content/renderer/media/media_stream_audio_level_calculator.h

   1 // Copyright 2014 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_MEDIA_STREAM_AUDIO_LEVEL_CALCULATOR_H_
   6 #define CONTENT_RENDERER_MEDIA_MEDIA_STREAM_AUDIO_LEVEL_CALCULATOR_H_
   7
   8 #include "base/threading/thread_checker.h"
   9
  10 namespace content {
  11
  12 // This class is used by the WebRtcLocalAudioTrack to calculate the  level of
  13 // the audio signal. And the audio level will be eventually used by the volume
  14 // animation UI.
  15 // The algorithm used by this class is the same as how it is done in
  16 // third_party/webrtc/voice_engine/level_indicator.cc.
  17 class MediaStreamAudioLevelCalculator {
  18  public:
  19   MediaStreamAudioLevelCalculator();
  20   ~MediaStreamAudioLevelCalculator();
  21
  22   // Calculates the signal level of the audio data.
  23   // Returns the absolute value of the amplitude of the signal.
  24   int Calculate(const int16* audio_data, int number_of_channels,
  25                 int number_of_frames);
  26
  27  private:
  28   // Used to DCHECK that the constructor and Calculate() are always called on
  29   // the same audio thread. Note that the destructor will be called on a
  30   // different thread, which can be either the main render thread or a new
  31   // audio thread where WebRtcLocalAudioTrack::OnSetFormat() is called.
  32   base::ThreadChecker thread_checker_;
  33
  34   int counter_;
  35   int max_amplitude_;
  36   int level_;
  37 };
  38
  39 }  // namespace content
  40
  41 #endif  // CONTENT_RENDERER_MEDIA_MEDIA_STREAM_AUDIO_LEVEL_CALCULATOR_H_