| // 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; |
| } |
| } |