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+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim:set ts=2 sw=2 sts=2 et cindent: */
+/* 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/. */
+#if !defined(MediaDecoderStateMachine_h__)
+# define MediaDecoderStateMachine_h__
+
+# include "AudioDeviceInfo.h"
+# include "ImageContainer.h"
+# include "MediaDecoder.h"
+# include "MediaDecoderOwner.h"
+# include "MediaDecoderStateMachineBase.h"
+# include "MediaFormatReader.h"
+# include "MediaQueue.h"
+# include "MediaSink.h"
+# include "MediaStatistics.h"
+# include "MediaTimer.h"
+# include "SeekJob.h"
+# include "mozilla/Attributes.h"
+# include "mozilla/ReentrantMonitor.h"
+# include "mozilla/StateMirroring.h"
+# include "nsThreadUtils.h"
+
+namespace mozilla {
+
+class AbstractThread;
+class AudioSegment;
+class DecodedStream;
+class DOMMediaStream;
+class ReaderProxy;
+class TaskQueue;
+
+extern LazyLogModule gMediaDecoderLog;
+
+DDLoggedTypeDeclName(MediaDecoderStateMachine);
+
+/*
+
+Each media element for a media file has one thread called the "audio thread".
+
+The audio thread writes the decoded audio data to the audio
+hardware. This is done in a separate thread to ensure that the
+audio hardware gets a constant stream of data without
+interruption due to decoding or display. At some point
+AudioStream will be refactored to have a callback interface
+where it asks for data and this thread will no longer be
+needed.
+
+The element/state machine also has a TaskQueue which runs in a
+SharedThreadPool that is shared with all other elements/decoders. The state
+machine dispatches tasks to this to call into the MediaDecoderReader to
+request decoded audio or video data. The Reader will callback with decoded
+sampled when it has them available, and the state machine places the decoded
+samples into its queues for the consuming threads to pull from.
+
+The MediaDecoderReader can choose to decode asynchronously, or synchronously
+and return requested samples synchronously inside it's Request*Data()
+functions via callback. Asynchronous decoding is preferred, and should be
+used for any new readers.
+
+Synchronisation of state between the thread is done via a monitor owned
+by MediaDecoder.
+
+The lifetime of the audio thread is controlled by the state machine when
+it runs on the shared state machine thread. When playback needs to occur
+the audio thread is created and an event dispatched to run it. The audio
+thread exits when audio playback is completed or no longer required.
+
+A/V synchronisation is handled by the state machine. It examines the audio
+playback time and compares this to the next frame in the queue of video
+frames. If it is time to play the video frame it is then displayed, otherwise
+it schedules the state machine to run again at the time of the next frame.
+
+Frame skipping is done in the following ways:
+
+ 1) The state machine will skip all frames in the video queue whose
+ display time is less than the current audio time. This ensures
+ the correct frame for the current time is always displayed.
+
+ 2) The decode tasks will stop decoding interframes and read to the
+ next keyframe if it determines that decoding the remaining
+ interframes will cause playback issues. It detects this by:
+ a) If the amount of audio data in the audio queue drops
+ below a threshold whereby audio may start to skip.
+ b) If the video queue drops below a threshold where it
+ will be decoding video data that won't be displayed due
+ to the decode thread dropping the frame immediately.
+ TODO: In future we should only do this when the Reader is decoding
+ synchronously.
+
+When hardware accelerated graphics is not available, YCbCr conversion
+is done on the decode task queue when video frames are decoded.
+
+The decode task queue pushes decoded audio and videos frames into two
+separate queues - one for audio and one for video. These are kept
+separate to make it easy to constantly feed audio data to the audio
+hardware while allowing frame skipping of video data. These queues are
+threadsafe, and neither the decode, audio, or state machine should
+be able to monopolize them, and cause starvation of the other threads.
+
+Both queues are bounded by a maximum size. When this size is reached
+the decode tasks will no longer request video or audio depending on the
+queue that has reached the threshold. If both queues are full, no more
+decode tasks will be dispatched to the decode task queue, so other
+decoders will have an opportunity to run.
+
+During playback the audio thread will be idle (via a Wait() on the
+monitor) if the audio queue is empty. Otherwise it constantly pops
+audio data off the queue and plays it with a blocking write to the audio
+hardware (via AudioStream).
