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/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim: set ts=8 sts=2 et sw=2 tw=80: */
/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at */
#include "MediaTrackGraph.h"
#include "PrincipalHandle.h"
namespace mozilla {
class AudioSegment;
class MediaTrackGraph;
class MediaStreamVideoSink;
class VideoSegment;
* This is a base class for media graph thread listener callbacks locked to
* specific tracks. Override methods to be notified of audio or video data or
* changes in track state.
* All notification methods are called from the media graph thread. Overriders
* of these methods are responsible for all synchronization. Beware!
* These methods are called without the media graph monitor held, so
* reentry into media graph methods is possible, although very much discouraged!
* You should do something non-blocking and non-reentrant (e.g. dispatch an
* event to some thread) and return.
* The listener is not allowed to add/remove any listeners from the parent
* track.
* If a listener is attached to a track that has already ended, we guarantee
* to call NotifyEnded.
class MediaTrackListener {
* When a SourceMediaTrack has pulling enabled, and the MediaTrackGraph
* control loop is ready to pull, this gets called for each track in the
* SourceMediaTrack that is lacking data for the current iteration.
* A NotifyPull implementation is allowed to call the SourceMediaTrack
* methods that alter track data.
* It is not allowed to make other MediaTrack API calls, including
* calls to add or remove MediaTrackListeners. It is not allowed to
* block for any length of time.
* aEndOfAppendedData is the duration of the data that has already been
* appended to this track, in track time.
* aDesiredTime is the track time we should append data up to. Data
* beyond this point will not be played until NotifyPull runs again, so
* there's not much point in providing it. Note that if the track is blocked
* for some reason, then data before aDesiredTime may not be played
* immediately.
virtual void NotifyPull(MediaTrackGraph* aGraph, TrackTime aEndOfAppendedData,
TrackTime aDesiredTime) {}
virtual void NotifyQueuedChanges(MediaTrackGraph* aGraph,
TrackTime aTrackOffset,
const MediaSegment& aQueuedMedia) {}
virtual void NotifyPrincipalHandleChanged(
MediaTrackGraph* aGraph, const PrincipalHandle& aNewPrincipalHandle) {}
* Notify that the enabled state for the track this listener is attached to
* has changed.
* The enabled state here is referring to whether audio should be audible
* (enabled) or silent (not enabled); or whether video should be displayed as
* is (enabled), or black (not enabled).
virtual void NotifyEnabledStateChanged(MediaTrackGraph* aGraph,
bool aEnabled) {}
* Notify that the track output is advancing. aCurrentTrackTime is the number
* of samples that has been played out for this track in track time.
virtual void NotifyOutput(MediaTrackGraph* aGraph,
TrackTime aCurrentTrackTime) {}
* Notify that this track has been ended and all data has been played out.
virtual void NotifyEnded(MediaTrackGraph* aGraph) {}
* Notify that this track listener has been removed from the graph, either
* after shutdown or through MediaTrack::RemoveListener().
virtual void NotifyRemoved(MediaTrackGraph* aGraph) {}
virtual ~MediaTrackListener() = default;
* This is a base class for media graph thread listener direct callbacks from
* within AppendToTrack(). It is bound to a certain track and can only be
* installed on audio tracks. Once added to a track on any track in the graph,
* the graph will try to install it at that track's source of media data.
* This works for ForwardedInputTracks, which will forward the listener to the
* track's input track if it exists, or wait for it to be created before
* forwarding if it doesn't.
* Once it reaches a SourceMediaTrack, it can be successfully installed.
* Other types of tracks will fail installation since they are not supported.
* Note that this listener and others for the same track will still get
* NotifyQueuedChanges() callbacks from the MTG tread, so you must be careful
* to ignore them if this listener was successfully installed.
class DirectMediaTrackListener : public MediaTrackListener {
friend class SourceMediaTrack;
friend class ForwardedInputTrack;
* This will be called on any DirectMediaTrackListener added to a
* SourceMediaTrack when AppendToTrack() is called for the listener's bound
* track, using the thread of the AppendToTrack() caller. The MediaSegment
* will be the RawSegment (unresampled) if available in AppendToTrack().
* If the track is enabled at the source but has been disabled in one of the
* tracks in between the source and where it was originally added, aMedia
* will be a disabled version of the one passed to AppendToTrack() as well.
* Note that NotifyQueuedTrackChanges() calls will also still occur.
virtual void NotifyRealtimeTrackData(MediaTrackGraph* aGraph,
TrackTime aTrackOffset,
const MediaSegment& aMedia) {}
* When a direct listener is processed for installation by the
* MediaTrackGraph it will be notified with whether the installation was
* successful or not. The results of this installation are the following:
* While looking for the data source of this track, we found a MediaTrack
* that is not a SourceMediaTrack or a ForwardedInputTrack.
* This DirectMediaTrackListener already exists in the
* SourceMediaTrack.
* Installation was successful and this listener will start receiving
* NotifyRealtimeData on the next AppendData().
enum class InstallationResult {
virtual void NotifyDirectListenerInstalled(InstallationResult aResult) {}
virtual void NotifyDirectListenerUninstalled() {}
virtual ~DirectMediaTrackListener() = default;
void MirrorAndDisableSegment(AudioSegment& aFrom, AudioSegment& aTo);
void MirrorAndDisableSegment(VideoSegment& aFrom, VideoSegment& aTo,
DisabledTrackMode aMode);
void NotifyRealtimeTrackDataAndApplyTrackDisabling(MediaTrackGraph* aGraph,
TrackTime aTrackOffset,
MediaSegment& aMedia);
void IncreaseDisabled(DisabledTrackMode aMode);
void DecreaseDisabled(DisabledTrackMode aMode);
// Matches the number of disabled tracks to which this listener is attached.
// The number of tracks are those between the track where the listener was
// added and the SourceMediaTrack that is the source of the data reaching
// this listener.
Atomic<int32_t> mDisabledFreezeCount;
Atomic<int32_t> mDisabledBlackCount;
} // namespace mozilla