Make sure that DecodeAudioFileData() always returns an AudioBus of the exact length of the file

media/filters/audio_file_reader.h

 // Copyright (c) 2011 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_AUDIO_FILE_READER_H_
 #define MEDIA_FILTERS_AUDIO_FILE_READER_H_
 
 #include <vector>
 #include "media/filters/ffmpeg_glue.h"
 
@@ skipping 19 matching lines @@
   // channels(), duration(), and number_of_frames() methods can be called.
   // It returns |true| on success.
   bool Open();
   void Close();
 
   // After a call to Open(), attempts to fully fill |audio_bus| with decoded
   // audio data.  Any unfilled frames will be zeroed out.
   // |audio_data| must be of the same size as channels().
   // The audio data will be decoded as floating-point linear PCM with
   // a nominal range of -1.0 -> +1.0.
-  // Returns |true| on success.
-  bool Read(AudioBus* audio_bus);
+  // Returns the number of sample-frames actually read which will always be
+  // <= audio_bus->frames()
+  // This corresponds to the actual file length.

[DaleCurtis, 2012/10/13 01:10:35]

I'd remove this sentence since it's not correct as the file may be longer.

+  int Read(AudioBus* audio_bus);
 
   // These methods can be called once Open() has been called.
   int channels() const;
   int sample_rate() const;
+
+  // Please note that duration() and number_of_frames() attempt to be accurate,
+  // but are only estimates.  For some encoded formats, the actual duration
+  // of the file can only be determined once all the file data has been read.
+  // The Read() method returns the actual number of sample-frames.
   base::TimeDelta duration() const;
   int64 number_of_frames() const;
 
  private:
   FFmpegURLProtocol* protocol_;
   AVFormatContext* format_context_;
   AVCodecContext* codec_context_;
   int stream_index_;
 
   DISALLOW_COPY_AND_ASSIGN(AudioFileReader);
 };
 
 }  // namespace media
 
 #endif  // MEDIA_FILTERS_AUDIO_FILE_READER_H_