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// 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.
#include <map>
#include "base/callback_forward.h"
#include "base/macros.h"
#include "base/time/time.h"
#include "media/base/media_export.h"
#include "media/base/media_log.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 {
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
enum {
kAudioTrackId = -2,
kVideoTrackId = -3
FrameProcessor(const UpdateDurationCB& update_duration_cb,
const scoped_refptr<MediaLog>& media_log);
// Get/set the current append mode, which if true means "sequence" and if
// false means "segments".
// See
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.
// 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,
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
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);
friend class FrameProcessorTest;
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 coded frame group is starting
// with decode timestamp |start_timestamp|.
void NotifyStartOfCodedFrameGroup(DecodeTimestamp start_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);
// 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
// Controls how a sequence of media segments are handled. This is initially
// set to false ("segments").
bool sequence_mode_ = false;
// Flag to track whether or not the next processed frame is a continuation of
// a coded frame group. This flag resets to false upon detection of
// discontinuity, and becomes true once a processed coded frame for the
// current coded frame group is sent to its track buffer.
bool in_coded_frame_group_ = false;
// 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_;
// MediaLog for reporting messages and properties to debug content and engine.
scoped_refptr<MediaLog> media_log_;
// Counters that limit spam to |media_log_| for frame processor warnings.
int num_dropped_preroll_warnings_ = 0;
int num_dts_beyond_pts_warnings_ = 0;
} // namespace media