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// Copyright 2016 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/virtual_audio_sink.h"
#include "base/bind.h"
#include "base/callback_helpers.h"
#include "base/location.h"
#include "base/single_thread_task_runner.h"
#include "media/audio/virtual_audio_input_stream.h"
namespace media {
// Buffer size limit is chosen large enough that in the normal case, we do not
// have data loss.
constexpr int kBufferSizeSecond = 1;
// The accuracy contains two components: 1. the cross-process communication,
// there is fluctuation between the actual and the ideal instant when we receive
// the audio data; 2. The system clock resolution: worst case is ~15ms on
// Windows machines without a working high-resolution clock.
constexpr int kClockAccuracyMillisecond = 20;
// See AudioShifter comment for detail about this parameter. We just take the
// suggestion from there.
constexpr int kAdjustTimeSecond = 1;
VirtualAudioSink::VirtualAudioSink(const AudioParameters& param,
VirtualAudioInputStream* target,
const AfterCloseCallback& callback)
: params_(param),
target_(target),
shifter_(base::TimeDelta::FromSeconds(kBufferSizeSecond),
base::TimeDelta::FromMilliseconds(kClockAccuracyMillisecond),
base::TimeDelta::FromSeconds(kAdjustTimeSecond),
param.sample_rate(),
param.channels()),
after_close_callback_(callback) {
target_->AddInputProvider(this, params_);
}
VirtualAudioSink::~VirtualAudioSink() {}
void VirtualAudioSink::Close() {
target_->RemoveInputProvider(this, params_);
const AfterCloseCallback& cb = base::ResetAndReturn(&after_close_callback_);
if (!cb.is_null())
cb.Run(this);
}
void VirtualAudioSink::OnData(std::unique_ptr<AudioBus> source,
base::TimeTicks reference_time) {
base::AutoLock lock(shifter_lock_);
shifter_.Push(std::move(source), reference_time);
}
double VirtualAudioSink::ProvideInput(AudioBus* audio_bus,
uint32_t frames_delayed) {
base::AutoLock lock(shifter_lock_);
shifter_.Pull(audio_bus,
base::TimeTicks::Now() +
base::TimeDelta::FromMicroseconds(
frames_delayed * params_.GetMicrosecondsPerFrame()));
return 1;
}
}
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