| // Copyright 2014 The Chromium Authors. All rights reserved. |
| // Use of this source code is governed by a BSD-style license that can be |
| // found in the LICENSE file. |
| |
| #ifndef MEDIA_FILTERS_FRAME_PROCESSOR_H_ |
| #define MEDIA_FILTERS_FRAME_PROCESSOR_H_ |
| |
| #include <map> |
| |
| #include "base/basictypes.h" |
| #include "base/callback_forward.h" |
| #include "base/time/time.h" |
| #include "media/base/media_export.h" |
| #include "media/base/stream_parser.h" |
| #include "media/filters/chunk_demuxer.h" |
| |
| namespace media { |
| |
| class MseTrackBuffer; |
| |
| // Helper class that implements Media Source Extension's coded frame processing |
| // algorithm. |
| class MEDIA_EXPORT FrameProcessor { |
| public: |
| typedef base::Callback<void(base::TimeDelta)> UpdateDurationCB; |
| |
| // TODO(wolenetz/acolwell): Ensure that all TrackIds are coherent and unique |
| // for each track buffer. For now, special track identifiers are used for each |
| // of audio and video here, and text TrackIds are assumed to be non-negative. |
| // See http://crbug.com/341581. |
| enum { |
| kAudioTrackId = -2, |
| kVideoTrackId = -3 |
| }; |
| |
| explicit FrameProcessor(const UpdateDurationCB& update_duration_cb); |
| ~FrameProcessor(); |
| |
| // Get/set the current append mode, which if true means "sequence" and if |
| // false means "segments". |
| // See http://www.w3.org/TR/media-source/#widl-SourceBuffer-mode. |
| bool sequence_mode() { return sequence_mode_; } |
| void SetSequenceMode(bool sequence_mode); |
| |
| // Processes buffers in |audio_buffers|, |video_buffers|, and |text_map|. |
| // Returns true on success or false on failure which indicates decode error. |
| // |append_window_start| and |append_window_end| correspond to the MSE spec's |
| // similarly named source buffer attributes that are used in coded frame |
| // processing. |
| // |*new_media_segment| tracks whether the next buffers processed within the |
| // append window represent the start of a new media segment. This method may |
| // both use and update this flag. |
| // Uses |*timestamp_offset| according to the coded frame processing algorithm, |
| // including updating it as required in 'sequence' mode frame processing. |
| bool ProcessFrames(const StreamParser::BufferQueue& audio_buffers, |
| const StreamParser::BufferQueue& video_buffers, |
| const StreamParser::TextBufferQueueMap& text_map, |
| base::TimeDelta append_window_start, |
| base::TimeDelta append_window_end, |
| bool* new_media_segment, |
| base::TimeDelta* timestamp_offset); |
| |
| // Signals the frame processor to update its group start timestamp to be |
| // |timestamp_offset| if it is in sequence append mode. |
| void SetGroupStartTimestampIfInSequenceMode(base::TimeDelta timestamp_offset); |
| |
| // Adds a new track with unique track ID |id|. |
| // If |id| has previously been added, returns false to indicate error. |
| // Otherwise, returns true, indicating future ProcessFrames() will emit |
| // frames for the track |id| to |stream|. |
| bool AddTrack(StreamParser::TrackId id, ChunkDemuxerStream* stream); |
| |
| // Updates the internal mapping of TrackId to track buffer for the track |
| // buffer formerly associated with |old_id| to be associated with |new_id|. |
| // Returns false to indicate failure due to either no existing track buffer |
| // for |old_id| or collision with previous track buffer already mapped to |
| // |new_id|. Otherwise returns true. |
| bool UpdateTrack(StreamParser::TrackId old_id, StreamParser::TrackId new_id); |
| |
| // Sets the need random access point flag on all track buffers to true. |
| void SetAllTrackBuffersNeedRandomAccessPoint(); |
| |
| // Resets state for the coded frame processing algorithm as described in steps |
| // 2-5 of the MSE Reset Parser State algorithm described at |
| // http://www.w3.org/TR/media-source/#sourcebuffer-reset-parser-state |
| void Reset(); |
| |
