1 /*
2  *  Copyright (c) 2012 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 #ifndef MODULES_AUDIO_CODING_NETEQ_ACCELERATE_H_
12 #define MODULES_AUDIO_CODING_NETEQ_ACCELERATE_H_
13 
14 #include <stddef.h>
15 #include <stdint.h>
16 
17 #include "modules/audio_coding/neteq/time_stretch.h"
18 #include "rtc_base/constructor_magic.h"
19 
20 namespace webrtc {
21 
22 class AudioMultiVector;
23 class BackgroundNoise;
24 
25 // This class implements the Accelerate operation. Most of the work is done
26 // in the base class TimeStretch, which is shared with the PreemptiveExpand
27 // operation. In the Accelerate class, the operations that are specific to
28 // Accelerate are implemented.
29 class Accelerate : public TimeStretch {
30  public:
Accelerate(int sample_rate_hz,size_t num_channels,const BackgroundNoise & background_noise)31   Accelerate(int sample_rate_hz,
32              size_t num_channels,
33              const BackgroundNoise& background_noise)
34       : TimeStretch(sample_rate_hz, num_channels, background_noise) {}
35 
36   // This method performs the actual Accelerate operation. The samples are
37   // read from |input|, of length |input_length| elements, and are written to
38   // |output|. The number of samples removed through time-stretching is
39   // is provided in the output |length_change_samples|. The method returns
40   // the outcome of the operation as an enumerator value. If |fast_accelerate|
41   // is true, the algorithm will relax the requirements on finding strong
42   // correlations, and may remove multiple pitch periods if possible.
43   ReturnCodes Process(const int16_t* input,
44                       size_t input_length,
45                       bool fast_accelerate,
46                       AudioMultiVector* output,
47                       size_t* length_change_samples);
48 
49  protected:
50   // Sets the parameters |best_correlation| and |peak_index| to suitable
51   // values when the signal contains no active speech.
52   void SetParametersForPassiveSpeech(size_t len,
53                                      int16_t* best_correlation,
54                                      size_t* peak_index) const override;
55 
56   // Checks the criteria for performing the time-stretching operation and,
57   // if possible, performs the time-stretching.
58   ReturnCodes CheckCriteriaAndStretch(const int16_t* input,
59                                       size_t input_length,
60                                       size_t peak_index,
61                                       int16_t best_correlation,
62                                       bool active_speech,
63                                       bool fast_mode,
64                                       AudioMultiVector* output) const override;
65 
66  private:
67   RTC_DISALLOW_COPY_AND_ASSIGN(Accelerate);
68 };
69 
70 struct AccelerateFactory {
AccelerateFactoryAccelerateFactory71   AccelerateFactory() {}
~AccelerateFactoryAccelerateFactory72   virtual ~AccelerateFactory() {}
73 
74   virtual Accelerate* Create(int sample_rate_hz,
75                              size_t num_channels,
76                              const BackgroundNoise& background_noise) const;
77 };
78 
79 }  // namespace webrtc
80 #endif  // MODULES_AUDIO_CODING_NETEQ_ACCELERATE_H_
81