1 /*
2  *  Copyright (c) 2013 The WebRTC project authors. All Rights Reserved.
3  *
4  *  Use of this source code is governed by a BSD-style license
5  *  that can be found in the LICENSE file in the root of the source
6  *  tree. An additional intellectual property rights grant can be found
7  *  in the file PATENTS.  All contributing project authors may
8  *  be found in the AUTHORS file in the root of the source tree.
9  */
10 
11 // Modified from the Chromium original here:
12 // src/media/base/sinc_resampler_unittest.cc
13 
14 #ifndef COMMON_AUDIO_RESAMPLER_SINUSOIDAL_LINEAR_CHIRP_SOURCE_H_
15 #define COMMON_AUDIO_RESAMPLER_SINUSOIDAL_LINEAR_CHIRP_SOURCE_H_
16 
17 #include "common_audio/resampler/sinc_resampler.h"
18 #include "rtc_base/constructormagic.h"
19 
20 namespace webrtc {
21 
22 // Fake audio source for testing the resampler.  Generates a sinusoidal linear
23 // chirp (http://en.wikipedia.org/wiki/Chirp) which can be tuned to stress the
24 // resampler for the specific sample rate conversion being used.
25 class SinusoidalLinearChirpSource : public SincResamplerCallback {
26  public:
27   // |delay_samples| can be used to insert a fractional sample delay into the
28   // source.  It will produce zeros until non-negative time is reached.
29   SinusoidalLinearChirpSource(int sample_rate,
30                               size_t samples,
31                               double max_frequency,
32                               double delay_samples);
33 
~SinusoidalLinearChirpSource()34   ~SinusoidalLinearChirpSource() override {}
35 
36   void Run(size_t frames, float* destination) override;
37 
38   double Frequency(size_t position);
39 
40  private:
41   enum { kMinFrequency = 5 };
42 
43   int sample_rate_;
44   size_t total_samples_;
45   double max_frequency_;
46   double k_;
47   size_t current_index_;
48   double delay_samples_;
49 
50   RTC_DISALLOW_COPY_AND_ASSIGN(SinusoidalLinearChirpSource);
51 };
52 
53 }  // namespace webrtc
54 
55 #endif  // COMMON_AUDIO_RESAMPLER_SINUSOIDAL_LINEAR_CHIRP_SOURCE_H_
56