Fix seeking when the start time is non-zero.

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
 // 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_
 
 #include <string>
+#include <utility>
 #include <vector>
 
 #include "base/callback.h"
 #include "base/gtest_prod_util.h"
 #include "base/memory/scoped_vector.h"
 #include "base/threading/thread.h"
 #include "media/base/audio_decoder_config.h"
 #include "media/base/decoder_buffer.h"
 #include "media/base/decoder_buffer_queue.h"
 #include "media/base/demuxer.h"
@@ skipping 12 matching lines @@
 
 class MediaLog;
 class FFmpegDemuxer;
 class FFmpegGlue;
 class FFmpegH264ToAnnexBBitstreamConverter;
 
 typedef scoped_ptr<AVPacket, ScopedPtrAVFreePacket> ScopedAVPacket;
 
 class FFmpegDemuxerStream : public DemuxerStream {
  public:
-  // Keeps a copy of |demuxer| and initializes itself using information
-  // inside |stream|.  Both parameters must outlive |this|.
-  FFmpegDemuxerStream(FFmpegDemuxer* demuxer, AVStream* stream);
+  // Keeps a copy of |demuxer| and initializes itself using information inside
+  // |stream|.  Both parameters must outlive |this|.
+  // |discard_negative_timestamps| tells the DemuxerStream that all packets with
+  // negative timestamps should be marked for post-decode discard.  All decoded
+  // data before time zero will be discarded.
+  FFmpegDemuxerStream(FFmpegDemuxer* demuxer,
+                      AVStream* stream,
+                      bool discard_negative_timestamps);
   virtual ~FFmpegDemuxerStream();
 
   // Enqueues the given AVPacket. It is invalid to queue a |packet| after
   // SetEndOfStream() has been called.
   void EnqueuePacket(ScopedAVPacket packet);
 
   // Enters the end of stream state. After delivering remaining queued buffers
   // only end of stream buffers will be delivered.
   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();
 
-  // Returns the duration of this stream.
-  base::TimeDelta duration();
+  base::TimeDelta duration() const { return duration_; }
 
   // DemuxerStream implementation.
   virtual Type type() OVERRIDE;
   virtual void Read(const ReadCB& read_cb) OVERRIDE;
   virtual void EnableBitstreamConverter() OVERRIDE;
   virtual bool SupportsConfigChanges() OVERRIDE;
   virtual AudioDecoderConfig audio_decoder_config() OVERRIDE;
   virtual VideoDecoderConfig video_decoder_config() OVERRIDE;
 
   // Returns the range of buffered data in this stream.
@@ skipping 40 matching lines @@
   DecoderBufferQueue buffer_queue_;
   ReadCB read_cb_;
 
 #if defined(USE_PROPRIETARY_CODECS)
   scoped_ptr<FFmpegH264ToAnnexBBitstreamConverter> bitstream_converter_;
 #endif
 
   bool bitstream_converter_enabled_;
 
   std::string encryption_key_id_;
+  const bool discard_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 NeedKeyCB& need_key_cb,
                 const scoped_refptr<MediaLog>& media_log);
   virtual ~FFmpegDemuxer();
 
   // Demuxer implementation.
   virtual void Initialize(DemuxerHost* host,
                           const PipelineStatusCB& status_cb,
                           bool enable_text_tracks) OVERRIDE;
   virtual void Stop(const base::Closure& callback) OVERRIDE;
   virtual void Seek(base::TimeDelta time, const PipelineStatusCB& cb) OVERRIDE;
   virtual DemuxerStream* GetStream(DemuxerStream::Type type) OVERRIDE;
-  virtual base::TimeDelta GetStartTime() const OVERRIDE;
   virtual base::Time GetTimelineOffset() const OVERRIDE;
   virtual Liveness GetLiveness() const OVERRIDE;
 
   // Calls |need_key_cb_| with the initialization data encountered in the file.
   void FireNeedKey(const std::string& init_data_type,
                    const std::string& encryption_key_id);
 
   // Allow FFmpegDemuxerStream to notify us when there is updated information
   // about capacity and what buffered data is available.
   void NotifyCapacityAvailable();
   void NotifyBufferingChanged();
 
+  // The lowest demuxed timestamp.  DemuxerStream's must use this to adjust
+  // packet timestamps such that external clients see a zero-based timeline.
+  base::TimeDelta start_time() const { return start_time_; }
+
  private:
   // To allow tests access to privates.
   friend class FFmpegDemuxerTest;
 
   // FFmpeg callbacks during initialization.
   void OnOpenContextDone(const PipelineStatusCB& status_cb, bool result);
   void OnFindStreamInfoDone(const PipelineStatusCB& status_cb, int result);
 
   // FFmpeg callbacks during seeking.
   void OnSeekFrameDone(const PipelineStatusCB& cb, int result);
@@ skipping 36 matching lines @@
   // 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.
   bool pending_seek_;
 
-  // |streams_| mirrors the AVStream array in |format_context_|. It contains
+  // |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.
   typedef ScopedVector<FFmpegDemuxerStream> StreamVector;
   StreamVector streams_;
 
   // Provides asynchronous IO to this demuxer. Consumed by |url_protocol_| to
   // integrate with libavformat.
   DataSource* data_source_;
 
   scoped_refptr<MediaLog> media_log_;
 
   // Derived bitrate after initialization has completed.
   int bitrate_;
 
-  // The first timestamp of the opened media file. This is used to set the
-  // starting clock value to match the timestamps in the media file. Default
-  // is 0.
+  // 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_;
+
   // 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_;
 
   // Liveness of the stream.
   Liveness liveness_;
 
   // 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_;
 
   // FFmpegURLProtocol implementation and corresponding glue bits.
   scoped_ptr<BlockingUrlProtocol> url_protocol_;
   scoped_ptr<FFmpegGlue> glue_;
 
   const NeedKeyCB need_key_cb_;
 
   // 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_