ret.into_result()
     }
 
     pub fn chain_list_default<'a, P: IsA<ProxyPad>, Q: IsA<Object> + 'a, R: Into<Option<&'a Q>>>(
         pad: &P,
         parent: R,
         list: BufferList,
-    ) -> FlowReturn {
+    ) -> Result<FlowSuccess, FlowError> {
         skip_assert_initialized!();
         let parent = parent.into();
         let parent = parent.to_glib_none();
-        unsafe {
+        let ret: FlowReturn = unsafe {
             from_glib(ffi::gst_proxy_pad_chain_list_default(
                 pad.to_glib_none().0 as *mut ffi::GstPad,
                 parent.0,
                 list.into_ptr(),
             ))
-        }
+        };
+        ret.into_result()
     }
 
     pub fn getrange_default<P: IsA<ProxyPad>, Q: IsA<Object>>(

gstreamer/src/subclass/element.rs

@@ -24,10 +24,16 @@ use Event;
 use PadTemplate;
 use QueryRef;
 use StateChange;
+use StateChangeError;
 use StateChangeReturn;
+use StateChangeSuccess;
 
 pub trait ElementImpl: ObjectImpl + Send + Sync + 'static {
-    fn change_state(&self, element: &::Element, transition: StateChange) -> StateChangeReturn {
+    fn change_state(
+        &self,
+        element: &::Element,
+        transition: StateChange,
+    ) -> Result<StateChangeSuccess, StateChangeError> {
         self.parent_change_state(element, transition)
     }
 
@@ -59,7 +65,7 @@ pub trait ElementImpl: ObjectImpl + Send + Sync + 'static {
         &self,
         element: &::Element,
         transition: StateChange,
-    ) -> StateChangeReturn {
+    ) -> Result<StateChangeSuccess, StateChangeError> {
         unsafe {
             let data = self.get_type_data();
             let parent_class = data.as_ref().get_parent_class() as *mut ffi::GstElementClass;
@@ -68,6 +74,7 @@ pub trait ElementImpl: ObjectImpl + Send + Sync + 'static {
                 .change_state
                 .map(|f| from_glib(f(element.to_glib_none().0, transition.to_glib())))
                 .unwrap_or(::StateChangeReturn::Success)
+                .into_result()
         }
     }
 
@@ -248,7 +255,7 @@ where
     };
 
     gst_panic_to_error!(&wrap, &instance.panicked(), fallback, {
-        imp.change_state(&wrap, transition)
+        imp.change_state(&wrap, transition).into()
     })
     .to_glib()
 }

tutorials/src/bin/basic-tutorial-1.rs

@@ -14,8 +14,9 @@ fn tutorial_main() {
     let pipeline = gst::parse_launch(&format!("playbin uri={}", uri)).unwrap();
 
     // Start playing
-    let ret = pipeline.set_state(gst::State::Playing);
-    assert_ne!(ret, gst::StateChangeReturn::Failure);
+    pipeline
+        .set_state(gst::State::Playing)
+        .expect("Unable to set the pipeline to the `Playing` state");
 
     // Wait until error or EOS
     let bus = pipeline.get_bus().unwrap();
@@ -38,8 +39,9 @@ fn tutorial_main() {
     }
 
     // Shutdown pipeline
-    let ret = pipeline.set_state(gst::State::Null);
-    assert_ne!(ret, gst::StateChangeReturn::Failure);
+    pipeline
+        .set_state(gst::State::Null)
+        .expect("Unable to set the pipeline to the `Null` state");
 }
 
 fn main() {

tutorials/src/bin/basic-tutorial-12.rs

@@ -19,8 +19,8 @@ fn tutorial_main() -> Result<(), Error> {
     let pipeline = gst::parse_launch(&format!("playbin uri={}", uri))?;
 
     // Start playing
-    let ret = pipeline.set_state(gst::State::Playing).into_result()?;
-    let is_live = ret == gst::StateChangeSuccess::NoPreroll;
+    let res = pipeline.set_state(gst::State::Playing)?;
+    let is_live = res == gst::StateChangeSuccess::NoPreroll;
 
     let main_loop = glib::MainLoop::new(None, false);
     let main_loop_clone = main_loop.clone();

tutorials/src/bin/basic-tutorial-2.rs

@@ -25,12 +25,9 @@ fn tutorial_main() {
     source.set_property_from_str("pattern", "smpte");
 
     // Start playing
-    let ret = pipeline.set_state(gst::State::Playing);
-    assert_ne!(
-        ret,
-        gst::StateChangeReturn::Failure,
-        "Unable to set the pipeline to the Playing state."
-    );
+    pipeline
+        .set_state(gst::State::Playing)
+        .expect("Unable to set the pipeline to the `Playing` state");
 
     // Wait until error or EOS
     let bus = pipeline.get_bus().unwrap();
@@ -51,12 +48,9 @@ fn tutorial_main() {
         }
     }
 
