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_PREEMPTIVE_EXPAND_H_
12 #define WEBRTC_MODULES_AUDIO_CODING_NETEQ_PREEMPTIVE_EXPAND_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 PreemptiveExpand operation. Most of the work is
27 // done in the base class TimeStretch, which is shared with the Accelerate
28 // operation. In the PreemptiveExpand class, the operations that are specific to
29 // PreemptiveExpand are implemented.
30 class PreemptiveExpand : public TimeStretch {
31  public:
PreemptiveExpand(int sample_rate_hz,size_t num_channels,const BackgroundNoise & background_noise,size_t overlap_samples)32   PreemptiveExpand(int sample_rate_hz,
33                    size_t num_channels,
34                    const BackgroundNoise& background_noise,
35                    size_t overlap_samples)
36       : TimeStretch(sample_rate_hz, num_channels, background_noise),
37         old_data_length_per_channel_(0),
38         overlap_samples_(overlap_samples) {
39   }
40 
41   // This method performs the actual PreemptiveExpand operation. The samples are
42   // read from |input|, of length |input_length| elements, and are written to
43   // |output|. The number of samples added through time-stretching is
44   // is provided in the output |length_change_samples|. The method returns
45   // the outcome of the operation as an enumerator value.
46   ReturnCodes Process(const int16_t *pw16_decoded,
47                       size_t len,
48                       size_t old_data_len,
49                       AudioMultiVector* output,
50                       size_t* length_change_samples);
51 
52  protected:
53   // Sets the parameters |best_correlation| and |peak_index| to suitable
54   // values when the signal contains no active speech.
55   void SetParametersForPassiveSpeech(size_t input_length,
56                                      int16_t* best_correlation,
57                                      size_t* peak_index) const override;
58 
59   // Checks the criteria for performing the time-stretching operation and,
60   // if possible, performs the time-stretching.
61   ReturnCodes CheckCriteriaAndStretch(const int16_t* input,
62                                       size_t input_length,
63                                       size_t peak_index,
64                                       int16_t best_correlation,
65                                       bool active_speech,
66                                       bool /*fast_mode*/,
67                                       AudioMultiVector* output) const override;
68 
69  private:
70   size_t old_data_length_per_channel_;
71   size_t overlap_samples_;
72 
73   RTC_DISALLOW_COPY_AND_ASSIGN(PreemptiveExpand);
74 };
75 
76 struct PreemptiveExpandFactory {
PreemptiveExpandFactoryPreemptiveExpandFactory77   PreemptiveExpandFactory() {}
~PreemptiveExpandFactoryPreemptiveExpandFactory78   virtual ~PreemptiveExpandFactory() {}
79 
80   virtual PreemptiveExpand* Create(
81       int sample_rate_hz,
82       size_t num_channels,
83       const BackgroundNoise& background_noise,
84       size_t overlap_samples) const;
85 };
86 
87 }  // namespace webrtc
88 #endif  // WEBRTC_MODULES_AUDIO_CODING_NETEQ_PREEMPTIVE_EXPAND_H_
89