Enable seeking by dragging the time slider. Add a bunch of online clips to the hardcoded library.

gst-sdk/tutorials/xcode iOS/Tutorial 4/GStreamerBackend.h

@@ -22,4 +22,7 @@
 /* Set the URI to be played */
 -(void) setUri:(NSString*)uri;
 
+/* Set the position to seek to, in milliseconds */
+-(void) setPosition:(NSInteger)milliseconds;
+
 @end

gst-sdk/tutorials/xcode iOS/Tutorial 4/GStreamerBackend.m

@@ -7,6 +7,10 @@
 GST_DEBUG_CATEGORY_STATIC (debug_category);
 #define GST_CAT_DEFAULT debug_category
 
+/* Do not allow seeks to be performed closer than this distance. It is visually useless, and will probably
+ * confuse some demuxers. */
+#define SEEK_MIN_DELAY (500 * GST_MSECOND)
+
 @interface GStreamerBackend()
 -(void)setUIMessage:(gchar*) message;
 -(void)app_function;
@@ -14,15 +18,17 @@ GST_DEBUG_CATEGORY_STATIC (debug_category);
 @end
 
 @implementation GStreamerBackend {
-    id ui_delegate;        /* Class that we use to interact with the user interface */
+    id ui_delegate;              /* Class that we use to interact with the user interface */
-    GstElement *pipeline;  /* The running pipeline */
+    GstElement *pipeline;        /* The running pipeline */
-    GstElement *video_sink;/* The video sink element which receives XOverlay commands */
+    GstElement *video_sink;      /* The video sink element which receives XOverlay commands */
-    GMainContext *context; /* GLib context used to run the main loop */
+    GMainContext *context;       /* GLib context used to run the main loop */
-    GMainLoop *main_loop;  /* GLib main loop */
+    GMainLoop *main_loop;        /* GLib main loop */
-    gboolean initialized;  /* To avoid informing the UI multiple times about the initialization */
+    gboolean initialized;        /* To avoid informing the UI multiple times about the initialization */
-    UIView *ui_video_view; /* UIView that holds the video */
+    UIView *ui_video_view;       /* UIView that holds the video */
-    GstState state;        /* Current pipeline state */
+    GstState state;              /* Current pipeline state */
-    gint64 duration;       /* Cached clip duration */
+    gint64 duration;             /* Cached clip duration */
+    gint64 desired_position;     /* Position to seek to, once the pipeline is running */
+    GstClockTime last_seek_time; /* For seeking overflow prevention (throttling) */
 }
 
 /*
@@ -73,6 +79,17 @@ GST_DEBUG_CATEGORY_STATIC (debug_category);
     GST_DEBUG ("URI set to %s", char_uri);
 }
 
+-(void) setPosition:(NSInteger)milliseconds
+{
+    gint64 position = (gint64)(milliseconds * GST_MSECOND);
+    if (state >= GST_STATE_PAUSED) {
+        execute_seek(position, self);
+    } else {
+        GST_DEBUG ("Scheduling seek to %" GST_TIME_FORMAT " for later", GST_TIME_ARGS (position));
+        self->desired_position = position;
+    }
+}
+
 /*
  * Private methods
  */
@@ -108,9 +125,7 @@ static gboolean refresh_ui (GStreamerBackend *self) {
 
     /* If we didn't know it yet, query the stream duration */
     if (!GST_CLOCK_TIME_IS_VALID (self->duration)) {
-        if (!gst_element_query_duration (self->pipeline, &fmt, &self->duration)) {
+        gst_element_query_duration (self->pipeline, &fmt, &self->duration);
-            GST_WARNING ("Could not query current duration");
-        }
     }
 
     if (gst_element_query_position (self->pipeline, &fmt, &position)) {
@@ -120,6 +135,51 @@ static gboolean refresh_ui (GStreamerBackend *self) {
     return TRUE;
 }
 
