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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"
namespace media {
AudioPullFifo::AudioPullFifo(int channels, int frames, const ReadCB& read_cb)
: read_cb_(read_cb) {
fifo_.reset(new AudioFifo(channels, frames));
bus_ = AudioBus::Create(channels, frames);
}
AudioPullFifo::~AudioPullFifo() {
read_cb_.Reset();
}
void AudioPullFifo::Consume(AudioBus* destination, int frames_to_consume) {
DCHECK(destination);
DCHECK_LE(frames_to_consume, destination->frames());
int write_pos = 0;
int remaining_frames_to_provide = frames_to_consume;
// Try to fulfill the request using what's available in the FIFO.
ReadFromFifo(destination, &remaining_frames_to_provide, &write_pos);
// Get the remaining audio frames from the producer using the callback.
while (remaining_frames_to_provide > 0) {
// Fill up the FIFO by acquiring audio data from the producer.
read_cb_.Run(write_pos, bus_.get());
fifo_->Push(bus_.get());
// Try to fulfill the request using what's available in the FIFO.
ReadFromFifo(destination, &remaining_frames_to_provide, &write_pos);
}
}
void AudioPullFifo::Clear() {
fifo_->Clear();
}
void AudioPullFifo::ReadFromFifo(AudioBus* destination,
int* frames_to_provide,
int* write_pos) {
DCHECK(frames_to_provide);
DCHECK(write_pos);
int frames = std::min(fifo_->frames(), *frames_to_provide);
fifo_->Consume(destination, *write_pos, frames);
*write_pos += frames;
*frames_to_provide -= frames;
}
} // namespace media
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