Refactor FFmpegAudioDecoder output timestamp logic.

media/filters/ffmpeg_audio_decoder.h

Index: media/filters/ffmpeg_audio_decoder.h
diff --git a/media/filters/ffmpeg_audio_decoder.h b/media/filters/ffmpeg_audio_decoder.h
index 46af8f0b2340160d2378d512da9c8f2e6ae95522..26692f3e7fb2dadebc848ec3b28cbb54eb949e56 100644
--- a/media/filters/ffmpeg_audio_decoder.h
+++ b/media/filters/ffmpeg_audio_decoder.h
@@ -52,13 +52,7 @@ class MEDIA_EXPORT FFmpegAudioDecoder : public AudioDecoder {
   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);
+  base::TimeDelta GetNextOutputTimestamp() const;

[scherkus (not reviewing), 2012/07/26 01:43:08]

docs

[acolwell GONE FROM CHROMIUM, 2012/07/27 20:45:29]

Done.

 
   // This is !is_null() iff Initialize() hasn't been called.
   base::Callback<MessageLoop*()> message_loop_factory_cb_;
@@ -73,7 +67,10 @@ class MEDIA_EXPORT FFmpegAudioDecoder : public AudioDecoder {
   ChannelLayout channel_layout_;
   int samples_per_second_;
 
-  base::TimeDelta estimated_next_timestamp_;
+  int bytes_per_frame_;

[scherkus (not reviewing), 2012/07/26 01:43:08]

nit: I'd add one-liner comment describing what these 4 vars are for (calculating
output timestamps)

[acolwell GONE FROM CHROMIUM, 2012/07/27 20:45:29]

Done.

+  base::TimeDelta total_frames_base_;

[scherkus (not reviewing), 2012/07/26 01:43:08]

when I read "total_frames_base_" I thought it had something to do with frames
(i.e., int) but it's a time!

what about output_timestamp_base_, starting_output_timestamp_, etc?

[acolwell GONE FROM CHROMIUM, 2012/07/27 20:45:29]

Done.

+  int64 total_frames_decoded_;
+  base::TimeDelta last_input_timestamp_;
 
   // Holds decoded audio.
   AVFrame* av_frame_;