+
+*/
+class MediaDecoderStateMachine
+ : public MediaDecoderStateMachineBase,
+ public DecoderDoctorLifeLogger<MediaDecoderStateMachine> {
+ NS_INLINE_DECL_THREADSAFE_REFCOUNTING(MediaDecoderStateMachine, override)
+
+ using TrackSet = MediaFormatReader::TrackSet;
+
+ public:
+ using FrameID = mozilla::layers::ImageContainer::FrameID;
+ MediaDecoderStateMachine(MediaDecoder* aDecoder, MediaFormatReader* aReader);
+
+ nsresult Init(MediaDecoder* aDecoder) override;
+
+ // Enumeration for the valid decoding states
+ enum State {
+ DECODER_STATE_DECODING_METADATA,
+ DECODER_STATE_DORMANT,
+ DECODER_STATE_DECODING_FIRSTFRAME,
+ DECODER_STATE_DECODING,
+ DECODER_STATE_LOOPING_DECODING,
+ DECODER_STATE_SEEKING_ACCURATE,
+ DECODER_STATE_SEEKING_FROMDORMANT,
+ DECODER_STATE_SEEKING_NEXTFRAMESEEKING,
+ DECODER_STATE_SEEKING_VIDEOONLY,
+ DECODER_STATE_BUFFERING,
+ DECODER_STATE_COMPLETED,
+ DECODER_STATE_SHUTDOWN
+ };
+
+ RefPtr<GenericPromise> RequestDebugInfo(
+ dom::MediaDecoderStateMachineDebugInfo& aInfo) override;
+
+ size_t SizeOfVideoQueue() const override;
+
+ size_t SizeOfAudioQueue() const override;
+
+ // Sets the video decode mode. Used by the suspend-video-decoder feature.
+ void SetVideoDecodeMode(VideoDecodeMode aMode) override;
+
+ RefPtr<GenericPromise> InvokeSetSink(
+ const RefPtr<AudioDeviceInfo>& aSink) override;
+
+ void InvokeSuspendMediaSink() override;
+ void InvokeResumeMediaSink() override;
+
+ bool IsCDMProxySupported(CDMProxy* aProxy) override;
+
+ private:
+ class StateObject;
+ class DecodeMetadataState;
+ class DormantState;
+ class DecodingFirstFrameState;
+ class DecodingState;
+ class LoopingDecodingState;
+ class SeekingState;
+ class AccurateSeekingState;
+ class NextFrameSeekingState;
+ class NextFrameSeekingFromDormantState;
+ class VideoOnlySeekingState;
+ class BufferingState;
+ class CompletedState;
+ class ShutdownState;
+
+ static const char* ToStateStr(State aState);
+ const char* ToStateStr();
+
+ void GetDebugInfo(dom::MediaDecoderStateMachineDebugInfo& aInfo);
+
+ // Initialization that needs to happen on the task queue. This is the first
+ // task that gets run on the task queue, and is dispatched from the MDSM
+ // constructor immediately after the task queue is created.
+ void InitializationTask(MediaDecoder* aDecoder) override;
+
+ RefPtr<MediaDecoder::SeekPromise> Seek(const SeekTarget& aTarget) override;
+
+ RefPtr<ShutdownPromise> Shutdown() override;
+
+ RefPtr<ShutdownPromise> FinishShutdown();
+
+ // Update the playback position. This can result in a timeupdate event
+ // and an invalidate of the frame being dispatched asynchronously if
+ // there is no such event currently queued.
+ // Only called on the decoder thread. Must be called with
+ // the decode monitor held.
+ void UpdatePlaybackPosition(const media::TimeUnit& aTime);
+
+ // Schedules the shared state machine thread to run the state machine.
+ void ScheduleStateMachine();
+
+ // Invokes ScheduleStateMachine to run in |aTime|,
+ // unless it's already scheduled to run earlier, in which case the
+ // request is discarded.
+ void ScheduleStateMachineIn(const media::TimeUnit& aTime);
+
+ bool HaveEnoughDecodedAudio() const;
+ bool HaveEnoughDecodedVideo() const;
+
+ // The check is used to store more video frames than usual when playing 4K+
+ // video.
+ bool IsVideoDataEnoughComparedWithAudio() const;
+
+ // Returns true if we're currently playing. The decoder monitor must
+ // be held.
+ bool IsPlaying() const;
+
+ // Sets mMediaSeekable to false.
+ void SetMediaNotSeekable();
+
+ // Resets all states related to decoding and aborts all pending requests
+ // to the decoders.
+ void ResetDecode(const TrackSet& aTracks = TrackSet(TrackInfo::kAudioTrack,
+ TrackInfo::kVideoTrack));
+
+ void SetVideoDecodeModeInternal(VideoDecodeMode aMode);
+
+ RefPtr<GenericPromise> SetSink(RefPtr<AudioDeviceInfo> aDevice);
+
+ // Shutdown MediaSink on suspend to clean up resources.
