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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:
     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   virtual ~Accelerate() {}
     38 
     39   // This method performs the actual Accelerate operation. The samples are
     40   // read from |input|, of length |input_length| elements, and are written to
     41   // |output|. The number of samples removed through time-stretching is
     42   // is provided in the output |length_change_samples|. The method returns
     43   // the outcome of the operation as an enumerator value.
     44   ReturnCodes Process(const int16_t* input,
     45                       size_t input_length,
     46                       AudioMultiVector* output,
     47                       int16_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   virtual void SetParametersForPassiveSpeech(size_t len,
     53                                              int16_t* best_correlation,
     54                                              int* peak_index) const OVERRIDE;
     55 
     56   // Checks the criteria for performing the time-stretching operation and,
     57   // if possible, performs the time-stretching.
     58   virtual ReturnCodes CheckCriteriaAndStretch(
     59       const int16_t* input, size_t input_length, size_t peak_index,
     60       int16_t best_correlation, bool active_speech,
     61       AudioMultiVector* output) const OVERRIDE;
     62 
     63  private:
     64   DISALLOW_COPY_AND_ASSIGN(Accelerate);
     65 };
     66 
     67 struct AccelerateFactory {
     68   AccelerateFactory() {}
     69   virtual ~AccelerateFactory() {}
     70 
     71   virtual Accelerate* Create(int sample_rate_hz,
     72                              size_t num_channels,
     73                              const BackgroundNoise& background_noise) const;
     74 };
     75 
     76 }  // namespace webrtc
     77 #endif  // WEBRTC_MODULES_AUDIO_CODING_NETEQ_ACCELERATE_H_
     78