| // Must be called when the audio config is updated. Used to manage when |
| // the preroll buffer is cleared and the allowed "fudge" factor between |
| // preroll buffers. |
| void OnPossibleAudioConfigUpdate(const AudioDecoderConfig& config); |
| |
| private: |
| typedef std::map<StreamParser::TrackId, MseTrackBuffer*> TrackBufferMap; |
| |
| // If |track_buffers_| contains |id|, returns a pointer to the associated |
| // MseTrackBuffer. Otherwise, returns NULL. |
| MseTrackBuffer* FindTrack(StreamParser::TrackId id); |
| |
| // Signals all track buffers' streams that a new media segment is starting |
| // with decode timestamp |segment_timestamp|. |
| void NotifyNewMediaSegmentStarting(DecodeTimestamp segment_timestamp); |
| |
| // Helper that signals each track buffer to append any processed, but not yet |
| // appended, frames to its stream. Returns true on success, or false if one or |
| // more of the appends failed. |
| bool FlushProcessedFrames(); |
| |
| // Handles partial append window trimming of |buffer|. Returns true if the |
| // given |buffer| can be partially trimmed or have preroll added; otherwise, |
| // returns false. |
| // |
| // If |buffer| overlaps |append_window_start|, the portion of |buffer| before |
| // |append_window_start| will be marked for post-decode discard. Further, if |
| // |audio_preroll_buffer_| exists and abuts |buffer|, it will be set as |
| // preroll on |buffer| and |audio_preroll_buffer_| will be cleared. If the |
| // preroll buffer does not abut |buffer|, it will be discarded unused. |
| // |
| // Likewise, if |buffer| overlaps |append_window_end|, the portion of |buffer| |
| // after |append_window_end| will be marked for post-decode discard. |
| // |
| // If |buffer| lies entirely before |append_window_start|, and thus would |
| // normally be discarded, |audio_preroll_buffer_| will be set to |buffer| and |
| // the method will return false. |
| bool HandlePartialAppendWindowTrimming( |
| base::TimeDelta append_window_start, |
| base::TimeDelta append_window_end, |
| const scoped_refptr<StreamParserBuffer>& buffer); |
| |
| // Helper that processes one frame with the coded frame processing algorithm. |
| // Returns false on error or true on success. |
| bool ProcessFrame(const scoped_refptr<StreamParserBuffer>& frame, |
| base::TimeDelta append_window_start, |
| base::TimeDelta append_window_end, |
| base::TimeDelta* timestamp_offset, |
| bool* new_media_segment); |
| |
| // TrackId-indexed map of each track's stream. |
| TrackBufferMap track_buffers_; |
| |
| // The last audio buffer seen by the frame processor that was removed because |
| // it was entirely before the start of the append window. |
| scoped_refptr<StreamParserBuffer> audio_preroll_buffer_; |
| |
| // The AudioDecoderConfig associated with buffers handed to ProcessFrames(). |
| AudioDecoderConfig current_audio_config_; |
| base::TimeDelta sample_duration_; |
| |
| // The AppendMode of the associated SourceBuffer. |
| // See SetSequenceMode() for interpretation of |sequence_mode_|. |
| // Per http://www.w3.org/TR/media-source/#widl-SourceBuffer-mode: |
| // Controls how a sequence of media segments are handled. This is initially |
| // set to false ("segments"). |
| bool sequence_mode_; |
| |
| // Tracks the MSE coded frame processing variable of same name. |
| // Initially kNoTimestamp(), meaning "unset". |
| base::TimeDelta group_start_timestamp_; |
| |
| // Tracks the MSE coded frame processing variable of same name. It stores the |
| // highest coded frame end timestamp across all coded frames in the current |
| // coded frame group. It is set to 0 when the SourceBuffer object is created |
| // and gets updated by ProcessFrames(). |
| base::TimeDelta group_end_timestamp_; |
| |
| UpdateDurationCB update_duration_cb_; |
| |
| DISALLOW_COPY_AND_ASSIGN(FrameProcessor); |
| }; |
| |
| } // namespace media |
| |
| #endif // MEDIA_FILTERS_FRAME_PROCESSOR_H_ |