+ void SuspendMediaSink();
+ // Create a new MediaSink, it must have been stopped first.
+ void ResumeMediaSink();
+
+ protected:
+ virtual ~MediaDecoderStateMachine();
+
+ void BufferedRangeUpdated() override;
+ void VolumeChanged() override;
+ void PreservesPitchChanged() override;
+ void PlayStateChanged() override;
+ void LoopingChanged() override;
+ void UpdateSecondaryVideoContainer() override;
+
+ void ReaderSuspendedChanged();
+
+ // Inserts a sample into the Audio/Video queue.
+ // aSample must not be null.
+ void PushAudio(AudioData* aSample);
+ void PushVideo(VideoData* aSample);
+
+ void OnAudioPopped(const RefPtr<AudioData>& aSample);
+ void OnVideoPopped(const RefPtr<VideoData>& aSample);
+
+ void AudioAudibleChanged(bool aAudible);
+
+ void SetPlaybackRate(double aPlaybackRate) override;
+ void SetIsLiveStream(bool aIsLiveStream) override {
+ mIsLiveStream = aIsLiveStream;
+ }
+ void SetCanPlayThrough(bool aCanPlayThrough) override {
+ mCanPlayThrough = aCanPlayThrough;
+ }
+ void SetFragmentEndTime(const media::TimeUnit& aEndTime) override {
+ // A negative number means we don't have a fragment end time at all.
+ mFragmentEndTime = aEndTime >= media::TimeUnit::Zero()
+ ? aEndTime
+ : media::TimeUnit::Invalid();
+ }
+
+ void StreamNameChanged();
+ void UpdateOutputCaptured();
+ void OutputPrincipalChanged();
+
+ MediaQueue<AudioData>& AudioQueue() { return mAudioQueue; }
+ MediaQueue<VideoData>& VideoQueue() { return mVideoQueue; }
+
+ const MediaQueue<AudioData>& AudioQueue() const { return mAudioQueue; }
+ const MediaQueue<VideoData>& VideoQueue() const { return mVideoQueue; }
+
+ // True if we are low in decoded audio/video data.
+ // May not be invoked when mReader->UseBufferingHeuristics() is false.
+ bool HasLowDecodedData();
+
+ bool HasLowDecodedAudio();
+
+ bool HasLowDecodedVideo();
+
+ bool OutOfDecodedAudio();
+
+ bool OutOfDecodedVideo() {
+ MOZ_ASSERT(OnTaskQueue());
+ return IsVideoDecoding() && VideoQueue().GetSize() <= 1;
+ }
+
+ // Returns true if we're running low on buffered data.
+ bool HasLowBufferedData();
+
+ // Returns true if we have less than aThreshold of buffered data available.
+ bool HasLowBufferedData(const media::TimeUnit& aThreshold);
+
+ // Return the current time, either the audio clock if available (if the media
+ // has audio, and the playback is possible), or a clock for the video.
+ // Called on the state machine thread.
+ // If aTimeStamp is non-null, set *aTimeStamp to the TimeStamp corresponding
+ // to the returned stream time.
+ media::TimeUnit GetClock(TimeStamp* aTimeStamp = nullptr) const;
+
+ // Update only the state machine's current playback position (and duration,
+ // if unknown). Does not update the playback position on the decoder or
+ // media element -- use UpdatePlaybackPosition for that. Called on the state
+ // machine thread, caller must hold the decoder lock.
+ void UpdatePlaybackPositionInternal(const media::TimeUnit& aTime);
+
+ // Update playback position and trigger next update by default time period.
+ // Called on the state machine thread.
+ void UpdatePlaybackPositionPeriodically();
+
+ MediaSink* CreateAudioSink();
+
+ // Always create mediasink which contains an AudioSink or DecodedStream
+ // inside.
+ already_AddRefed<MediaSink> CreateMediaSink();
+
+ // Stops the media sink and shut it down.
+ // The decoder monitor must be held with exactly one lock count.
+ // Called on the state machine thread.
+ void StopMediaSink();
+
+ // Create and start the media sink.
+ // The decoder monitor must be held with exactly one lock count.
+ // Called on the state machine thread.
+ // If start fails an NS_ERROR_FAILURE is returned.
+ nsresult StartMediaSink();
+
+ // Notification method invoked when mIsVisible changes.
+ void VisibilityChanged();
+
+ // Sets internal state which causes playback of media to pause.
+ // The decoder monitor must be held.
+ void StopPlayback();
+
+ // If the conditions are right, sets internal state which causes playback
+ // of media to begin or resume.
