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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                    int overlap_samples)
     36       : TimeStretch(sample_rate_hz, num_channels, background_noise),
     37         old_data_length_per_channel_(-1),
     38         overlap_samples_(overlap_samples) {
     39   }
     40 
     41   virtual ~PreemptiveExpand() {}
     42 
     43   // This method performs the actual PreemptiveExpand operation. The samples are
     44   // read from |input|, of length |input_length| elements, and are written to
     45   // |output|. The number of samples added through time-stretching is
     46   // is provided in the output |length_change_samples|. The method returns
     47   // the outcome of the operation as an enumerator value.
     48   ReturnCodes Process(const int16_t *pw16_decoded,
     49                       int len,
     50                       int old_data_len,
     51                       AudioMultiVector* output,
     52                       int16_t* length_change_samples);
     53 
     54  protected:
     55   // Sets the parameters |best_correlation| and |peak_index| to suitable
     56   // values when the signal contains no active speech.
     57   virtual void SetParametersForPassiveSpeech(size_t len,
     58                                              int16_t* w16_bestCorr,
     59                                              int* w16_bestIndex) const;
     60 
     61   // Checks the criteria for performing the time-stretching operation and,
     62   // if possible, performs the time-stretching.
     63   virtual ReturnCodes CheckCriteriaAndStretch(
     64       const int16_t *pw16_decoded, size_t len, size_t w16_bestIndex,
     65       int16_t w16_bestCorr, bool w16_VAD,
     66       AudioMultiVector* output) const;
     67 
     68  private:
     69   int old_data_length_per_channel_;
     70   int overlap_samples_;
     71 
     72   DISALLOW_COPY_AND_ASSIGN(PreemptiveExpand);
     73 };
     74 
     75 struct PreemptiveExpandFactory {
     76   PreemptiveExpandFactory() {}
     77   virtual ~PreemptiveExpandFactory() {}
     78 
     79   virtual PreemptiveExpand* Create(
     80       int sample_rate_hz,
     81       size_t num_channels,
     82       const BackgroundNoise& background_noise,
     83       int overlap_samples) const;
     84 };
     85 
     86 }  // namespace webrtc
     87 #endif  // WEBRTC_MODULES_AUDIO_CODING_NETEQ_PREEMPTIVE_EXPAND_H_
     88