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 REMOTING_HOST_AUDIO_SILENCE_DETECTOR_H_
6 #define REMOTING_HOST_AUDIO_SILENCE_DETECTOR_H_
7 
8 #include <stddef.h>
9 #include <stdint.h>
10 
11 
12 namespace remoting {
13 
14 // Helper used in audio capturers to detect and drop silent audio packets.
15 class AudioSilenceDetector {
16  public:
17   // |threshold| is used to specify maximum absolute sample value that should
18   // still be considered as silence.
19   explicit AudioSilenceDetector(int threshold);
20   ~AudioSilenceDetector();
21 
22   void Reset(int sampling_rate, int channels);
23 
24   // Must be called for each new chunk of data. Return true the given packet
25   // is silence should be dropped.
26   bool IsSilence(const int16_t* samples, size_t frames);
27 
28   // The count of channels received from last Reset().
29   int channels() const;
30 
31  private:
32   // Maximum absolute sample value that should still be considered as silence.
33   int threshold_;
34 
35   // Silence period threshold in samples. Silence intervals shorter than this
36   // value are still encoded and sent to the client, so that we don't disrupt
37   // playback by dropping them.
38   int silence_length_max_;
39 
40   // Lengths of the current silence period in samples.
41   int silence_length_;
42 
43   // The count of channels.
44   int channels_;
45 };
46 
47 }  // namespace remoting
48 
49 #endif  // REMOTING_HOST_AUDIO_SILENCE_DETECTOR_H_
50