+/* Forward declaration for the delayed seek callback */
+static gboolean delayed_seek_cb (GStreamerBackend *self);
+
+/* Perform seek, if we are not too close to the previous seek. Otherwise, schedule the seek for
+ * some time in the future. */
+static void execute_seek (gint64 position, GStreamerBackend *self) {
+    gint64 diff;
+
+    if (position == GST_CLOCK_TIME_NONE)
+        return;
+
+    diff = gst_util_get_timestamp () - self->last_seek_time;
+
+    if (GST_CLOCK_TIME_IS_VALID (self->last_seek_time) && diff < SEEK_MIN_DELAY) {
+        /* The previous seek was too close, delay this one */
+        GSource *timeout_source;
+
+        if (self->desired_position == GST_CLOCK_TIME_NONE) {
+            /* There was no previous seek scheduled. Setup a timer for some time in the future */
+            timeout_source = g_timeout_source_new ((SEEK_MIN_DELAY - diff) / GST_MSECOND);
+            g_source_set_callback (timeout_source, (GSourceFunc)delayed_seek_cb, (__bridge void *)self, NULL);
+            g_source_attach (timeout_source, self->context);
+            g_source_unref (timeout_source);
+        }
+        /* Update the desired seek position. If multiple petitions are received before it is time
+         * to perform a seek, only the last one is remembered. */
+        self->desired_position = position;
+        GST_DEBUG ("Throttling seek to %" GST_TIME_FORMAT ", will be in %" GST_TIME_FORMAT,
+                   GST_TIME_ARGS (position), GST_TIME_ARGS (SEEK_MIN_DELAY - diff));
+    } else {
+        /* Perform the seek now */
+        GST_DEBUG ("Seeking to %" GST_TIME_FORMAT, GST_TIME_ARGS (position));
+        self->last_seek_time = gst_util_get_timestamp ();
+        gst_element_seek_simple (self->pipeline, GST_FORMAT_TIME, GST_SEEK_FLAG_FLUSH | GST_SEEK_FLAG_KEY_UNIT, position);
+        self->desired_position = GST_CLOCK_TIME_NONE;
+    }
+}
+
+/* Delayed seek callback. This gets called by the timer setup in the above function. */
+static gboolean delayed_seek_cb (GStreamerBackend *self) {
+    GST_DEBUG ("Doing delayed seek to %" GST_TIME_FORMAT, GST_TIME_ARGS (self->desired_position));
+    execute_seek (self->desired_position, self);
+    return FALSE;
+}
+
 static void check_media_size (GStreamerBackend *self) {
     GstElement *video_sink;
     GstPad *video_sink_pad;
@@ -130,6 +190,10 @@ static void check_media_size (GStreamerBackend *self) {
 
     /* Retrieve the Caps at the entrance of the video sink */
     g_object_get (self->pipeline, "video-sink", &video_sink, NULL);
+
+    /* Do nothing if there is no video sink (this might be an audio-only clip */
+    if (!video_sink) return;
+
     video_sink_pad = gst_element_get_static_pad (video_sink, "sink");
     caps = gst_pad_get_negotiated_caps (video_sink_pad);
 
@@ -182,6 +246,10 @@ static void state_changed_cb (GstBus *bus, GstMessage *msg, GStreamerBackend *se
         if (old_state == GST_STATE_READY && new_state == GST_STATE_PAUSED)
         {
             check_media_size(self);
+
+            /* If there was a scheduled seek, perform it now that we have moved to the Paused state */
+            if (GST_CLOCK_TIME_IS_VALID (self->desired_position))
+                execute_seek (self->desired_position, self);
         }
     }
 }

gst-sdk/tutorials/xcode iOS/Tutorial 4/LibraryViewController.m

@@ -97,10 +97,31 @@ static NSString *CellIdentifier = @"CellIdentifier";
         [entries addObject:[NSString stringWithFormat:@"%@/%@",docsPath, e]];
     }
     self->mediaEntries = entries;
-    self->onlineEntries = [NSArray arrayWithObjects:
+
-        @"http://docs.gstreamer.com/media/sintel_trailer-368p.ogv",
+    entries = [[NSMutableArray alloc] init];
-        @"http://download.blender.org/peach/bigbuckbunny_movies/BigBuckBunny_640x360.m4v",
+
-        nil];
+    // Big Buck Bunny
+    [entries addObject:@"http://download.blender.org/peach/bigbuckbunny_movies/big_buck_bunny_480p_surround-fix.avi"];
+    [entries addObject:@"http://mirrorblender.top-ix.org/peach/bigbuckbunny_movies/big_buck_bunny_480p_h264.mov"];
+    [entries addObject:@"http://mirrorblender.top-ix.org/peach/bigbuckbunny_movies/big_buck_bunny_480p_stereo.ogg"];
+    [entries addObject:@"http://mirrorblender.top-ix.org/peach/bigbuckbunny_movies/big_buck_bunny_480p_stereo.avi"];
+
+    // Sintel
+    [entries addObject:@"http://ftp.nluug.nl/ftp/graphics/blender/apricot/trailer/Sintel_Trailer1.480p.DivX_Plus_HD.mkv"];
+    [entries addObject:@"http://ftp.nluug.nl/ftp/graphics/blender/apricot/trailer/sintel_trailer-480p.mp4"];
+    [entries addObject:@"http://ftp.nluug.nl/ftp/graphics/blender/apricot/trailer/sintel_trailer-480p.ogv"];
+    [entries addObject:@"http://mirrorblender.top-ix.org/movies/sintel-1024-surround.mp4"];
+
+    // Tears of Steel
+    [entries addObject:@"http://blender-mirror.kino3d.org/mango/download.blender.org/demo/movies/ToS/tears_of_steel_720p.mkv"];
+    [entries addObject:@"http://blender-mirror.kino3d.org/mango/download.blender.org/demo/movies/ToS/tears_of_steel_720p.mov"];
+    [entries addObject:@"http://media.xiph.org/mango/tears_of_steel_1080p.webm"];
+
+    // Radio stations
+    [entries addObject:@"http://radio.hbr1.com:19800/trance.ogg"];
+    [entries addObject:@"http://radio.hbr1.com:19800/tronic.aac"];
+
+    self->onlineEntries = entries;
 }
 
