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       volume_(1) {
  19   reset();
  20 }
  21
  22 FakeAudioRenderCallback::~FakeAudioRenderCallback() {}
  23
  24 int FakeAudioRenderCallback::Render(AudioBus* audio_bus,
  25                                     int audio_delay_milliseconds) {
  26   last_audio_delay_milliseconds_ = audio_delay_milliseconds;
  27   int number_of_frames = audio_bus->frames();
  28   if (half_fill_)
  29     number_of_frames /= 2;
  30
  31   // Fill first channel with a sine wave.
  32   for (int i = 0; i < number_of_frames; ++i)
  33     audio_bus->channel(0)[i] = sin(2 * M_PI * (x_ + step_ * i));
  34   x_ += number_of_frames * step_;
  35
  36   // Copy first channel into the rest of the channels.
  37   for (int i = 1; i < audio_bus->channels(); ++i)
  38     memcpy(audio_bus->channel(i), audio_bus->channel(0),
  39            number_of_frames * sizeof(*audio_bus->channel(i)));
  40
  41   return number_of_frames;
  42 }
  43
  44 double FakeAudioRenderCallback::ProvideInput(AudioBus* audio_bus,
  45                                              base::TimeDelta buffer_delay) {
  46   Render(audio_bus, buffer_delay.InMillisecondsF() + 0.5);
  47   return volume_;
  48 }
  49
  50 }  // namespace media