MediaStream audio sourcing: Bypass audio processing for non-WebRTC cases.

content/renderer/media/local_media_stream_audio_source.h

+// 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.
+
+#ifndef CONTENT_RENDERER_MEDIA_LOCAL_MEDIA_STREAM_AUDIO_SOURCE_H_
+#define CONTENT_RENDERER_MEDIA_LOCAL_MEDIA_STREAM_AUDIO_SOURCE_H_
+
+#include "content/common/media/media_stream_options.h"
+#include "content/renderer/media/media_stream_audio_source.h"
+#include "media/base/audio_capturer_source.h"
+#include "media/audio/audio_input_device.h"
+
+namespace content {
+
+// Represents a local source of audio data generated by an AudioInputDevice.
+// Uses content::AudioDeviceFactory to auto-create the AudioInputDevice, using
+// the parameters and session ID found in StreamDeviceInfo, just before the
+// first track is connected.  Audio data is transported directly to the tracks
+// (i.e., there is no audio processing).
+class CONTENT_EXPORT LocalMediaStreamAudioSource
+    : NON_EXPORTED_BASE(public MediaStreamAudioSource),
+      NON_EXPORTED_BASE(public media::AudioCapturerSource::CaptureCallback) {
+ public:
+  // |consumer_render_frame_id| references the RenderFrame that will consume the
+  // audio data.  Audio parameters and (optionally) a pre-existing audio session
+  // ID are read from |device_info|.
+  LocalMediaStreamAudioSource(int consumer_render_frame_id,
+                              const StreamDeviceInfo& device_info);
+
+  ~LocalMediaStreamAudioSource() final;
+
+ private:
+  // MediaStreamAudioSource implementation.
+  void DoStopSource() final;
+  bool EnsureSourceIsStarted() final;
+
+  // media::AudioCapturerSource::CaptureCallback implementation.
+  void Capture(const media::AudioBus* audio_bus,
+               int audio_delay_milliseconds,
+               double volume,
+               bool key_pressed) final;
+  void OnCaptureError(const std::string& message) final;
+
+  // The RenderFrame that will consume the audio data.  Used when creating
+  // AudioInputDevices via the AudioDeviceFactory.
+  const int consumer_render_frame_id_;
+
+  // The StreamDeviceInfo session ID.  Used when creating AudioInputDevices via
+  // the AudioDeviceFactory.
+  const int session_id_;
+
+  // The device created by the AudioDeviceFactory in EnsureSourceIsStarted().
+  scoped_refptr<media::AudioInputDevice> input_device_;
+
+  DISALLOW_COPY_AND_ASSIGN(LocalMediaStreamAudioSource);
+};
+
+}  // namespace content
+
+#endif  // CONTENT_RENDERER_MEDIA_LOCAL_MEDIA_STREAM_AUDIO_SOURCE_H_