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// Copyright (c) 2012 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include "media/base/audio_pull_fifo.h"
#include <algorithm>
#include "base/logging.h"
#include "media/base/audio_bus.h"
namespace media {
AudioPullFifo::AudioPullFifo(int channels, int frames, const ReadCB& read_cb)
: read_cb_(read_cb),
fifo_(AudioBus::Create(channels, frames)),
fifo_index_(frames) {}
AudioPullFifo::~AudioPullFifo() {}
void AudioPullFifo::Consume(AudioBus* destination, int frames_to_consume) {
DCHECK_LE(frames_to_consume, destination->frames());
int remaining_frames_to_provide = frames_to_consume;
// Try to fulfill the request using what's available in the FIFO.
int frames_read = ReadFromFifo(destination, remaining_frames_to_provide, 0);
int write_pos = frames_read;
remaining_frames_to_provide -= frames_read;
// Get the remaining audio frames from the producer using the callback.
while (remaining_frames_to_provide > 0) {
DCHECK_EQ(fifo_index_, fifo_->frames());
fifo_index_ = 0;
// Fill up the FIFO by acquiring audio data from the producer.
read_cb_.Run(write_pos, fifo_.get());
// Try to fulfill the request using what's available in the FIFO.
frames_read =
ReadFromFifo(destination, remaining_frames_to_provide, write_pos);
write_pos += frames_read;
remaining_frames_to_provide -= frames_read;
}
}
void AudioPullFifo::Clear() { fifo_index_ = fifo_->frames(); }
int AudioPullFifo::ReadFromFifo(AudioBus* destination,
int frames_to_provide,
int write_pos) {
int frames = std::min(frames_to_provide, fifo_->frames() - fifo_index_);
if (frames <= 0)
return 0;
for (int ch = 0; ch < fifo_->channels(); ++ch) {
const float* src = fifo_->channel(ch) + fifo_index_;
float* dest = destination->channel(ch) + write_pos;
memcpy(dest, src, frames * sizeof(*src));
}
fifo_index_ += frames;
return frames;
}
} // namespace media
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