content/renderer/media/renderer_webaudiodevice_impl.cc

// 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 "content/renderer/media/renderer_webaudiodevice_impl.h"

#include "base/command_line.h"
#include "base/logging.h"
#include "base/single_thread_task_runner.h"
#include "base/thread_task_runner_handle.h"
#include "base/time/time.h"
#include "content/renderer/media/audio_device_factory.h"
#include "content/renderer/render_frame_impl.h"
#include "media/audio/audio_output_device.h"
#include "media/audio/null_audio_sink.h"
#include "media/base/media_switches.h"
#include "third_party/WebKit/public/web/WebLocalFrame.h"
#include "third_party/WebKit/public/web/WebView.h"

using blink::WebAudioDevice;
using blink::WebLocalFrame;
using blink::WebVector;
using blink::WebView;

namespace content {

#if defined(OS_ANDROID)
static const int kSilenceInSecondsToEnterIdleMode = 30;
#endif

RendererWebAudioDeviceImpl::RendererWebAudioDeviceImpl(
    const media::AudioParameters& params,
    WebAudioDevice::RenderCallback* callback,
    int session_id)
    : params_(params),
      client_callback_(callback),
      session_id_(session_id),
      task_runner_(base::ThreadTaskRunnerHandle::Get()),
      null_audio_sink_(new media::NullAudioSink(task_runner_)),
      is_using_null_audio_sink_(false),
      first_buffer_after_silence_(media::AudioBus::Create(params_)),
      is_first_buffer_after_silence_(false) {
  DCHECK(client_callback_);
  null_audio_sink_->Initialize(params_, this);
}

RendererWebAudioDeviceImpl::~RendererWebAudioDeviceImpl() {
  DCHECK(!output_device_);
}

void RendererWebAudioDeviceImpl::start() {
  DCHECK(thread_checker_.CalledOnValidThread());

  if (output_device_)
    return;  // Already started.

  // Assumption: This method is being invoked within a V8 call stack.  CHECKs
  // will fail in the call to frameForCurrentContext() otherwise.
  //
  // Therefore, we can perform look-ups to determine which RenderView is
  // starting the audio device.  The reason for all this is because the creator
  // of the WebAudio objects might not be the actual source of the audio (e.g.,
  // an extension creates a object that is passed and used within a page).
  WebLocalFrame* const web_frame = WebLocalFrame::frameForCurrentContext();
  RenderFrame* const render_frame =
      web_frame ? RenderFrame::FromWebFrame(web_frame) : NULL;
  output_device_ = AudioDeviceFactory::NewOutputDevice(
      render_frame ? render_frame->GetRoutingID(): MSG_ROUTING_NONE);
  output_device_->InitializeWithSessionId(params_, this, session_id_);
  output_device_->Start();
  start_null_audio_sink_callback_.Reset(
      base::Bind(&media::NullAudioSink::Play, null_audio_sink_));
  // Note: Default behavior is to auto-play on start.
}

void RendererWebAudioDeviceImpl::stop() {
  DCHECK(thread_checker_.CalledOnValidThread());

  if (output_device_) {
    output_device_->Stop();
    output_device_ = NULL;
  }
  null_audio_sink_->Stop();
  is_using_null_audio_sink_ = false;
  is_first_buffer_after_silence_ = false;
  start_null_audio_sink_callback_.Cancel();
}

double RendererWebAudioDeviceImpl::sampleRate() {
  return params_.sample_rate();
}

int RendererWebAudioDeviceImpl::Render(media::AudioBus* dest,
                                       int audio_delay_milliseconds) {
#if defined(OS_ANDROID)
  if (is_first_buffer_after_silence_) {
    DCHECK(!is_using_null_audio_sink_);
    first_buffer_after_silence_->CopyTo(dest);
    is_first_buffer_after_silence_ = false;
    return dest->frames();
  }
#endif
  // Wrap the output pointers using WebVector.
  WebVector<float*> web_audio_dest_data(
      static_cast<size_t>(dest->channels()));
  for (int i = 0; i < dest->channels(); ++i)
    web_audio_dest_data[i] = dest->channel(i);

  // TODO(xians): Remove the following |web_audio_source_data| after
  // changing the blink interface.
  WebVector<float*> web_audio_source_data(static_cast<size_t>(0));
  client_callback_->render(web_audio_source_data,
                           web_audio_dest_data,
                           dest->frames());

#if defined(OS_ANDROID)
  const bool is_zero = dest->AreFramesZero();
  if (!is_zero) {
    first_silence_time_ = base::TimeTicks();
    if (is_using_null_audio_sink_) {
      // This is called on the main render thread when audio is detected.
      output_device_->Play();
      is_using_null_audio_sink_ = false;
      is_first_buffer_after_silence_ = true;
      dest->CopyTo(first_buffer_after_silence_.get());
      task_runner_->PostTask(
          FROM_HERE,
          base::Bind(&media::NullAudioSink::Stop, null_audio_sink_));
    }
  } else if (!is_using_null_audio_sink_) {
    // Called on the audio device thread.
    const base::TimeTicks now = base::TimeTicks::Now();
    if (first_silence_time_.is_null())
      first_silence_time_ = now;
    if (now - first_silence_time_
        > base::TimeDelta::FromSeconds(kSilenceInSecondsToEnterIdleMode)) {
      output_device_->Pause();
      is_using_null_audio_sink_ = true;
      // If Stop() is called right after the task is posted, need to cancel
      // this task.
      task_runner_->PostDelayedTask(
          FROM_HERE,
          start_null_audio_sink_callback_.callback(),
          params_.GetBufferDuration());
    }
  }
#endif
  return dest->frames();
}

void RendererWebAudioDeviceImpl::OnRenderError() {
  // TODO(crogers): implement error handling.
}

}  // namespace content