Refactor stream selection for seeking in FFmpegDemuxer

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 117 matching lines @@
 
   // Returns the total buffer size FFMpegDemuxerStream is holding onto.
   size_t MemoryUsage() const;
 
   TextKind GetTextKind() const;
 
   // Returns the value associated with |key| in the metadata for the avstream.
   // Returns an empty string if the key is not present.
   std::string GetMetadata(const char* key) const;
 
+  AVStream* av_stream() const { return stream_; }
+
+  base::TimeDelta start_time() const { return start_time_; }
+  void set_start_time(base::TimeDelta time) { start_time_ = time; }
+
  private:
   friend class FFmpegDemuxerTest;
 
   // Use FFmpegDemuxerStream::Create to construct.
   // Audio/Video streams must include their respective DecoderConfig. At most
   // one DecoderConfig should be provided (leaving the other nullptr). Both
   // configs should be null for text streams.
   FFmpegDemuxerStream(FFmpegDemuxer* demuxer,
                       AVStream* stream,
                       std::unique_ptr<AudioDecoderConfig> audio_config,
                       std::unique_ptr<VideoDecoderConfig> video_config);
 
   // Runs |read_cb_| if present with the front of |buffer_queue_|, calling
   // NotifyCapacityAvailable() if capacity is still available.
   void SatisfyPendingRead();
 
   // Converts an FFmpeg stream timestamp into a base::TimeDelta.
   static base::TimeDelta ConvertStreamTimestamp(const AVRational& time_base,
                                                 int64_t timestamp);
 
   // Resets any currently active bitstream converter.
   void ResetBitstreamConverter();
 
   // Create new bitstream converter, destroying active converter if present.
   void InitBitstreamConverter();
 
   FFmpegDemuxer* demuxer_;
   scoped_refptr<base::SingleThreadTaskRunner> task_runner_;
   AVStream* stream_;
+  base::TimeDelta start_time_;
   std::unique_ptr<AudioDecoderConfig> audio_config_;
   std::unique_ptr<VideoDecoderConfig> video_config_;
   Type type_;
   Liveness liveness_;
   base::TimeDelta duration_;
   bool end_of_stream_;
   base::TimeDelta last_packet_timestamp_;
   base::TimeDelta last_packet_duration_;
   Ranges<base::TimeDelta> buffered_ranges_;
   VideoRotation video_rotation_;
@@ skipping 132 matching lines @@
   scoped_refptr<MediaLog> media_log_;
 
   // Derived bitrate after initialization has completed.
   int bitrate_;
 
   // The first timestamp of the audio or video stream, whichever is lower.  This
   // is used to adjust timestamps so that external consumers always see a zero
   // based timeline.
   base::TimeDelta start_time_;
 
-  // The index and start time of the preferred streams for seeking.  Filled upon
-  // completion of OnFindStreamInfoDone().  Each info entry represents an index
-  // into |streams_| and the start time of that stream.
-  //
-  // Seek() will attempt to use |preferred_stream_for_seeking_| if the seek
-  // point occurs after its associated start time.  Otherwise it will use
-  // |fallback_stream_for_seeking_|.
-  typedef std::pair<int, base::TimeDelta> StreamSeekInfo;
-  StreamSeekInfo preferred_stream_for_seeking_;
-  StreamSeekInfo fallback_stream_for_seeking_;
+  // 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 not considered.
+  FFmpegDemuxerStream* FindPreferredStreamForSeeking(base::TimeDelta seek_time);
 
   // 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.
@@ skipping 11 matching lines @@
 
   // NOTE: Weak pointers must be invalidated before all other member variables.
   base::WeakPtrFactory<FFmpegDemuxer> weak_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(FFmpegDemuxer);
 };
 
 }  // namespace media
 
 #endif  // MEDIA_FILTERS_FFMPEG_DEMUXER_H_