Use ffmpeg packet.pos for restarting reading after reenabling video

media/filters/ffmpeg_demuxer.h

 // Copyright (c) 2012 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.
 
 // Implements the Demuxer interface using FFmpeg's libavformat.  At this time
 // will support demuxing any audio/video format thrown at it.  The streams
 // output mime types audio/x-ffmpeg and video/x-ffmpeg and include an integer
 // key FFmpegCodecID which contains the CodecID enumeration value.  The CodecIDs
 // can be used to create and initialize the corresponding FFmpeg decoder.
 //
@@ skipping 182 matching lines @@
   ReadCB read_cb_;
   StreamStatusChangeCB stream_status_change_cb_;
 
 #if BUILDFLAG(USE_PROPRIETARY_CODECS)
   std::unique_ptr<FFmpegBitstreamConverter> bitstream_converter_;
 #endif
 
   std::string encryption_key_id_;
   bool fixup_negative_timestamps_;
 
+  base::TimeDelta stream_capacity_;
+
   DISALLOW_COPY_AND_ASSIGN(FFmpegDemuxerStream);
 };
 
 class MEDIA_EXPORT FFmpegDemuxer : public Demuxer {
  public:
   FFmpegDemuxer(const scoped_refptr<base::SingleThreadTaskRunner>& task_runner,
                 DataSource* data_source,
                 const EncryptedMediaInitDataCB& encrypted_media_init_data_cb,
                 const MediaTracksUpdatedCB& media_tracks_updated_cb,
                 MediaLog* media_log);
@@ skipping 51 matching lines @@
 
   // FFmpeg callbacks during initialization.
   void OnOpenContextDone(const PipelineStatusCB& status_cb, bool result);
   void OnFindStreamInfoDone(const PipelineStatusCB& status_cb, int result);
 
   void LogMetadata(AVFormatContext* avctx, base::TimeDelta max_duration);
 
   // FFmpeg callbacks during seeking.
   void OnSeekFrameDone(int result);
 
+  // Called when FFmpeg completes the seek initiated in
+  // OnSelectedVideoTrackChanged in order to restart the |stream|.
+  void OnSeekDoneForRestartingStream(FFmpegDemuxerStream* stream, int result);
+
   // FFmpeg callbacks during reading + helper method to initiate reads.
   void ReadFrameIfNeeded();
   void OnReadFrameDone(ScopedAVPacket packet, int result);
 
   // Returns true iff any stream has additional capacity. Note that streams can
   // go over capacity depending on how the file is muxed.
   bool StreamsHaveAvailableCapacity();
 
   // Returns true if the maximum allowed memory usage has been reached.
   bool IsMaxMemoryUsageReached() const;
 
   // Signal all FFmpegDemuxerStreams that the stream has ended.
   void StreamHasEnded();
 
   // Called by |url_protocol_| whenever |data_source_| returns a read error.
   void OnDataSourceError();
 
   // Returns the first stream from |streams_| that matches |type| as an
   // FFmpegDemuxerStream and is enabled.
   FFmpegDemuxerStream* GetFirstEnabledFFmpegStream(
       DemuxerStream::Type type) const;
 
   // Called after the streams have been collected from the media, to allow
   // the text renderer to bind each text stream to the cue rendering engine.
   void AddTextStreams();
 
   void SetLiveness(DemuxerStream::Liveness liveness);
 
+  // Do an FFmpeg seek such that the read position is adjusted to be able to
+  // restart playback from the |time| position. If the |preferred_stream| is not
+  // null then it is used for seeking, otherwise the preferred stream is
+  // selected by FindPreferredStreamForSeeking function. When the seek is
+  // completed the |ffmpeg_seek_done_cb| will be called with FFmpeg result.
+  using FFmpegSeekDoneCB = base::Callback<void(int ffmpeg_result)>;
+  void SeekInternal(base::TimeDelta time,
+                    FFmpegDemuxerStream* preferred_stream,
+                    const FFmpegSeekDoneCB& ffmpeg_seek_done_cb);

[DaleCurtis, 2017/05/24 22:24:18]

pass by value nowadays.

