Express audio delay more precisely in frames rather than milliseconds.

media/audio/audio_parameters.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_AUDIO_AUDIO_PARAMETERS_H_
 #define MEDIA_AUDIO_AUDIO_PARAMETERS_H_
 
 #include <stdint.h>
 #include <string>
 
@@ skipping 107 matching lines @@
 
   // Returns size of audio buffer in bytes.
   int GetBytesPerBuffer() const;
 
   // Returns the number of bytes representing one second of audio.
   int GetBytesPerSecond() const;
 
   // Returns the number of bytes representing a frame of audio.
   int GetBytesPerFrame() const;
 
+  // Returns the number of microseconds per frame of audio. Intentionally
+  // reported as a double to surface of partial microseconds per frame, which
+  // is common for many sample rates. Failing to account for these nanoseconds
+  // can lead to audio/video sync drift.
+  double GetMicrosecondsPerFrame() const;
+
   // Returns the duration of this buffer as calculated from frames_per_buffer()
   // and sample_rate().
   base::TimeDelta GetBufferDuration() const;
 
   // Comparison with other AudioParams.
   bool Equals(const AudioParameters& other) const;
 
   void set_format(Format format) { format_ = format; }
   Format format() const { return format_; }
 
@@ skipping 66 matching lines @@
   if (a.sample_rate() != b.sample_rate())
     return a.sample_rate() < b.sample_rate();
   if (a.bits_per_sample() != b.bits_per_sample())
     return a.bits_per_sample() < b.bits_per_sample();
   return a.frames_per_buffer() < b.frames_per_buffer();
 }
 
 }  // namespace media
 
 #endif  // MEDIA_AUDIO_AUDIO_PARAMETERS_H_