media/base/audio_splicer.h

   1 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #ifndef MEDIA_BASE_AUDIO_SPLICER_H_
   6 #define MEDIA_BASE_AUDIO_SPLICER_H_
   7
   8 #include <deque>
   9
  10 #include "base/memory/ref_counted.h"
  11 #include "media/base/audio_timestamp_helper.h"
  12 #include "media/base/media_export.h"
  13
  14 namespace media {
  15
  16 class AudioBuffer;
  17 class AudioDecoderConfig;
  18
  19 // Helper class that handles filling gaps and resolving overlaps.
  20 class MEDIA_EXPORT AudioSplicer {
  21  public:
  22   AudioSplicer(int samples_per_second);
  23   ~AudioSplicer();
  24
  25   // Resets the splicer state by clearing the output buffers queue,
  26   // and resetting the timestamp helper.
  27   void Reset();
  28
  29   // Adds a new buffer full of samples or end of stream buffer to the splicer.
  30   // Returns true if the buffer was accepted. False is returned if an error
  31   // occurred.
  32   bool AddInput(const scoped_refptr<AudioBuffer>& input);
  33
  34   // Returns true if the splicer has a buffer to return.
  35   bool HasNextBuffer() const;
  36
  37   // Removes the next buffer from the output buffer queue and returns it.
  38   // This should only be called if HasNextBuffer() returns true.
  39   scoped_refptr<AudioBuffer> GetNextBuffer();
  40
  41  private:
  42   void AddOutputBuffer(const scoped_refptr<AudioBuffer>& buffer);
  43
  44   AudioTimestampHelper output_timestamp_helper_;
  45
  46   // Minimum gap size needed before the splicer will take action to
  47   // fill a gap. This avoids periodically inserting and then dropping samples
  48   // when the buffer timestamps are slightly off because of timestamp rounding
  49   // in the source content. Unit is frames.
  50   int min_gap_size_;
  51
  52   std::deque<scoped_refptr<AudioBuffer> > output_buffers_;
  53   bool received_end_of_stream_;
  54
  55   DISALLOW_IMPLICIT_CONSTRUCTORS(AudioSplicer);
  56 };
  57
  58 }  // namespace media
  59
  60 #endif