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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/audio/null_audio_sink.h"
#include "base/bind.h"
#include "base/stringprintf.h"
#include "base/sys_byteorder.h"
#include "base/threading/platform_thread.h"
namespace media {
NullAudioSink::NullAudioSink()
: initialized_(false),
playing_(false),
callback_(NULL),
thread_("NullAudioThread"),
hash_audio_for_testing_(false) {
}
void NullAudioSink::Initialize(const AudioParameters& params,
RenderCallback* callback) {
DCHECK(!initialized_);
params_ = params;
audio_bus_ = AudioBus::Create(params_);
if (hash_audio_for_testing_) {
md5_channel_contexts_.reset(new base::MD5Context[params_.channels()]);
for (int i = 0; i < params_.channels(); i++)
base::MD5Init(&md5_channel_contexts_[i]);
}
callback_ = callback;
initialized_ = true;
}
void NullAudioSink::Start() {
if (!thread_.Start())
return;
thread_.message_loop()->PostTask(FROM_HERE, base::Bind(
&NullAudioSink::FillBufferTask, this));
}
void NullAudioSink::Stop() {
SetPlaying(false);
thread_.Stop();
}
void NullAudioSink::Play() {
SetPlaying(true);
}
void NullAudioSink::Pause(bool /* flush */) {
SetPlaying(false);
}
bool NullAudioSink::SetVolume(double volume) {
// Audio is always muted.
return volume == 0.0;
}
void NullAudioSink::SetPlaying(bool is_playing) {
base::AutoLock auto_lock(lock_);
playing_ = is_playing;
}
NullAudioSink::~NullAudioSink() {
DCHECK(!thread_.IsRunning());
}
void NullAudioSink::FillBufferTask() {
base::AutoLock auto_lock(lock_);
base::TimeDelta delay;
// Only consume buffers when actually playing.
if (playing_) {
int frames_received = callback_->Render(audio_bus_.get(), 0);
int frames_per_millisecond =
params_.sample_rate() / base::Time::kMillisecondsPerSecond;
if (hash_audio_for_testing_ && frames_received > 0) {
DCHECK_EQ(sizeof(float), sizeof(uint32));
int channels = audio_bus_->channels();
for (int channel_idx = 0; channel_idx < channels; ++channel_idx) {
float* channel = audio_bus_->channel(channel_idx);
for (int frame_idx = 0; frame_idx < frames_received; frame_idx++) {
// Convert float to uint32 w/o conversion loss.
uint32 frame = base::ByteSwapToLE32(
bit_cast<uint32>(channel[frame_idx]));
base::MD5Update(
&md5_channel_contexts_[channel_idx], base::StringPiece(
reinterpret_cast<char*>(&frame), sizeof(frame)));
}
}
}
// Calculate our sleep duration.
delay = base::TimeDelta::FromMilliseconds(
frames_received / frames_per_millisecond);
} else {
// If paused, sleep for 10 milliseconds before polling again.
delay = base::TimeDelta::FromMilliseconds(10);
}
// Sleep for at least one millisecond so we don't spin the CPU.
MessageLoop::current()->PostDelayedTask(
FROM_HERE,
base::Bind(&NullAudioSink::FillBufferTask, this),
std::max(delay, base::TimeDelta::FromMilliseconds(1)));
}
void NullAudioSink::StartAudioHashForTesting() {
DCHECK(!initialized_);
hash_audio_for_testing_ = true;
}
std::string NullAudioSink::GetAudioHashForTesting() {
DCHECK(hash_audio_for_testing_);
// If initialize failed or was never called, ensure we return an empty hash.
int channels = 1;
if (!initialized_) {
md5_channel_contexts_.reset(new base::MD5Context[1]);
base::MD5Init(&md5_channel_contexts_[0]);
} else {
channels = audio_bus_->channels();
}
// Hash all channels into the first channel.
base::MD5Digest digest;
for (int i = 1; i < channels; i++) {
base::MD5Final(&digest, &md5_channel_contexts_[i]);
base::MD5Update(&md5_channel_contexts_[0], base::StringPiece(
reinterpret_cast<char*>(&digest), sizeof(base::MD5Digest)));
}
base::MD5Final(&digest, &md5_channel_contexts_[0]);
return base::MD5DigestToBase16(digest);
}
} // namespace media
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