// Copyright (c) 2013 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/fake_audio_consumer.h"
#include "base/bind.h"
#include "base/bind_helpers.h"
#include "base/cancelable_callback.h"
#include "base/logging.h"
#include "base/memory/scoped_ptr.h"
#include "base/message_loop/message_loop.h"
#include "base/message_loop/message_loop_proxy.h"
#include "base/synchronization/lock.h"
#include "base/threading/thread_checker.h"
#include "base/time/time.h"
#include "media/audio/audio_parameters.h"
#include "media/base/audio_bus.h"
namespace media {
class FakeAudioConsumer::Worker
: public base::RefCountedThreadSafe<FakeAudioConsumer::Worker> {
public:
Worker(const scoped_refptr<base::MessageLoopProxy>& worker_loop,
const AudioParameters& params);
bool IsStopped();
void Start(const ReadCB& read_cb);
void Stop();
private:
friend class base::RefCountedThreadSafe<Worker>;
~Worker();
// Initialize and start regular calls to DoRead() on the worker thread.
void DoStart();
// Cancel any delayed callbacks to DoRead() in the worker loop's queue.
void DoCancel();
// Task that regularly calls |read_cb_| according to the playback rate as
// determined by the audio parameters given during construction. Runs on
// the worker loop.
void DoRead();
const scoped_refptr<base::MessageLoopProxy> worker_loop_;
const scoped_ptr<AudioBus> audio_bus_;
const base::TimeDelta buffer_duration_;
base::Lock read_cb_lock_; // Held while mutating or running |read_cb_|.
ReadCB read_cb_;
base::TimeTicks next_read_time_;
// Used to cancel any delayed tasks still inside the worker loop's queue.
base::CancelableClosure read_task_cb_;
base::ThreadChecker thread_checker_;
DISALLOW_COPY_AND_ASSIGN(Worker);
};
FakeAudioConsumer::FakeAudioConsumer(
const scoped_refptr<base::MessageLoopProxy>& worker_loop,
const AudioParameters& params)
: worker_(new Worker(worker_loop, params)) {
}
FakeAudioConsumer::~FakeAudioConsumer() {
DCHECK(worker_->IsStopped());
}
void FakeAudioConsumer::Start(const ReadCB& read_cb) {
DCHECK(worker_->IsStopped());
worker_->Start(read_cb);
}
void FakeAudioConsumer::Stop() {
worker_->Stop();
}
FakeAudioConsumer::Worker::Worker(
const scoped_refptr<base::MessageLoopProxy>& worker_loop,
const AudioParameters& params)
: worker_loop_(worker_loop),
audio_bus_(AudioBus::Create(params)),
buffer_duration_(base::TimeDelta::FromMicroseconds(
params.frames_per_buffer() * base::Time::kMicrosecondsPerSecond /
static_cast<float>(params.sample_rate()))) {
audio_bus_->Zero();
// Worker can be constructed on any thread, but will DCHECK that its
// Start/Stop methods are called from the same thread.
thread_checker_.DetachFromThread();
}
FakeAudioConsumer::Worker::~Worker() {
DCHECK(read_cb_.is_null());
}
bool FakeAudioConsumer::Worker::IsStopped() {
base::AutoLock scoped_lock(read_cb_lock_);
return read_cb_.is_null();
}
void FakeAudioConsumer::Worker::Start(const ReadCB& read_cb) {
DCHECK(thread_checker_.CalledOnValidThread());
DCHECK(!read_cb.is_null());
{
base::AutoLock scoped_lock(read_cb_lock_);
DCHECK(read_cb_.is_null());
read_cb_ = read_cb;
}
worker_loop_->PostTask(FROM_HERE, base::Bind(&Worker::DoStart, this));
}
void FakeAudioConsumer::Worker::DoStart() {
DCHECK(worker_loop_->BelongsToCurrentThread());
next_read_time_ = base::TimeTicks::Now();
read_task_cb_.Reset(base::Bind(&Worker::DoRead, this));
read_task_cb_.callback().Run();
}
void FakeAudioConsumer::Worker::Stop() {
DCHECK(thread_checker_.CalledOnValidThread());
{
base::AutoLock scoped_lock(read_cb_lock_);
if (read_cb_.is_null())
return;
read_cb_.Reset();
}
worker_loop_->PostTask(FROM_HERE, base::Bind(&Worker::DoCancel, this));
}
void FakeAudioConsumer::Worker::DoCancel() {
DCHECK(worker_loop_->BelongsToCurrentThread());
read_task_cb_.Cancel();
}
void FakeAudioConsumer::Worker::DoRead() {
DCHECK(worker_loop_->BelongsToCurrentThread());
{
base::AutoLock scoped_lock(read_cb_lock_);
if (!read_cb_.is_null())
read_cb_.Run(audio_bus_.get());
}
// Need to account for time spent here due to the cost of |read_cb_| as well
// as the imprecision of PostDelayedTask().
const base::TimeTicks now = base::TimeTicks::Now();
base::TimeDelta delay = next_read_time_ + buffer_duration_ - now;
// If we're behind, find the next nearest ontime interval.
if (delay < base::TimeDelta())
delay += buffer_duration_ * (-delay / buffer_duration_ + 1);
next_read_time_ = now + delay;
worker_loop_->PostDelayedTask(FROM_HERE, read_task_cb_.callback(), delay);
}
} // namespace media