tor-browser

MediaSink.h (5879B)

---

/* -*- 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 http://mozilla.org/MPL/2.0/. */

#ifndef MediaSink_h_
#define MediaSink_h_

#include "MediaInfo.h"
#include "mozilla/MozPromise.h"
#include "mozilla/RefPtr.h"
#include "mozilla/dom/MediaDebugInfoBinding.h"
#include "nsISupportsImpl.h"

class AudioDeviceInfo;

namespace mozilla {

class TimeStamp;
class VideoFrameContainer;

/**
* A consumer of audio/video data which plays audio and video tracks and
* manages A/V sync between them.
*
* A typical sink sends audio/video outputs to the speaker and screen.
* However, there are also sinks which capture the output of an media element
* and send the output to a MediaStream.
*
* This class is used to move A/V sync management and audio/video rendering
* out of MDSM so it is possible for subclasses to do external rendering using
* specific hardware which is required by TV projects and CDM.
*
* Note this class is not thread-safe and should be called from the state
* machine thread only.
*/
class MediaSink {
public:
 NS_INLINE_DECL_THREADSAFE_REFCOUNTING(MediaSink);
 typedef mozilla::TrackInfo::TrackType TrackType;

 // EndedPromise needs to be a non-exclusive promise as it is shared between
 // both the AudioSink and VideoSink.
 typedef MozPromise<bool, nsresult, /* IsExclusive = */ false> EndedPromise;

 // Return a promise which is resolved when the track finishes
 // or null if no such track.
 // Must be called after Start().
 // Returns null if the TrackType does not exist or if Stop() has been called.
 virtual RefPtr<EndedPromise> OnEnded(TrackType aType) = 0;

 // Return the end time of the audio/video data that has been consumed
 // or 0 if no such track.
 // Must be called after playback starts.
 virtual media::TimeUnit GetEndTime(TrackType aType) const = 0;

 // Return playback position for the media data.
 // Since A/V sync is always maintained by this sink, there is no need to
 // specify whether we want to get audio or video position.
 // aTimeStamp returns the timeStamp corresponding to the returned position
 // which is used by the compositor to derive the render time of video frames.
 // Must be called after playback starts.
 virtual media::TimeUnit GetPosition(TimeStamp* aTimeStamp = nullptr) = 0;

 // Return true if there are data consumed but not played yet.
 // Can be called in any state.
 virtual bool HasUnplayedFrames(TrackType aType) const = 0;

 // Return the duration of data consumed but not played yet.
 // Can be called in any state.
 virtual media::TimeUnit UnplayedDuration(TrackType aType) const = 0;

 // Set volume of the audio track.
 // Do nothing if this sink has no audio track.
 // Can be called in any state.
 virtual void SetVolume(double aVolume) {}

 // Set the audio stream name.
 // Does nothing if this sink has no audio stream.
 // Can be called in any state.
 virtual void SetStreamName(const nsAString& aStreamName) {}

 // Set the playback rate.
 // Can be called in any state.
 virtual void SetPlaybackRate(double aPlaybackRate) {}

 // Whether to preserve pitch of the audio track.
 // Do nothing if this sink has no audio track.
 // Can be called in any state.
 virtual void SetPreservesPitch(bool aPreservesPitch) {}

 // Pause/resume the playback. Only work after playback starts.
 virtual void SetPlaying(bool aPlaying) = 0;

 // Set the audio output device.  aDevice == nullptr indicates the default
 // device.  The returned promise is resolved when the previous device is no
 // longer in use and an attempt to open the new device completes
 // (successfully or not) or is deemed unnecessary because the device is not
 // required for output at this time.  The promise will be resolved whether
 // or not opening the cubeb_stream succeeds because the aDevice is
 // considered the new underlying device and will be used when it becomes
 // available.
 virtual RefPtr<GenericPromise> SetAudioDevice(
     RefPtr<AudioDeviceInfo> aDevice) = 0;

 // Get the playback rate.
 // Can be called in any state.
 virtual double PlaybackRate() const = 0;

 // Single frame rendering operation may need to be done before playback
 // started (1st frame) or right after seek completed or playback stopped.
 // Do nothing if this sink has no video track. Can be called in any state.
 virtual void Redraw(const VideoInfo& aInfo) {};

 // Begin a playback session with the provided start time in the media data
 // and media info.  Must be called when playback is stopped.  aStartTime is
 // compared with MediaData::mTime and continues to increase when looping,
 // unless decoding is reset.
 virtual nsresult Start(const media::TimeUnit& aStartTime,
                        const MediaInfo& aInfo) = 0;

 // Finish a playback session.
 // Must be called after playback starts.
 virtual void Stop() = 0;

 // Return true if playback has started.
 // Can be called in any state.
 virtual bool IsStarted() const = 0;

 // Return true if playback is started and not paused otherwise false.
 // Can be called in any state.
 virtual bool IsPlaying() const = 0;

 // Called on the state machine thread to shut down the sink. All resources
 // allocated by this sink should be released.
 // Must be called after playback stopped.
 virtual void Shutdown() {}

 virtual void SetSecondaryVideoContainer(VideoFrameContainer* aSecondary) {}

 virtual void GetDebugInfo(dom::MediaSinkDebugInfo& aInfo) {}

 virtual void SetVideoQueueSendToCompositorSize(const uint32_t aSize) {}

protected:
 virtual ~MediaSink() = default;
};

}  // namespace mozilla

#endif  // MediaSink_h_