Enhance AudioSplicer to crossfade marked splice frames.

media/base/audio_timestamp_helper.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_BASE_AUDIO_TIMESTAMP_HELPER_H_
 #define MEDIA_BASE_AUDIO_TIMESTAMP_HELPER_H_
 
 #include "base/time/time.h"
 #include "media/base/media_export.h"
 
 namespace media {
 
 // Generates timestamps for a sequence of audio sample frames. This class should
 // be used any place timestamps need to be calculated for a sequence of audio
 // samples. It helps avoid timestamps inaccuracies caused by rounding/truncation
 // in repeated sample count to timestamp conversions.
 //
 // The class is constructed with samples_per_second information so that it can
 // convert audio sample frame counts into timestamps. After the object is
 // constructed, SetBaseTimestamp() must be called to specify the starting
 // timestamp of the audio sequence. As audio samples are received, their frame
 // counts are added using AddFrames(). These frame counts are accumulated by
 // this class so GetTimestamp() can be used to determine the timestamp for the
 // samples that have been added. GetDuration() calculates the proper duration
 // values for samples added to the current timestamp. GetFramesToTarget()
 // determines the number of frames that need to be added/removed from the
 // accumulated frames to reach a target timestamp.
 class MEDIA_EXPORT AudioTimestampHelper {
  public:
-  AudioTimestampHelper(int samples_per_second);
+  explicit AudioTimestampHelper(int samples_per_second);
 
   // Sets the base timestamp to |base_timestamp| and the sets count to 0.
   void SetBaseTimestamp(base::TimeDelta base_timestamp);
 
   base::TimeDelta base_timestamp() const;
+  int64 frame_count() const { return frame_count_; }
 
   // Adds |frame_count| to the frame counter.
   // Note: SetBaseTimestamp() must be called with a value other than
   // kNoTimestamp() before this method can be called.
   void AddFrames(int frame_count);
 
   // Get the current timestamp. This value is computed from the base_timestamp()
   // and the number of sample frames that have been added so far.
   base::TimeDelta GetTimestamp() const;
 
@@ skipping 16 matching lines @@
 
   // Number of frames accumulated by AddFrames() calls.
   int64 frame_count_;
 
   DISALLOW_IMPLICIT_CONSTRUCTORS(AudioTimestampHelper);
 };
 
 }  // namespace media
 
 #endif