webrtc/common_audio/resampler/sinusoidal_linear_chirp_source.h

/*
 *  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.
 */

// Modified from the Chromium original here:
// src/media/base/sinc_resampler_unittest.cc

#ifndef WEBRTC_COMMON_AUDIO_RESAMPLER_SINUSOIDAL_LINEAR_CHIRP_SOURCE_H_
#define WEBRTC_COMMON_AUDIO_RESAMPLER_SINUSOIDAL_LINEAR_CHIRP_SOURCE_H_

#include "webrtc/base/constructormagic.h"
#include "webrtc/common_audio/resampler/sinc_resampler.h"

namespace webrtc {

// Fake audio source for testing the resampler.  Generates a sinusoidal linear
// chirp (http://en.wikipedia.org/wiki/Chirp) which can be tuned to stress the
// resampler for the specific sample rate conversion being used.
class SinusoidalLinearChirpSource : public SincResamplerCallback {
 public:
  // |delay_samples| can be used to insert a fractional sample delay into the
  // source.  It will produce zeros until non-negative time is reached.
  SinusoidalLinearChirpSource(int sample_rate, int samples,
                              double max_frequency, double delay_samples);

  virtual ~SinusoidalLinearChirpSource() {}

  virtual void Run(int frames, float* destination) OVERRIDE;

  double Frequency(int position);

 private:
  enum {
    kMinFrequency = 5
  };

  double sample_rate_;
  int total_samples_;
  double max_frequency_;
  double k_;
  int current_index_;
  double delay_samples_;

  DISALLOW_COPY_AND_ASSIGN(SinusoidalLinearChirpSource);
};

}  // namespace webrtc

#endif  // WEBRTC_COMMON_AUDIO_RESAMPLER_SINUSOIDAL_LINEAR_CHIRP_SOURCE_H_