Refactor FFmpegAudioDecoder output timestamp logic.

media/filters/ffmpeg_audio_decoder.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.
 
 #ifndef MEDIA_FILTERS_FFMPEG_AUDIO_DECODER_H_
 #define MEDIA_FILTERS_FFMPEG_AUDIO_DECODER_H_
 
 #include <list>
 
 #include "base/callback.h"
@@ skipping 34 matching lines @@
   void DoReset(const base::Closure& closure);
   void DoRead(const ReadCB& read_cb);
   void DoDecodeBuffer(DemuxerStream::Status status,
                       const scoped_refptr<DecoderBuffer>& input);
 
   // Reads from the demuxer stream with corresponding callback method.
   void ReadFromDemuxerStream();
   void DecodeBuffer(DemuxerStream::Status status,
                     const scoped_refptr<DecoderBuffer>& buffer);
 
-  // Updates the output buffer's duration and timestamp based on the input
-  // buffer. Will fall back to an estimated timestamp if the input lacks a
-  // valid timestamp.
-  void UpdateDurationAndTimestamp(const Buffer* input, DataBuffer* output);
-
-  // Calculates duration based on size of decoded audio bytes.
-  base::TimeDelta CalculateDuration(int size);
+  // Returns the timestamp that should be used for the next buffer returned
+  // via |read_cb_|. It is calculated from |output_timestamp_base_| and
+  // |total_frames_decoded_|.
+  base::TimeDelta GetNextOutputTimestamp() const;
 
   // This is !is_null() iff Initialize() hasn't been called.
   base::Callback<MessageLoop*()> message_loop_factory_cb_;
   MessageLoop* message_loop_;
 
   scoped_refptr<DemuxerStream> demuxer_stream_;
   StatisticsCB statistics_cb_;
   AVCodecContext* codec_context_;
 
   // Decoded audio format.
   int bits_per_channel_;
   ChannelLayout channel_layout_;
   int samples_per_second_;
 
-  base::TimeDelta estimated_next_timestamp_;
+  // Used for computing output timestamps.
+  int bytes_per_frame_;
+  base::TimeDelta output_timestamp_base_;
+  double total_frames_decoded_;
+  base::TimeDelta last_input_timestamp_;
+
+  // Number of output sample bytes to drop before generating
+  // output buffers.
+  int output_bytes_to_drop_;
 
   // Holds decoded audio.
   AVFrame* av_frame_;
 
   ReadCB read_cb_;
 
   DISALLOW_IMPLICIT_CONSTRUCTORS(FFmpegAudioDecoder);
 };
 
 }  // namespace media
 
 #endif  // MEDIA_FILTERS_FFMPEG_AUDIO_DECODER_H_