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 // MSVC++ requires this to be set before any other includes to get M_PI.
5 #define _USE_MATH_DEFINES
6 #include <cmath>
7
8 #include "media/audio/simple_sources.h"
9
10 #include <algorithm>
11
12 #include "base/logging.h"
13
14 namespace media {
15
16 //////////////////////////////////////////////////////////////////////////////
17 // SineWaveAudioSource implementation.
18
SineWaveAudioSource(int channels,double freq,double sample_freq)19 SineWaveAudioSource::SineWaveAudioSource(int channels,
20 double freq, double sample_freq)
21 : channels_(channels),
22 f_(freq / sample_freq),
23 time_state_(0),
24 cap_(0),
25 callbacks_(0),
26 errors_(0) {
27 }
28
29 // The implementation could be more efficient if a lookup table is constructed
30 // but it is efficient enough for our simple needs.
OnMoreData(AudioBus * audio_bus,AudioBuffersState audio_buffers)31 int SineWaveAudioSource::OnMoreData(AudioBus* audio_bus,
32 AudioBuffersState audio_buffers) {
33 base::AutoLock auto_lock(time_lock_);
34 callbacks_++;
35
36 // The table is filled with s(t) = kint16max*sin(Theta*t),
37 // where Theta = 2*PI*fs.
38 // We store the discrete time value |t| in a member to ensure that the
39 // next pass starts at a correct state.
40 int max_frames = cap_ > 0 ?
41 std::min(audio_bus->frames(), cap_ - time_state_) : audio_bus->frames();
42 for (int i = 0; i < max_frames; ++i)
43 audio_bus->channel(0)[i] = sin(2.0 * M_PI * f_ * time_state_++);
44 for (int i = 1; i < audio_bus->channels(); ++i) {
45 memcpy(audio_bus->channel(i), audio_bus->channel(0),
46 max_frames * sizeof(*audio_bus->channel(i)));
47 }
48 return max_frames;
49 }
50
OnError(AudioOutputStream * stream)51 void SineWaveAudioSource::OnError(AudioOutputStream* stream) {
52 errors_++;
53 }
54
CapSamples(int cap)55 void SineWaveAudioSource::CapSamples(int cap) {
56 base::AutoLock auto_lock(time_lock_);
57 DCHECK_GT(cap, 0);
58 cap_ = cap;
59 }
60
Reset()61 void SineWaveAudioSource::Reset() {
62 base::AutoLock auto_lock(time_lock_);
63 time_state_ = 0;
64 }
65
66 } // namespace media
67