+ // Must be called with the decode monitor held.
+ void MaybeStartPlayback();
+
+ void EnqueueFirstFrameLoadedEvent();
+
+ // Start a task to decode audio.
+ void RequestAudioData();
+
+ // Start a task to decode video.
+ // @param aRequestNextVideoKeyFrame
+ // If aRequestNextKeyFrame is true, will request data for the next keyframe
+ // after aCurrentTime.
+ void RequestVideoData(const media::TimeUnit& aCurrentTime,
+ bool aRequestNextKeyFrame = false);
+
+ void WaitForData(MediaData::Type aType);
+
+ // Returns the "current playback position" in HTML5, which is in the range
+ // [0,duration]. The first frame of the media resource corresponds to 0
+ // regardless of any codec-specific internal time code.
+ media::TimeUnit GetMediaTime() const {
+ MOZ_ASSERT(OnTaskQueue());
+ return mCurrentPosition;
+ }
+
+ // Returns an upper bound on the number of microseconds of audio that is
+ // decoded and playable. This is the sum of the number of usecs of audio which
+ // is decoded and in the reader's audio queue, and the usecs of unplayed audio
+ // which has been pushed to the audio hardware for playback. Note that after
+ // calling this, the audio hardware may play some of the audio pushed to
+ // hardware, so this can only be used as a upper bound. The decoder monitor
+ // must be held when calling this. Called on the decode thread.
+ media::TimeUnit GetDecodedAudioDuration() const;
+
+ void FinishDecodeFirstFrame();
+
+ // Performs one "cycle" of the state machine.
+ void RunStateMachine();
+
+ bool IsStateMachineScheduled() const;
+
+ // These return true if the respective stream's decode has not yet reached
+ // the end of stream.
+ bool IsAudioDecoding();
+ bool IsVideoDecoding();
+
+ private:
+ // Resolved by the MediaSink to signal that all audio/video outstanding
+ // work is complete and identify which part(a/v) of the sink is shutting down.
+ void OnMediaSinkAudioComplete();
+ void OnMediaSinkVideoComplete();
+
+ // Rejected by the MediaSink to signal errors for audio/video.
+ void OnMediaSinkAudioError(nsresult aResult);
+ void OnMediaSinkVideoError();
+
+ // State-watching manager.
+ WatchManager<MediaDecoderStateMachine> mWatchManager;
+
+ // True if we've dispatched a task to run the state machine but the task has
+ // yet to run.
+ bool mDispatchedStateMachine;
+
+ // Used to dispatch another round schedule with specific target time.
+ DelayedScheduler mDelayedScheduler;
+
+ // Queue of audio frames. This queue is threadsafe, and is accessed from
+ // the audio, decoder, state machine, and main threads.
+ MediaQueue<AudioData> mAudioQueue;
+ // Queue of video frames. This queue is threadsafe, and is accessed from
+ // the decoder, state machine, and main threads.
+ MediaQueue<VideoData> mVideoQueue;
+
+ UniquePtr<StateObject> mStateObj;
+
+ media::TimeUnit Duration() const {
+ MOZ_ASSERT(OnTaskQueue());
+ return mDuration.Ref().ref();
+ }
+
+ // FrameID which increments every time a frame is pushed to our queue.
+ FrameID mCurrentFrameID;
+
+ // Media Fragment end time.
+ media::TimeUnit mFragmentEndTime = media::TimeUnit::Invalid();
+
+ // The media sink resource. Used on the state machine thread.
+ RefPtr<MediaSink> mMediaSink;
+
+ // The end time of the last audio frame that's been pushed onto the media sink
+ // in microseconds. This will approximately be the end time
+ // of the audio stream, unless another frame is pushed to the hardware.
+ media::TimeUnit AudioEndTime() const;
+
+ // The end time of the last rendered video frame that's been sent to
+ // compositor.
+ media::TimeUnit VideoEndTime() const;
+
+ // The end time of the last decoded audio frame. This signifies the end of
+ // decoded audio data. Used to check if we are low in decoded data.
+ media::TimeUnit mDecodedAudioEndTime;
+
+ // The end time of the last decoded video frame. Used to check if we are low
+ // on decoded video data.
+ media::TimeUnit mDecodedVideoEndTime;
+
+ // If we've got more than this number of decoded video frames waiting in
+ // the video queue, we will not decode any more video frames until some have
+ // been consumed by the play state machine thread.
+ // Must hold monitor.
+ uint32_t GetAmpleVideoFrames() const;
+
+ // Our "ample" audio threshold. Once we've this much audio decoded, we
+ // pause decoding.