-    let ret = pipeline.set_state(gst::State::Null);
-    assert_ne!(
-        ret,
-        gst::StateChangeReturn::Failure,
-        "Unable to set the pipeline to the Null state."
-    );
+    pipeline
+        .set_state(gst::State::Null)
+        .expect("Unable to set the pipeline to the `Null` state");
 }
 
 fn main() {

tutorials/src/bin/basic-tutorial-3.rs

@@ -76,8 +76,8 @@ fn tutorial_main() {
             return;
         }
 
-        let ret = src_pad.link(&sink_pad);
-        if ret != gst::PadLinkReturn::Ok {
+        let res = src_pad.link(&sink_pad);
+        if !res.is_ok() {
             println!("Type is {} but link failed.", new_pad_type);
         } else {
             println!("Link succeeded (type {}).", new_pad_type);
@@ -85,12 +85,9 @@ fn tutorial_main() {
     });
 
     // Start playing
-    let ret = pipeline.set_state(gst::State::Playing);
-    assert_ne!(
-        ret,
-        gst::StateChangeReturn::Failure,
-        "Unable to set the pipeline to the Playing state."
-    );
+    pipeline
+        .set_state(gst::State::Playing)
+        .expect("Unable to set the pipeline to the `Playing` state");
 
     // Wait until error or EOS
     let bus = pipeline.get_bus().unwrap();
@@ -124,12 +121,9 @@ fn tutorial_main() {
         }
     }
 
-    let ret = pipeline.set_state(gst::State::Null);
-    assert_ne!(
-        ret,
-        gst::StateChangeReturn::Failure,
-        "Unable to set the pipeline to the Null state."
-    );
+    pipeline
+        .set_state(gst::State::Null)
+        .expect("Unable to set the pipeline to the `Null` state");
 }
 
 fn main() {

tutorials/src/bin/basic-tutorial-4.rs

@@ -32,8 +32,9 @@ fn tutorial_main() {
         .expect("Can't set uri property on playbin");
 
     // Start playing
-    let ret = playbin.set_state(gst::State::Playing);
-    assert_ne!(ret, gst::StateChangeReturn::Failure);
+    playbin
+        .set_state(gst::State::Playing)
+        .expect("Unable to set the playbin to the `Playing` state");
 
     // Listen to the bus
     let bus = playbin.get_bus().unwrap();
@@ -92,8 +93,10 @@ fn tutorial_main() {
     }
 
     // Shutdown pipeline
-    let ret = custom_data.playbin.set_state(gst::State::Null);
-    assert_ne!(ret, gst::StateChangeReturn::Failure);
+    custom_data
+        .playbin
+        .set_state(gst::State::Null)
+        .expect("Unable to set the playbin to the `Null` state");
 }
 
 fn handle_message(custom_data: &mut CustomData, msg: &gst::GstRc<gst::MessageRef>) {

tutorials/src/bin/basic-tutorial-5.rs

@@ -121,8 +121,7 @@ mod tutorial5 {
             let pipeline = &pipeline;
             pipeline
                 .set_state(gst::State::Playing)
-                .into_result()
-                .unwrap();
+                .expect("Unable to set the pipeline to the `Playing` state");
         });
 
         let pause_button = gtk::Button::new_from_icon_name(
@@ -134,8 +133,7 @@ mod tutorial5 {
             let pipeline = &pipeline;
             pipeline
                 .set_state(gst::State::Paused)
-                .into_result()
-                .unwrap();
+                .expect("Unable to set the pipeline to the `Paused` state");
         });
 
         let stop_button = gtk::Button::new_from_icon_name(
@@ -145,7 +143,9 @@ mod tutorial5 {
         let pipeline = playbin.clone();
         stop_button.connect_clicked(move |_| {
             let pipeline = &pipeline;
-            pipeline.set_state(gst::State::Ready).into_result().unwrap();
+            pipeline
+                .set_state(gst::State::Ready)
+                .expect("Unable to set the pipeline to the `Ready` state");
         });
 
         let slider = gtk::Scale::new_with_range(
@@ -372,7 +372,9 @@ mod tutorial5 {
                 // We just set the pipeline to READY (which stops playback).
                 gst::MessageView::Eos(..) => {
                     println!("End-Of-Stream reached.");
-                    pipeline.set_state(gst::State::Ready).into_result().unwrap();
+                    pipeline
+                        .set_state(gst::State::Ready)
+                        .expect("Unable to set the pipeline to the `Ready` state");
                 }
 
                 // This is called when an error message is posted on the bus
@@ -401,12 +403,13 @@ mod tutorial5 {
 
         playbin
             .set_state(gst::State::Playing)
-            .into_result()
-            .unwrap();
+            .expect("Unable to set the playbin to the `Playing` state");
 
         gtk::main();
         window.hide();
-        playbin.set_state(gst::State::Null).into_result().unwrap();
+        playbin
+            .set_state(gst::State::Null)
+            .expect("Unable to set the playbin to the `Null` state");
 
         bus.remove_signal_watch();
     }

tutorials/src/bin/basic-tutorial-6.rs

@@ -111,10 +111,10 @@ fn tutorial_main() {
     print_pad_capabilities(&sink, "sink");
 
