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      1 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
      2 // Use of this source code is governed by a BSD-style license that can be
      3 // found in the LICENSE file.
      4 
      5 #include "content/renderer/media/renderer_webaudiodevice_impl.h"
      6 
      7 #include "base/command_line.h"
      8 #include "base/logging.h"
      9 #include "content/renderer/media/audio_device_factory.h"
     10 #include "content/renderer/render_view_impl.h"
     11 #include "media/audio/audio_output_device.h"
     12 #include "media/base/media_switches.h"
     13 #include "third_party/WebKit/public/web/WebFrame.h"
     14 #include "third_party/WebKit/public/web/WebView.h"
     15 
     16 using blink::WebAudioDevice;
     17 using blink::WebFrame;
     18 using blink::WebVector;
     19 using blink::WebView;
     20 
     21 namespace content {
     22 
     23 RendererWebAudioDeviceImpl::RendererWebAudioDeviceImpl(
     24     const media::AudioParameters& params,
     25     WebAudioDevice::RenderCallback* callback,
     26     int session_id)
     27     : params_(params),
     28       client_callback_(callback),
     29       session_id_(session_id) {
     30   DCHECK(client_callback_);
     31 }
     32 
     33 RendererWebAudioDeviceImpl::~RendererWebAudioDeviceImpl() {
     34   DCHECK(!output_device_.get());
     35 }
     36 
     37 void RendererWebAudioDeviceImpl::start() {
     38   DCHECK(thread_checker_.CalledOnValidThread());
     39 
     40   if (output_device_.get())
     41     return;  // Already started.
     42 
     43   // Assumption: This method is being invoked within a V8 call stack.  CHECKs
     44   // will fail in the call to frameForCurrentContext() otherwise.
     45   //
     46   // Therefore, we can perform look-ups to determine which RenderView is
     47   // starting the audio device.  The reason for all this is because the creator
     48   // of the WebAudio objects might not be the actual source of the audio (e.g.,
     49   // an extension creates a object that is passed and used within a page).
     50   WebFrame* const web_frame = WebFrame::frameForCurrentContext();
     51   WebView* const web_view = web_frame ? web_frame->view() : NULL;
     52   RenderViewImpl* const render_view =
     53       web_view ? RenderViewImpl::FromWebView(web_view) : NULL;
     54   output_device_ = AudioDeviceFactory::NewOutputDevice(
     55       render_view ? render_view->routing_id() : MSG_ROUTING_NONE);
     56   output_device_->InitializeUnifiedStream(params_, this, session_id_);
     57   output_device_->Start();
     58   // Note: Default behavior is to auto-play on start.
     59 }
     60 
     61 void RendererWebAudioDeviceImpl::stop() {
     62   DCHECK(thread_checker_.CalledOnValidThread());
     63 
     64   if (output_device_.get()) {
     65     output_device_->Stop();
     66     output_device_ = NULL;
     67   }
     68 }
     69 
     70 double RendererWebAudioDeviceImpl::sampleRate() {
     71   return params_.sample_rate();
     72 }
     73 
     74 int RendererWebAudioDeviceImpl::Render(media::AudioBus* dest,
     75                                        int audio_delay_milliseconds) {
     76   RenderIO(NULL, dest, audio_delay_milliseconds);
     77   return dest->frames();
     78 }
     79 
     80 void RendererWebAudioDeviceImpl::RenderIO(media::AudioBus* source,
     81                                           media::AudioBus* dest,
     82                                           int audio_delay_milliseconds) {
     83   // Make the client callback for an I/O cycle.
     84   if (client_callback_) {
     85     // Wrap the input pointers using WebVector.
     86     size_t source_channels =
     87         source ? static_cast<size_t>(source->channels()) : 0;
     88     WebVector<float*> web_audio_source_data(source_channels);
     89     for (size_t i = 0; i < source_channels; ++i)
     90       web_audio_source_data[i] = source->channel(i);
     91 
     92     // Wrap the output pointers using WebVector.
     93     WebVector<float*> web_audio_dest_data(
     94         static_cast<size_t>(dest->channels()));
     95     for (int i = 0; i < dest->channels(); ++i)
     96       web_audio_dest_data[i] = dest->channel(i);
     97 
     98     client_callback_->render(web_audio_source_data,
     99                              web_audio_dest_data,
    100                              dest->frames());
    101   }
    102 }
    103 
    104 void RendererWebAudioDeviceImpl::OnRenderError() {
    105   // TODO(crogers): implement error handling.
    106 }
    107 
    108 }  // namespace content
    109