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// Copyright (c) 2012 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
// MSVC++ requires this to be set before any other includes to get M_PI.
#define _USE_MATH_DEFINES
#include <cmath>
#include "media/audio/simple_sources.h"
#include <algorithm>
#include "base/logging.h"
namespace media {
//////////////////////////////////////////////////////////////////////////////
// SineWaveAudioSource implementation.
SineWaveAudioSource::SineWaveAudioSource(int channels,
double freq, double sample_freq)
: channels_(channels),
f_(freq / sample_freq),
time_state_(0),
cap_(0),
callbacks_(0),
errors_(0) {
}
// The implementation could be more efficient if a lookup table is constructed
// but it is efficient enough for our simple needs.
int SineWaveAudioSource::OnMoreData(AudioBus* audio_bus,
uint32 total_bytes_delay) {
base::AutoLock auto_lock(time_lock_);
callbacks_++;
// The table is filled with s(t) = kint16max*sin(Theta*t),
// where Theta = 2*PI*fs.
// We store the discrete time value |t| in a member to ensure that the
// next pass starts at a correct state.
int max_frames = cap_ > 0 ?
std::min(audio_bus->frames(), cap_ - time_state_) : audio_bus->frames();
for (int i = 0; i < max_frames; ++i)
audio_bus->channel(0)[i] = sin(2.0 * M_PI * f_ * time_state_++);
for (int i = 1; i < audio_bus->channels(); ++i) {
memcpy(audio_bus->channel(i), audio_bus->channel(0),
max_frames * sizeof(*audio_bus->channel(i)));
}
return max_frames;
}
void SineWaveAudioSource::OnError(AudioOutputStream* stream) {
errors_++;
}
void SineWaveAudioSource::CapSamples(int cap) {
base::AutoLock auto_lock(time_lock_);
DCHECK_GT(cap, 0);
cap_ = cap;
}
void SineWaveAudioSource::Reset() {
base::AutoLock auto_lock(time_lock_);
time_state_ = 0;
}
} // namespace media
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