+ media::TimeUnit mAmpleAudioThreshold;
+
+ const char* AudioRequestStatus() const;
+ const char* VideoRequestStatus() const;
+
+ void OnSuspendTimerResolved();
+ void CancelSuspendTimer();
+
+ bool IsInSeamlessLooping() const;
+
+ bool mCanPlayThrough = false;
+
+ bool mIsLiveStream = false;
+
+ // True if all audio frames are already rendered.
+ bool mAudioCompleted = false;
+
+ // True if all video frames are already rendered.
+ bool mVideoCompleted = false;
+
+ // True if video decoding is suspended.
+ bool mVideoDecodeSuspended;
+
+ // Track enabling video decode suspension via timer
+ DelayedScheduler mVideoDecodeSuspendTimer;
+
+ // Track the current video decode mode.
+ VideoDecodeMode mVideoDecodeMode;
+
+ // Track the complete & error for audio/video separately
+ MozPromiseRequestHolder<MediaSink::EndedPromise> mMediaSinkAudioEndedPromise;
+ MozPromiseRequestHolder<MediaSink::EndedPromise> mMediaSinkVideoEndedPromise;
+
+ MediaEventListener mAudioQueueListener;
+ MediaEventListener mVideoQueueListener;
+ MediaEventListener mAudibleListener;
+ MediaEventListener mOnMediaNotSeekable;
+
+ const bool mIsMSE;
+
+ const bool mShouldResistFingerprinting;
+
+ bool mSeamlessLoopingAllowed;
+
+ // If media was in looping and had reached to the end before, then we need
+ // to adjust sample time from clock time to media time.
+ void AdjustByLooping(media::TimeUnit& aTime) const;
+
+ // These are used for seamless looping. When looping has been enable at least
+ // once, `mOriginalDecodedDuration` would be set to the larger duration
+ // between two tracks.
+ media::TimeUnit mOriginalDecodedDuration;
+ Maybe<media::TimeUnit> mAudioTrackDecodedDuration;
+ Maybe<media::TimeUnit> mVideoTrackDecodedDuration;
+
+ bool HasLastDecodedData(MediaData::Type aType);
+
+ // Current playback position in the stream in bytes.
+ int64_t mPlaybackOffset = 0;
+
+ // For seamless looping video, we don't want to trigger skip-to-next-keyframe
+ // after reaching video EOS. Because we've reset the demuxer to 0, and are
+ // going to request data from start. If playback hasn't looped back, the media
+ // time would still be too large, which makes the reader think the playback is
+ // way behind and performs unnecessary skipping. Eg. Media is 10s long,
+ // reaching EOS at 8s, requesting data at 9s. Assume media's keyframe interval
+ // is 3s, which means keyframes will appear on 0s, 3s, 6s and 9s. If we use
+ // current time as a threshold, the reader sees the next key frame is 3s but
+ // the threashold is 9s, which usually happens when the decoding is too slow.
+ // But that is not the case for us, we should by pass thskip-to-next-keyframe
+ // logic until the media loops back.
+ bool mBypassingSkipToNextKeyFrameCheck = false;
+
+ private:
+ // Audio stream name
+ Mirror<nsAutoString> mStreamName;
+
+ // The device used with SetSink, or nullptr if no explicit device has been
+ // set.
+ Mirror<RefPtr<AudioDeviceInfo>> mSinkDevice;
+
+ // Whether all output should be captured into mOutputTracks, halted, or not
+ // captured.
+ Mirror<MediaDecoder::OutputCaptureState> mOutputCaptureState;
+
+ // A dummy track used to access the right MediaTrackGraph instance. Needed
+ // since there's no guarantee that output tracks are present.
+ Mirror<nsMainThreadPtrHandle<SharedDummyTrack>> mOutputDummyTrack;
+
+ // Tracks to capture data into.
+ Mirror<CopyableTArray<RefPtr<ProcessedMediaTrack>>> mOutputTracks;
+
+ // PrincipalHandle to feed with data captured into mOutputTracks.
+ Mirror<PrincipalHandle> mOutputPrincipal;
+
+ Canonical<PrincipalHandle> mCanonicalOutputPrincipal;
+
+ // Track when MediaSink is supsended. When that happens some actions are
+ // restricted like starting the sink or changing sink id. The flag is valid
+ // after Initialization. TaskQueue thread only.
+ bool mIsMediaSinkSuspended = false;
+
+ public:
+ AbstractCanonical<PrincipalHandle>* CanonicalOutputPrincipal() {
+ return &mCanonicalOutputPrincipal;
+ }
+};
+
+} // namespace mozilla
+
+#endif