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.
 //
 // FFmpegDemuxer sets the duration of pipeline during initialization by using
 // the duration of the longest audio/video stream.
 //
 // NOTE: since FFmpegDemuxer reads packets sequentially without seeking, media

[wolenetz, 2017/05/08 20:55:33]

this comment seems a bit incorrect now with this change.

 // files with very large drift between audio/video streams may result in
 // excessive memory consumption.
 //
 // When stopped, FFmpegDemuxer and FFmpegDemuxerStream release all callbacks
 // and buffered packets.  Reads from a stopped FFmpegDemuxerStream will not be
 // replied to.
 
 #ifndef MEDIA_FILTERS_FFMPEG_DEMUXER_H_
 #define MEDIA_FILTERS_FFMPEG_DEMUXER_H_
 
@@ skipping 239 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 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);
+
   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_;
@@ skipping 60 matching lines @@
   // 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_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_