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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_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:
     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 {
     77   PreemptiveExpandFactory() {}
     78   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