Fix incorrect opus seek preroll and flaky pre-skip removal.

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 59 matching lines @@
   void SetEndOfStream();
 
   // Drops queued buffers and clears end of stream state.
   void FlushBuffers();
 
   // Empties the queues and ignores any additional calls to Read().
   void Stop();
 
   base::TimeDelta duration() const { return duration_; }
 
-  // Enables fixes for ogg files with negative timestamps.  For AUDIO streams,
-  // all packets with negative timestamps will be marked for post-decode
-  // discard.  For all other stream types, if FFmpegDemuxer::start_time() is
-  // negative, it will not be used to shift timestamps during EnqueuePacket().
-  void enable_negative_timestamp_fixups_for_ogg() {
-    fixup_negative_ogg_timestamps_ = true;
+  // Enables fixes for files with negative timestamps.  Normally all timestamps
+  // are rebased against FFmpegDemuxer::start_time() whenever that value is
+  // negative.  When this fix is enabled, only AUDIO stream packets will be
+  // rebased to time zero, all other stream types will use the muxed timestamp.
+  //
+  // Further, when no codec delay is present, all AUDIO packets which originally
+  // had negative timestamps will be marked for post-decode discard.  When codec
+  // delay is present, it is assumed the decoder will handle discard and does
+  // not need the AUDIO packets to be marked for discard; just rebased to zero.
+  void enable_negative_timestamp_fixups() {
+    fixup_negative_timestamps_ = true;
   }
 
   // DemuxerStream implementation.
   Type type() const override;
   Liveness liveness() const override;
   void Read(const ReadCB& read_cb) override;
   void EnableBitstreamConverter() override;
   bool SupportsConfigChanges() override;
   AudioDecoderConfig audio_decoder_config() override;
   VideoDecoderConfig video_decoder_config() override;
@@ skipping 52 matching lines @@
   VideoRotation video_rotation_;
 
   DecoderBufferQueue buffer_queue_;
   ReadCB read_cb_;
 
 #if defined(USE_PROPRIETARY_CODECS)
   scoped_ptr<FFmpegBitstreamConverter> bitstream_converter_;
 #endif
 
   std::string encryption_key_id_;
-  bool fixup_negative_ogg_timestamps_;
+  bool fixup_negative_timestamps_;
 
   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 scoped_refptr<MediaLog>& media_log);
@@ skipping 136 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_