mp4mux: Add support for edit lists

So we properly handle audio priming

Part-of: <https://gitlab.freedesktop.org/gstreamer/gst-plugins-rs/-/merge_requests/1434>

mux/fmp4/src/fmp4mux/boxes.rs

@@ -603,7 +603,7 @@ fn write_trak(
 
     // TODO: write edts optionally for negative DTS instead of offsetting the DTS
     write_box(v, b"mdia", |v| write_mdia(v, cfg, stream, creation_time))?;
-    if !stream.elst_infos.is_empty() {
+    if !stream.elst_infos.is_empty() && cfg.write_edts {
         if let Err(e) = write_edts(v, stream) {
             gst::warning!(CAT, "Failed to write edts: {e}");
         }

mux/fmp4/src/fmp4mux/imp.rs

@@ -26,6 +26,7 @@ use once_cell::sync::Lazy;
 use super::boxes;
 use super::Buffer;
 use super::DeltaFrames;
+use super::WriteEdtsMode;
 
 /// Offset for the segment in non-single-stream variants.
 const SEGMENT_OFFSET: gst::ClockTime = gst::ClockTime::from_seconds(60 * 60 * 1000);
@@ -106,6 +107,7 @@ const DEFAULT_WRITE_MFRA: bool = false;
 const DEFAULT_WRITE_MEHD: bool = false;
 const DEFAULT_INTERLEAVE_BYTES: Option<u64> = None;
 const DEFAULT_INTERLEAVE_TIME: Option<gst::ClockTime> = Some(gst::ClockTime::from_mseconds(250));
+const DEFAULT_WRITE_EDTS_MODE: WriteEdtsMode = WriteEdtsMode::Auto;
 
 #[derive(Debug, Clone)]
 struct Settings {
@@ -118,6 +120,7 @@ struct Settings {
     interleave_time: Option<gst::ClockTime>,
     movie_timescale: u32,
     offset_to_zero: bool,
+    write_edts_mode: WriteEdtsMode,
 }
 
 impl Default for Settings {
@@ -132,6 +135,7 @@ impl Default for Settings {
             interleave_time: DEFAULT_INTERLEAVE_TIME,
             movie_timescale: 0,
             offset_to_zero: false,
+            write_edts_mode: DEFAULT_WRITE_EDTS_MODE,
         }
     }
 }
@@ -3103,6 +3107,12 @@ impl FMP4Mux {
             })
             .collect::<Vec<_>>();
 
+        let write_edts = match settings.write_edts_mode {
+            WriteEdtsMode::Auto => self.obj().latency().is_none(),
+            WriteEdtsMode::Always => true,
+            WriteEdtsMode::Never => false,
+        };
+
         let mut buffer = boxes::create_fmp4_header(super::HeaderConfiguration {
             variant,
             update: at_eos,
@@ -3112,6 +3122,7 @@ impl FMP4Mux {
             duration: if at_eos { duration } else { None },
             language_code: state.language_code,
             orientation: state.orientation,
+            write_edts,
             start_utc_time: if variant == super::Variant::ONVIF {
                 state
                     .earliest_pts
@@ -3335,6 +3346,11 @@ impl ObjectImpl for FMP4Mux {
                     .blurb("Timescale to use for the movie (units per second, 0 is automatic)")
                     .mutable_ready()
                     .build(),
+                glib::ParamSpecEnum::builder_with_default("write-edts-mode", DEFAULT_WRITE_EDTS_MODE)
+                    .nick("Write edts mode")
+                    .blurb("Mode for writing EDTS, when in auto mode, edts written only for non-live streams.")
+                    .mutable_ready()
+                    .build(),
             ]
         });
 
@@ -3404,7 +3420,10 @@ impl ObjectImpl for FMP4Mux {
                 let mut settings = self.settings.lock().unwrap();
                 settings.movie_timescale = value.get().expect("type checked upstream");
             }
-
+            "write-edts-mode" => {
+                let mut settings = self.settings.lock().unwrap();
+                settings.write_edts_mode = value.get().expect("type checked upstream");
+            }
             _ => unimplemented!(),
         }
     }
@@ -3450,6 +3469,10 @@ impl ObjectImpl for FMP4Mux {
                 let settings = self.settings.lock().unwrap();
                 settings.movie_timescale.to_value()
             }
+            "write-edts-mode" => {
+                let settings = self.settings.lock().unwrap();
+                settings.write_edts_mode.to_value()
+            }
 
             _ => unimplemented!(),
         }

mux/fmp4/src/fmp4mux/mod.rs

@@ -44,6 +44,7 @@ pub fn register(plugin: &gst::Plugin) -> Result<(), glib::BoolError> {
         FMP4Mux::static_type().mark_as_plugin_api(gst::PluginAPIFlags::empty());
         FMP4MuxPad::static_type().mark_as_plugin_api(gst::PluginAPIFlags::empty());
         HeaderUpdateMode::static_type().mark_as_plugin_api(gst::PluginAPIFlags::empty());
+        WriteEdtsMode::static_type().mark_as_plugin_api(gst::PluginAPIFlags::empty());
     }
     gst::Element::register(
         Some(plugin),
@@ -167,6 +168,9 @@ pub(crate) struct HeaderConfiguration {
     /// Start UTC time in ONVIF mode.
     /// Since Jan 1 1601 in 100ns units.
     start_utc_time: Option<u64>,
+
+    /// Whether to write edts box
+    write_edts: bool,
 }
 
 #[derive(Debug, Clone)]
@@ -296,3 +300,12 @@ pub(crate) enum HeaderUpdateMode {
     Rewrite,
     Update,
 }
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq, glib::Enum, Default)]
+#[enum_type(name = "GstFMP4MuxWriteEdtsMode")]
+pub(crate) enum WriteEdtsMode {
+    #[default]
+    Auto,
+    Always,
+    Never,
+}

mux/mp4/src/mp4mux/imp.rs

@@ -347,7 +347,7 @@ impl MP4Mux {
 
         let generic_to_samples = move |t| -> Result<Option<u64>, anyhow::Error> {
             if let gst::GenericFormattedValue::Default(Some(v)) = t {
-                let v: u64 = v.into();
+                let v = u64::from(v);
                 Ok(Some(v).filter(|x| x != &0u64))
             } else if let gst::GenericFormattedValue::Time(Some(v)) = t {
                 Ok(Some(gstclocktime_to_samples(v)?))
@@ -356,8 +356,8 @@ impl MP4Mux {
             }
         };
 
-        let start: Option<u64> = generic_to_samples(cmeta.start())?;
-        let end: Option<u64> = generic_to_samples(cmeta.end())?;
+        let start = generic_to_samples(cmeta.start())?;
+        let end = generic_to_samples(cmeta.end())?;
 
         if end.is_none() && start.is_none() {
             return Err(anyhow!(