remoting/host/audio_silence_detector.cc

   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 "remoting/host/audio_silence_detector.h"
   6
   7 #include <stdlib.h>
   8
   9 namespace remoting {
  10
  11 namespace {
  12
  13 // Silence period threshold in seconds. Silence intervals shorter than this
  14 // value are still encoded and sent to the client, so that we don't disrupt
  15 // playback by dropping them.
  16 int kSilencePeriodThresholdSeconds = 1;
  17
  18 }  // namespace
  19
  20 AudioSilenceDetector::AudioSilenceDetector(int threshold)
  21     : threshold_(threshold),
  22       silence_length_max_(0),
  23       silence_length_(0) {
  24   DCHECK_GE(threshold_, 0);
  25 }
  26
  27 AudioSilenceDetector::~AudioSilenceDetector() {
  28 }
  29
  30 void AudioSilenceDetector::Reset(int sampling_rate, int channels) {
  31   DCHECK_GT(sampling_rate, 0);
  32   silence_length_ = 0;
  33   silence_length_max_ =
  34       sampling_rate * channels * kSilencePeriodThresholdSeconds;
  35 }
  36
  37 bool AudioSilenceDetector::IsSilence(const int16* samples,
  38                                      size_t samples_count) {
  39   bool silent_packet = true;
  40   // Potentially this loop can be optimized (e.g. using SSE or adding special
  41   // case for threshold_==0), but it's not worth worrying about because the
  42   // amount of data it processes is relaively small.
  43   for (size_t i = 0; i < samples_count; ++i) {
  44     if (abs(samples[i]) > threshold_) {
  45       silent_packet = false;
  46       break;
  47     }
  48   }
  49
  50   if (!silent_packet) {
  51     silence_length_ = 0;
  52     return false;
  53   }
  54
  55   silence_length_ += samples_count;
  56   return silence_length_ > silence_length_max_;
  57 }
  58
  59 }  // namespace remoting