[servolk, 2017/05/24 22:58:20]

Done.

+
   DemuxerHost* host_;
 
   scoped_refptr<base::SingleThreadTaskRunner> task_runner_;
 
   // Task runner on which all blocking FFmpeg operations are executed; retrieved
   // from base::TaskScheduler.
   scoped_refptr<base::SequencedTaskRunner> blocking_task_runner_;
 
   // Indicates if Stop() has been called.
   bool stopped_;
 
   // Tracks if there's an outstanding av_read_frame() operation.
   //
   // TODO(scherkus): Allow more than one read in flight for higher read
   // throughput using demuxer_bench to verify improvements.
   bool pending_read_;
 
   // Tracks if there's an outstanding av_seek_frame() operation. Used to discard
   // results of pre-seek av_read_frame() operations.
   PipelineStatusCB pending_seek_cb_;
+  base::TimeDelta pending_seek_position_;
 
   // |streams_| mirrors the AVStream array in AVFormatContext. It contains
   // FFmpegDemuxerStreams encapsluating AVStream objects at the same index.
   //
   // Since we only support a single audio and video stream, |streams_| will
   // contain NULL entries for additional audio/video streams as well as for
   // stream types that we do not currently support.
   //
   // Once initialized, operations on FFmpegDemuxerStreams should be carried out
   // on the demuxer thread.
@@ skipping 18 matching lines @@
   // start time) with enabled status matching |enabled|.
   FFmpegDemuxerStream* FindStreamWithLowestStartTimestamp(bool enabled);
 
   // Finds a preferred stream for seeking to |seek_time|. Preference is
   // typically given to video streams, unless the |seek_time| is earlier than
   // the start time of the video stream. In that case a stream with the earliest
   // start time is preferred. Disabled streams are considered only as the last
   // fallback option.
   FFmpegDemuxerStream* FindPreferredStreamForSeeking(base::TimeDelta seek_time);
 
+  // Restarts a previous pending seek if a video stream got re-enabled while a
+  // pending seek was in progress.
+  void RestartPendingSeek(base::TimeDelta time,
+                          const PipelineStatusCB& cb,

[DaleCurtis, 2017/05/24 22:24:18]

Ditto.

+                          PipelineStatus prev_seek_status);
+
   // The Time associated with timestamp 0. Set to a null
   // time if the file doesn't have an association to Time.
   base::Time timeline_offset_;
 
   // Whether text streams have been enabled for this demuxer.
   bool text_enabled_;
 
   // Set if we know duration of the audio stream. Used when processing end of
   // stream -- at this moment we definitely know duration.
   bool duration_known_;
   base::TimeDelta duration_;
 
   // FFmpegURLProtocol implementation and corresponding glue bits.
   std::unique_ptr<BlockingUrlProtocol> url_protocol_;
   std::unique_ptr<FFmpegGlue> glue_;
 
   const EncryptedMediaInitDataCB encrypted_media_init_data_cb_;
 
   const MediaTracksUpdatedCB media_tracks_updated_cb_;
 
   std::map<MediaTrack::Id, FFmpegDemuxerStream*> track_id_to_demux_stream_map_;
 
+  int64_t last_audio_packet_pos_;
+  FFmpegDemuxerStream* restarting_stream_;
+
   // NOTE: Weak pointers must be invalidated before all other member variables.
   base::WeakPtr<FFmpegDemuxer> weak_this_;
   base::WeakPtrFactory<FFmpegDemuxer> cancel_pending_seek_factory_;
   base::WeakPtrFactory<FFmpegDemuxer> weak_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(FFmpegDemuxer);
 };
 
 }  // namespace media
 
 #endif  // MEDIA_FILTERS_FFMPEG_DEMUXER_H_