 @end

gst-sdk/tutorials/xcode iOS/Tutorial 4/VideoViewController.h

@@ -18,6 +18,9 @@
 
 -(IBAction) play:(id)sender;
 -(IBAction) pause:(id)sender;
+-(IBAction) sliderValueChanged:(id)sender;
+-(IBAction) sliderTouchDown:(id)sender;
+-(IBAction) sliderTouchUp:(id)sender;
 
 /* From GStreamerBackendDelegate */
 -(void) gstreamerInitialized;

gst-sdk/tutorials/xcode iOS/Tutorial 4/VideoViewController.m

@@ -6,6 +6,9 @@
     GStreamerBackend *gst_backend;
     int media_width;
     int media_height;
+    Boolean dragging_slider;
+    Boolean is_local_media;
+    Boolean is_playing_desired;
 }
 
 @end
@@ -56,7 +59,7 @@
     play_button.enabled = FALSE;
     pause_button.enabled = FALSE;
     
-    /* Make these constant for now, later tutorials will change them */
+    /* As soon as the GStreamer backend knows the real values, these ones will be replaced */
     media_width = 320;
     media_height = 240;
 
@@ -81,12 +84,37 @@
 -(IBAction) play:(id)sender
 {
     [gst_backend play];
+    is_playing_desired = YES;
 }
 
 /* Called when the Pause button is pressed */
 -(IBAction) pause:(id)sender
 {
     [gst_backend pause];
+    is_playing_desired = NO;
+}
+
+- (IBAction)sliderValueChanged:(id)sender {
+    if (!dragging_slider) return;
+    // If this is a local file, allow scrub seeking, this is, seek as soon as the slider is moved.
+    if (is_local_media)
+        [gst_backend setPosition:time_slider.value];
+    [self updateTimeWidget];
+}
+
+- (IBAction)sliderTouchDown:(id)sender {
+    [gst_backend pause];
+    dragging_slider = YES;
+}
+
+- (IBAction)sliderTouchUp:(id)sender {
+    dragging_slider = NO;
+    // If this is a remote file, scrub seeking is probably not going to work smoothly enough.
+    // Therefore, perform only the seek when the slider is released.
+    if (!is_local_media)
+        [gst_backend setPosition:time_slider.value];
+    if (is_playing_desired)
+        [gst_backend play];
 }
 
 /* Called when the size of the main view has changed, so we can
@@ -121,6 +149,8 @@
         pause_button.enabled = TRUE;
         message_label.text = @"Ready";
         [gst_backend setUri:uri];
+        is_local_media = [uri hasPrefix:@"file://"];
+        is_playing_desired = NO;
     });
 }
 
@@ -144,6 +174,9 @@
 
 -(void) setCurrentPosition:(NSInteger)position duration:(NSInteger)duration
 {
+    /* Ignore messages from the pipeline if the time sliders is being dragged */
+    if (dragging_slider) return;
+
     dispatch_async(dispatch_get_main_queue(), ^{
         time_slider.maximumValue = duration;
         time_slider.value = position;

gst-sdk/tutorials/xcode iOS/Tutorial 4/en.lproj/MainStoryboard_iPad.storyboard

@@ -80,6 +80,13 @@
                                         <slider key="customView" opaque="NO" contentMode="scaleToFill" contentHorizontalAlignment="center" contentVerticalAlignment="center" minValue="0.0" maxValue="1" id="ufs-E5-87w" userLabel="Slider">
                                             <rect key="frame" x="240" y="11" width="118" height="23"/>
                                             <autoresizingMask key="autoresizingMask" flexibleMaxX="YES" flexibleMaxY="YES"/>
+                                            <connections>
+                                                <action selector="sliderTouchDown:" destination="z7O-8l-Zeo" eventType="touchDown" id="yV6-eN-VUb"/>
+                                                <action selector="sliderTouchUp:" destination="z7O-8l-Zeo" eventType="touchCancel" id="OyS-WZ-sEk"/>
+                                                <action selector="sliderTouchUp:" destination="z7O-8l-Zeo" eventType="touchUpOutside" id="Vfz-se-pJg"/>
+                                                <action selector="sliderTouchUp:" destination="z7O-8l-Zeo" eventType="touchUpInside" id="kZF-uW-GRo"/>
+                                                <action selector="sliderValueChanged:" destination="z7O-8l-Zeo" eventType="valueChanged" id="cwm-pm-BfT"/>
+                                            </connections>
                                         </slider>
                                     </barButtonItem>
                                 </items>