audio_block_fifo.h revision 5f1c94371a64b3196d4be9466099bb892df9b88e 
1// Copyright 2014 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_BLOCK_FIFO_H_
6#define MEDIA_BASE_AUDIO_BLOCK_FIFO_H_
7
8#include "base/memory/scoped_vector.h"
9#include "media/base/audio_bus.h"
10#include "media/base/media_export.h"
11
12namespace media {
13
14// First-in first-out container for AudioBus elements.
15// The FIFO is composed of blocks of AudioBus elements, it accepts interleaved
16// data as input and will deinterleave it into the FIFO, and it only allows
17// consuming a whole block of AudioBus element.
18// This class is thread-unsafe.
19class MEDIA_EXPORT AudioBlockFifo {
20 public:
21  // Creates a new AudioBlockFifo and allocates |blocks| memory, each block
22  // of memory can store |channels| of length |frames| data.
23  AudioBlockFifo(int channels, int frames, int blocks);
24  virtual ~AudioBlockFifo();
25
26  // Pushes interleaved audio data from |source| to the FIFO.
27  // The method will deinterleave the data into a audio bus.
28  // Push() will crash if the allocated space is insufficient.
29  void Push(const void* source, int frames, int bytes_per_sample);
30
31  // Consumes a block of audio from the FIFO.  Returns an AudioBus which
32  // contains the consumed audio data to avoid copying.
33  // Consume() will crash if the FIFO does not contain a block of data.
34  const AudioBus* Consume();
35
36  // Empties the FIFO without deallocating any memory.
37  void Clear();
38
39  // Number of available block of memory ready to be consumed in the FIFO.
40  int available_blocks() const { return available_blocks_; }
41
42  // Number of available frames of data in the FIFO.
43  int GetAvailableFrames() const;
44
45  // Number of unfilled frames in the whole FIFO.
46  int GetUnfilledFrames() const;
47
48 private:
49  // The actual FIFO is a vector of audio buses.
50  ScopedVector<AudioBus> audio_blocks_;
51
52  // Maximum number of frames of data one block of memory can contain.
53  // This value is set by |frames| in the constructor.
54  const int block_frames_;
55
56  // Used to keep track which block of memory to be written.
57  int write_block_;
58
59  // Used to keep track which block of memory to be consumed.
60  int read_block_;
61
62  // Number of available blocks of memory to be consumed.
63  int available_blocks_;
64
65  // Current write position in the current written block.
66  int write_pos_;
67
68  DISALLOW_COPY_AND_ASSIGN(AudioBlockFifo);
69};
70
71}  // namespace media
72
73#endif  // MEDIA_BASE_AUDIO_BLOCK_FIFO_H_
74