src/media/base/audio_block_fifo.cc

   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 #include "media/base/audio_block_fifo.h"
   6
   7 #include "base/logging.h"
   8
   9 namespace media {
  10
  11 AudioBlockFifo::AudioBlockFifo(int channels, int frames, int blocks)
  12     : block_frames_(frames),
  13       write_block_(0),
  14       read_block_(0),
  15       available_blocks_(0),
  16       write_pos_(0) {
  17   // Create |blocks| of audio buses and push them to the containers.
  18   audio_blocks_.reserve(blocks);
  19   for (int i = 0; i < blocks; ++i) {
  20     scoped_ptr<AudioBus> audio_bus = AudioBus::Create(channels, frames);
  21     audio_blocks_.push_back(audio_bus.release());
  22   }
  23 }
  24
  25 AudioBlockFifo::~AudioBlockFifo() {}
  26
  27 void AudioBlockFifo::Push(const void* source,
  28                           int frames,
  29                           int bytes_per_sample) {
  30   DCHECK(source);
  31   DCHECK_GT(frames, 0);
  32   DCHECK_GT(bytes_per_sample, 0);
  33   DCHECK_LT(available_blocks_, static_cast<int>(audio_blocks_.size()));
  34
  35   const uint8* source_ptr = static_cast<const uint8*>(source);
  36   int frames_to_push = frames;
  37   while (frames_to_push) {
  38     // Get the current write block.
  39     AudioBus* current_block = audio_blocks_[write_block_];
  40
  41     // Figure out what segment sizes we need when adding the new content to
  42     // the FIFO.
  43     const int push_frames =
  44         std::min(block_frames_ - write_pos_, frames_to_push);
  45
  46     // Deinterleave the content to the FIFO and update the |write_pos_|.
  47     current_block->FromInterleavedPartial(
  48         source_ptr, write_pos_, push_frames, bytes_per_sample);
  49     write_pos_ = (write_pos_ + push_frames) % block_frames_;
  50     if (!write_pos_) {
  51       // The current block is completely filled, increment |write_block_| and
  52       // |available_blocks_|.
  53       write_block_ = (write_block_ + 1) % audio_blocks_.size();
  54       ++available_blocks_;
  55     }
  56
  57     source_ptr += push_frames * bytes_per_sample * current_block->channels();
  58     frames_to_push -= push_frames;
  59     DCHECK_GE(frames_to_push, 0);
  60   }
  61 }
  62
  63 const AudioBus* AudioBlockFifo::Consume() {
  64   DCHECK(available_blocks_);
  65   AudioBus* audio_bus = audio_blocks_[read_block_];
  66   read_block_ = (read_block_ + 1) % audio_blocks_.size();
  67   --available_blocks_;
  68   return audio_bus;
  69 }
  70
  71 void AudioBlockFifo::Clear() {
  72   write_pos_ = 0;
  73   write_block_ = 0;
  74   read_block_ = 0;
  75   available_blocks_ = 0;
  76 }
  77
  78 int AudioBlockFifo::GetAvailableFrames() const {
  79   return available_blocks_ * block_frames_ + write_pos_;
  80 }
  81
  82 int AudioBlockFifo::GetUnfilledFrames() const {
  83   const int unfilled_frames =
  84       (audio_blocks_.size() - available_blocks_) * block_frames_ - write_pos_;
  85   DCHECK_GE(unfilled_frames, 0);
  86   return unfilled_frames;
  87 }
  88
  89 }  // namespace media