content/renderer/media/webaudio_capturer_source.h

   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 #ifndef CONTENT_RENDERER_MEDIA_WEBAUDIO_CAPTURER_SOURCE_H_
   6 #define CONTENT_RENDERER_MEDIA_WEBAUDIO_CAPTURER_SOURCE_H_
   7
   8 #include "base/memory/ref_counted.h"
   9 #include "base/synchronization/lock.h"
  10 #include "base/threading/thread_checker.h"
  11 #include "media/audio/audio_parameters.h"
  12 #include "media/base/audio_capturer_source.h"
  13 #include "media/base/audio_fifo.h"
  14 #include "third_party/WebKit/public/platform/WebAudioDestinationConsumer.h"
  15 #include "third_party/WebKit/public/platform/WebMediaStreamSource.h"
  16 #include "third_party/WebKit/public/platform/WebVector.h"
  17
  18 namespace content {
  19
  20 class WebRtcLocalAudioTrack;
  21
  22 // WebAudioCapturerSource is the missing link between
  23 // WebAudio's MediaStreamAudioDestinationNode and WebRtcLocalAudioTrack.
  24 //
  25 // 1. WebKit calls the setFormat() method setting up the basic stream format
  26 //    (channels, and sample-rate).
  27 // 2. consumeAudio() is called periodically by WebKit which dispatches the
  28 //    audio stream to the WebRtcLocalAudioTrack::Capture() method.
  29 class WebAudioCapturerSource
  30     :  public base::RefCountedThreadSafe<WebAudioCapturerSource>,
  31        public blink::WebAudioDestinationConsumer {
  32  public:
  33   explicit WebAudioCapturerSource(
  34       const blink::WebMediaStreamSource& blink_source);
  35
  36   // WebAudioDestinationConsumer implementation.
  37   // setFormat() is called early on, so that we can configure the audio track.
  38   void setFormat(size_t number_of_channels, float sample_rate) override;
  39   // MediaStreamAudioDestinationNode periodically calls consumeAudio().
  40   // Called on the WebAudio audio thread.
  41   void consumeAudio(const blink::WebVector<const float*>& audio_data,
  42                     size_t number_of_frames) override;
  43
  44   // Called when the WebAudioCapturerSource is hooking to a media audio track.
  45   // |track| is the sink of the data flow. |source_provider| is the source of
  46   // the data flow where stream information like delay, volume, key_pressed,
  47   // is stored.
  48   void Start(WebRtcLocalAudioTrack* track);
  49
  50   // Called when the media audio track is stopping.
  51   void Stop();
  52
  53  protected:
  54   friend class base::RefCountedThreadSafe<WebAudioCapturerSource>;
  55   ~WebAudioCapturerSource() override;
  56
  57  private:
  58   // Removes this object from a blink::WebMediaStreamSource with which it
  59   // might be registered. The goal is to avoid dangling pointers.
  60   void removeFromBlinkSource();
  61
  62   // Used to DCHECK that some methods are called on the correct thread.
  63   base::ThreadChecker thread_checker_;
  64
  65   // The audio track this WebAudioCapturerSource is feeding data to.
  66   // WebRtcLocalAudioTrack is reference counted, and owning this object.
  67   // To avoid circular reference, a raw pointer is kept here.
  68   WebRtcLocalAudioTrack* track_;
  69
  70   media::AudioParameters params_;
  71
  72   // Flag to help notify the |track_| when the audio format has changed.
  73   bool audio_format_changed_;
  74
  75   // Wraps data coming from HandleCapture().
  76   scoped_ptr<media::AudioBus> wrapper_bus_;
  77
  78   // Bus for reading from FIFO and calling the CaptureCallback.
  79   scoped_ptr<media::AudioBus> capture_bus_;
  80
  81   // Handles mismatch between WebAudio buffer size and WebRTC.
  82   scoped_ptr<media::AudioFifo> fifo_;
  83
  84   // Synchronizes HandleCapture() with AudioCapturerSource calls.
  85   base::Lock lock_;
  86   bool started_;
  87
  88   // This object registers with a blink::WebMediaStreamSource. We keep track of
  89   // that in order to be able to deregister before stopping the audio track.
  90   blink::WebMediaStreamSource blink_source_;
  91
  92   DISALLOW_COPY_AND_ASSIGN(WebAudioCapturerSource);
  93 };
  94
  95 }  // namespace content
  96
  97 #endif  // CONTENT_RENDERER_MEDIA_WEBAUDIO_CAPTURER_SOURCE_H_