media/base/audio_block_fifo.h

   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
  12 namespace 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.
  19 class 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   // Dynamically increase |blocks| of memory to the FIFO.
  49   void IncreaseCapacity(int blocks);
  50
  51  private:
  52   // The actual FIFO is a vector of audio buses.
  53   ScopedVector<AudioBus> audio_blocks_;
  54
  55   // Number of channels in AudioBus.
  56   const int channels_;
  57
  58   // Maximum number of frames of data one block of memory can contain.
  59   // This value is set by |frames| in the constructor.
  60   const int block_frames_;
  61
  62   // Used to keep track which block of memory to be written.
  63   int write_block_;
  64
  65   // Used to keep track which block of memory to be consumed.
  66   int read_block_;
  67
  68   // Number of available blocks of memory to be consumed.
  69   int available_blocks_;
  70
  71   // Current write position in the current written block.
  72   int write_pos_;
  73
  74   DISALLOW_COPY_AND_ASSIGN(AudioBlockFifo);
  75 };
  76
  77 }  // namespace media
  78
  79 #endif  // MEDIA_BASE_AUDIO_BLOCK_FIFO_H_