8fc05feed4
Includes a unittest to ensure we meet the same quality thresholds as SincResampler (modulo quantization error). BUG=webrtc:1395 Review URL: https://webrtc-codereview.appspot.com/1323011 git-svn-id: http://webrtc.googlecode.com/svn/trunk@3909 4adac7df-926f-26a2-2b94-8c16560cd09d
58 lines
1.8 KiB
C++
58 lines
1.8 KiB
C++
/*
|
|
* Copyright (c) 2013 The WebRTC project authors. All Rights Reserved.
|
|
*
|
|
* Use of this source code is governed by a BSD-style license
|
|
* that can be found in the LICENSE file in the root of the source
|
|
* tree. An additional intellectual property rights grant can be found
|
|
* in the file PATENTS. All contributing project authors may
|
|
* be found in the AUTHORS file in the root of the source tree.
|
|
*/
|
|
|
|
// MSVC++ requires this to be set before any other includes to get M_PI.
|
|
#define _USE_MATH_DEFINES
|
|
|
|
#include "webrtc/common_audio/resampler/sinusoidal_linear_chirp_source.h"
|
|
|
|
#include <cmath>
|
|
|
|
namespace webrtc {
|
|
|
|
SinusoidalLinearChirpSource::SinusoidalLinearChirpSource(int sample_rate,
|
|
int samples, double max_frequency, double delay_samples)
|
|
: sample_rate_(sample_rate),
|
|
total_samples_(samples),
|
|
max_frequency_(max_frequency),
|
|
current_index_(0),
|
|
delay_samples_(delay_samples) {
|
|
// Chirp rate.
|
|
double duration = static_cast<double>(total_samples_) / sample_rate_;
|
|
k_ = (max_frequency_ - kMinFrequency) / duration;
|
|
}
|
|
|
|
void SinusoidalLinearChirpSource::Run(float* destination, int frames) {
|
|
for (int i = 0; i < frames; ++i, ++current_index_) {
|
|
// Filter out frequencies higher than Nyquist.
|
|
if (Frequency(current_index_) > 0.5 * sample_rate_) {
|
|
destination[i] = 0;
|
|
} else {
|
|
// Calculate time in seconds.
|
|
double t = (static_cast<double>(current_index_) - delay_samples_) /
|
|
sample_rate_;
|
|
if (t < 0) {
|
|
destination[i] = 0;
|
|
} else {
|
|
// Sinusoidal linear chirp.
|
|
destination[i] =
|
|
sin(2 * M_PI * (kMinFrequency * t + (k_ / 2) * t * t));
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
double SinusoidalLinearChirpSource::Frequency(int position) {
|
|
return kMinFrequency + (position - delay_samples_) *
|
|
(max_frequency_ - kMinFrequency) / total_samples_;
|
|
}
|
|
|
|
} // namespace webrtc
|