media/base/fake_audio_render_callback.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 // MSVC++ requires this to be set before any other includes to get M_PI.
   6 #define _USE_MATH_DEFINES
   7
   8 #include <cmath>
   9
  10 #include "media/base/fake_audio_render_callback.h"
  11
  12 namespace media {
  13
  14 FakeAudioRenderCallback::FakeAudioRenderCallback(double step)
  15     : half_fill_(false),
  16       step_(step),
  17       last_audio_delay_milliseconds_(-1),
  18       last_channel_count_(-1),
  19       volume_(1) {
  20   reset();
  21 }
  22
  23 FakeAudioRenderCallback::~FakeAudioRenderCallback() {}
  24
  25 int FakeAudioRenderCallback::Render(AudioBus* audio_bus,
  26                                     int audio_delay_milliseconds) {
  27   last_audio_delay_milliseconds_ = audio_delay_milliseconds;
  28   last_channel_count_ = audio_bus->channels();
  29
  30   int number_of_frames = audio_bus->frames();
  31   if (half_fill_)
  32     number_of_frames /= 2;
  33
  34   // Fill first channel with a sine wave.
  35   for (int i = 0; i < number_of_frames; ++i)
  36     audio_bus->channel(0)[i] = sin(2 * M_PI * (x_ + step_ * i));
  37   x_ += number_of_frames * step_;
  38
  39   // Copy first channel into the rest of the channels.
  40   for (int i = 1; i < audio_bus->channels(); ++i)
  41     memcpy(audio_bus->channel(i), audio_bus->channel(0),
  42            number_of_frames * sizeof(*audio_bus->channel(i)));
  43
  44   return number_of_frames;
  45 }
  46
  47 double FakeAudioRenderCallback::ProvideInput(AudioBus* audio_bus,
  48                                              base::TimeDelta buffer_delay) {
  49   Render(audio_bus, buffer_delay.InMillisecondsF() + 0.5);
  50   return volume_;
  51 }
  52
  53 }  // namespace media