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 #include "media/base/audio_pull_fifo.h" 6 7 #include <algorithm> 8 9 #include "base/logging.h" 10 #include "media/base/audio_bus.h" 11 12 namespace media { 13 14 AudioPullFifo::AudioPullFifo(int channels, int frames, const ReadCB& read_cb) 15 : read_cb_(read_cb), 16 fifo_(AudioBus::Create(channels, frames)), 17 fifo_index_(frames) {} 18 19 AudioPullFifo::~AudioPullFifo() {} 20 21 void AudioPullFifo::Consume(AudioBus* destination, int frames_to_consume) { 22 DCHECK_LE(frames_to_consume, destination->frames()); 23 24 int remaining_frames_to_provide = frames_to_consume; 25 26 // Try to fulfill the request using what's available in the FIFO. 27 int frames_read = ReadFromFifo(destination, remaining_frames_to_provide, 0); 28 int write_pos = frames_read; 29 remaining_frames_to_provide -= frames_read; 30 31 // Get the remaining audio frames from the producer using the callback. 32 while (remaining_frames_to_provide > 0) { 33 DCHECK_EQ(fifo_index_, fifo_->frames()); 34 fifo_index_ = 0; 35 36 // Fill up the FIFO by acquiring audio data from the producer. 37 read_cb_.Run(write_pos, fifo_.get()); 38 39 // Try to fulfill the request using what's available in the FIFO. 40 frames_read = 41 ReadFromFifo(destination, remaining_frames_to_provide, write_pos); 42 write_pos += frames_read; 43 remaining_frames_to_provide -= frames_read; 44 } 45 } 46 47 void AudioPullFifo::Clear() { fifo_index_ = fifo_->frames(); } 48 49 int AudioPullFifo::ReadFromFifo(AudioBus* destination, 50 int frames_to_provide, 51 int write_pos) { 52 int frames = std::min(frames_to_provide, fifo_->frames() - fifo_index_); 53 if (frames <= 0) 54 return 0; 55 56 for (int ch = 0; ch < fifo_->channels(); ++ch) { 57 const float* src = fifo_->channel(ch) + fifo_index_; 58 float* dest = destination->channel(ch) + write_pos; 59 memcpy(dest, src, frames * sizeof(*src)); 60 } 61 62 fifo_index_ += frames; 63 return frames; 64 } 65 66 } // namespace media 67
