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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 WEBRTC_MODULES_AUDIO_CODING_NETEQ_ACCELERATE_H_
12 #define WEBRTC_MODULES_AUDIO_CODING_NETEQ_ACCELERATE_H_
13 
14 #include <assert.h>
15 
16 #include "webrtc/base/constructormagic.h"
17 #include "webrtc/modules/audio_coding/neteq/audio_multi_vector.h"
18 #include "webrtc/modules/audio_coding/neteq/time_stretch.h"
19 #include "webrtc/typedefs.h"
20 
21 namespace webrtc {
22 
23 // Forward declarations.
24 class BackgroundNoise;
25 
26 // This class implements the Accelerate operation. Most of the work is done
27 // in the base class TimeStretch, which is shared with the PreemptiveExpand
28 // operation. In the Accelerate class, the operations that are specific to
29 // Accelerate are implemented.
30 class Accelerate : public TimeStretch {
31  public:
Accelerate(int sample_rate_hz,size_t num_channels,const BackgroundNoise & background_noise)32   Accelerate(int sample_rate_hz, size_t num_channels,
33              const BackgroundNoise& background_noise)
34       : TimeStretch(sample_rate_hz, num_channels, background_noise) {
35   }
36 
37   // This method performs the actual Accelerate operation. The samples are
38   // read from |input|, of length |input_length| elements, and are written to
39   // |output|. The number of samples removed through time-stretching is
40   // is provided in the output |length_change_samples|. The method returns
41   // the outcome of the operation as an enumerator value. If |fast_accelerate|
42   // is true, the algorithm will relax the requirements on finding strong
43   // correlations, and may remove multiple pitch periods if possible.
44   ReturnCodes Process(const int16_t* input,
45                       size_t input_length,
46                       bool fast_accelerate,
47                       AudioMultiVector* output,
48                       size_t* length_change_samples);
49 
50  protected:
51   // Sets the parameters |best_correlation| and |peak_index| to suitable
52   // values when the signal contains no active speech.
53   void SetParametersForPassiveSpeech(size_t len,
54                                      int16_t* best_correlation,
55                                      size_t* peak_index) const override;
56 
57   // Checks the criteria for performing the time-stretching operation and,
58   // if possible, performs the time-stretching.
59   ReturnCodes CheckCriteriaAndStretch(const int16_t* input,
60                                       size_t input_length,
61                                       size_t peak_index,
62                                       int16_t best_correlation,
63                                       bool active_speech,
64                                       bool fast_mode,
65                                       AudioMultiVector* output) const override;
66 
67  private:
68   RTC_DISALLOW_COPY_AND_ASSIGN(Accelerate);
69 };
70 
71 struct AccelerateFactory {
AccelerateFactoryAccelerateFactory72   AccelerateFactory() {}
~AccelerateFactoryAccelerateFactory73   virtual ~AccelerateFactory() {}
74 
75   virtual Accelerate* Create(int sample_rate_hz,
76                              size_t num_channels,
77                              const BackgroundNoise& background_noise) const;
78 };
79 
80 }  // namespace webrtc
81 #endif  // WEBRTC_MODULES_AUDIO_CODING_NETEQ_ACCELERATE_H_
82