     // Start playing
-    let ret = pipeline.set_state(gst::State::Playing);
-    if ret == gst::StateChangeReturn::Failure {
+    let res = pipeline.set_state(gst::State::Playing);
+    if res.is_err() {
         eprintln!(
-            "Unable to set the pipeline to the playing state (check the bus for error messages)."
+            "Unable to set the pipeline to the `Playing` state (check the bus for error messages)."
         )
     }
 
@@ -159,8 +159,9 @@ fn tutorial_main() {
     }
 
     // Shutdown pipeline
-    let ret = pipeline.set_state(gst::State::Null);
-    assert_ne!(ret, gst::StateChangeReturn::Failure);
+    pipeline
+        .set_state(gst::State::Null)
+        .expect("Unable to set the pipeline to the `Null` state");
 }
 
 fn main() {

tutorials/src/bin/basic-tutorial-7.rs

@@ -53,7 +53,7 @@ fn tutorial_main() {
         tee_audio_pad.get_name()
     );
     let queue_audio_pad = audio_queue.get_static_pad("sink").unwrap();
-    tee_audio_pad.link(&queue_audio_pad).into_result().unwrap();
+    tee_audio_pad.link(&queue_audio_pad).unwrap();
 
     let tee_video_pad = tee.get_request_pad("src_%u").unwrap();
     println!(
@@ -61,12 +61,11 @@ fn tutorial_main() {
         tee_video_pad.get_name()
     );
     let queue_video_pad = video_queue.get_static_pad("sink").unwrap();
-    tee_video_pad.link(&queue_video_pad).into_result().unwrap();
+    tee_video_pad.link(&queue_video_pad).unwrap();
 
     pipeline
         .set_state(gst::State::Playing)
-        .into_result()
-        .expect("Unable to set the pipeline to the Playing state.");
+        .expect("Unable to set the pipeline to the `Playing` state");
     let bus = pipeline.get_bus().unwrap();
     for msg in bus.iter_timed(gst::CLOCK_TIME_NONE) {
         use gst::MessageView;
@@ -87,8 +86,7 @@ fn tutorial_main() {
 
     pipeline
         .set_state(gst::State::Null)
-        .into_result()
-        .expect("Unable to set the pipeline to the Null state.");
+        .expect("Unable to set the pipeline to the `Null` state");
 }
 
 fn main() {

tutorials/src/bin/basic-tutorial-8.rs

@@ -108,7 +108,7 @@ fn main() {
         tee_audio_pad.get_name()
     );
     let queue_audio_pad = audio_queue.get_static_pad("sink").unwrap();
-    tee_audio_pad.link(&queue_audio_pad).into_result().unwrap();
+    tee_audio_pad.link(&queue_audio_pad).unwrap();
 
     let tee_video_pad = tee.get_request_pad("src_%u").unwrap();
     println!(
@@ -116,10 +116,10 @@ fn main() {
         tee_video_pad.get_name()
     );
     let queue_video_pad = video_queue.get_static_pad("sink").unwrap();
-    tee_video_pad.link(&queue_video_pad).into_result().unwrap();
+    tee_video_pad.link(&queue_video_pad).unwrap();
     let tee_app_pad = tee.get_request_pad("src_%u").unwrap();
     let queue_app_pad = app_queue.get_static_pad("sink").unwrap();
-    tee_app_pad.link(&queue_app_pad).into_result().unwrap();
+    tee_app_pad.link(&queue_app_pad).unwrap();
 
     // configure appsrc
     let info = AudioInfo::new(gst_audio::AudioFormat::S16le, SAMPLE_RATE, 1)
@@ -195,10 +195,7 @@ fn main() {
                     (data.appsrc.clone(), buffer)
                 };
 
-                match appsrc.push_buffer(buffer) {
-                    gst::FlowReturn::Ok => glib::Continue(true),
-                    _ => glib::Continue(false),
-                }
+                glib::Continue(appsrc.push_buffer(buffer).is_ok())
             }));
         }
     });
@@ -225,7 +222,7 @@ fn main() {
     appsink.connect_new_sample(move |_| {
         let data = match data_weak.upgrade() {
             Some(data) => data,
-            None => return gst::FlowReturn::Ok,
+            None => return Ok(gst::FlowSuccess::Ok),
         };
 
         let appsink = {
@@ -240,7 +237,7 @@ fn main() {
             let _ = io::stdout().flush();
         }
 
-        gst::FlowReturn::Ok
+        Ok(gst::FlowSuccess::Ok)
     });
 
     let main_loop = glib::MainLoop::new(None, false);
@@ -263,15 +260,13 @@ fn main() {
 
     pipeline
         .set_state(gst::State::Playing)
-        .into_result()
-        .expect("Unable to set the pipeline to the Playing state.");
+        .expect("Unable to set the pipeline to the `Playing` state.");
 
     main_loop.run();
 
     pipeline
         .set_state(gst::State::Null)
-        .into_result()
-        .expect("Unable to set the pipeline to the Null state.");
+        .expect("Unable to set the pipeline to the `Null` state.");
 
     bus.remove_signal_watch();
 }