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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_EXPAND_H_
     12 #define WEBRTC_MODULES_AUDIO_CODING_NETEQ_EXPAND_H_
     13 
     14 #include <assert.h>
     15 
     16 #include "webrtc/base/constructormagic.h"
     17 #include "webrtc/base/scoped_ptr.h"
     18 #include "webrtc/modules/audio_coding/neteq/audio_multi_vector.h"
     19 #include "webrtc/typedefs.h"
     20 
     21 namespace webrtc {
     22 
     23 // Forward declarations.
     24 class BackgroundNoise;
     25 class RandomVector;
     26 class StatisticsCalculator;
     27 class SyncBuffer;
     28 
     29 // This class handles extrapolation of audio data from the sync_buffer to
     30 // produce packet-loss concealment.
     31 // TODO(hlundin): Refactor this class to divide the long methods into shorter
     32 // ones.
     33 class Expand {
     34  public:
     35   Expand(BackgroundNoise* background_noise,
     36          SyncBuffer* sync_buffer,
     37          RandomVector* random_vector,
     38          StatisticsCalculator* statistics,
     39          int fs,
     40          size_t num_channels);
     41 
     42   virtual ~Expand();
     43 
     44   // Resets the object.
     45   virtual void Reset();
     46 
     47   // The main method to produce concealment data. The data is appended to the
     48   // end of |output|.
     49   virtual int Process(AudioMultiVector* output);
     50 
     51   // Prepare the object to do extra expansion during normal operation following
     52   // a period of expands.
     53   virtual void SetParametersForNormalAfterExpand();
     54 
     55   // Prepare the object to do extra expansion during merge operation following
     56   // a period of expands.
     57   virtual void SetParametersForMergeAfterExpand();
     58 
     59   // Returns the mute factor for |channel|.
     60   int16_t MuteFactor(size_t channel) {
     61     assert(channel < num_channels_);
     62     return channel_parameters_[channel].mute_factor;
     63   }
     64 
     65   // Accessors and mutators.
     66   virtual size_t overlap_length() const;
     67   size_t max_lag() const { return max_lag_; }
     68 
     69  protected:
     70   static const int kMaxConsecutiveExpands = 200;
     71   void GenerateRandomVector(int16_t seed_increment,
     72                             size_t length,
     73                             int16_t* random_vector);
     74 
     75   void GenerateBackgroundNoise(int16_t* random_vector,
     76                                size_t channel,
     77                                int mute_slope,
     78                                bool too_many_expands,
     79                                size_t num_noise_samples,
     80                                int16_t* buffer);
     81 
     82   // Initializes member variables at the beginning of an expand period.
     83   void InitializeForAnExpandPeriod();
     84 
     85   bool TooManyExpands();
     86 
     87   // Analyzes the signal history in |sync_buffer_|, and set up all parameters
     88   // necessary to produce concealment data.
     89   void AnalyzeSignal(int16_t* random_vector);
     90 
     91   RandomVector* const random_vector_;
     92   SyncBuffer* const sync_buffer_;
     93   bool first_expand_;
     94   const int fs_hz_;
     95   const size_t num_channels_;
     96   int consecutive_expands_;
     97 
     98  private:
     99   static const size_t kUnvoicedLpcOrder = 6;
    100   static const size_t kNumCorrelationCandidates = 3;
    101   static const size_t kDistortionLength = 20;
    102   static const size_t kLpcAnalysisLength = 160;
    103   static const size_t kMaxSampleRate = 48000;
    104   static const int kNumLags = 3;
    105 
    106   struct ChannelParameters {
    107     ChannelParameters();
    108     int16_t mute_factor;
    109     int16_t ar_filter[kUnvoicedLpcOrder + 1];
    110     int16_t ar_filter_state[kUnvoicedLpcOrder];
    111     int16_t ar_gain;
    112     int16_t ar_gain_scale;
    113     int16_t voice_mix_factor; /* Q14 */
    114     int16_t current_voice_mix_factor; /* Q14 */
    115     AudioVector expand_vector0;
    116     AudioVector expand_vector1;
    117     bool onset;
    118     int mute_slope; /* Q20 */
    119   };
    120 
    121   // Calculate the auto-correlation of |input|, with length |input_length|
    122   // samples. The correlation is calculated from a downsampled version of
    123   // |input|, and is written to |output|. The scale factor is written to
    124   // |output_scale|.
    125   void Correlation(const int16_t* input,
    126                    size_t input_length,
    127                    int16_t* output,
    128                    int* output_scale) const;
    129 
    130   void UpdateLagIndex();
    131 
    132   BackgroundNoise* const background_noise_;
    133   StatisticsCalculator* const statistics_;
    134   const size_t overlap_length_;
    135   size_t max_lag_;
    136   size_t expand_lags_[kNumLags];
    137   int lag_index_direction_;
    138   int current_lag_index_;
    139   bool stop_muting_;
    140   size_t expand_duration_samples_;
    141   rtc::scoped_ptr<ChannelParameters[]> channel_parameters_;
    142 
    143   RTC_DISALLOW_COPY_AND_ASSIGN(Expand);
    144 };
    145 
    146 struct ExpandFactory {
    147   ExpandFactory() {}
    148   virtual ~ExpandFactory() {}
    149 
    150   virtual Expand* Create(BackgroundNoise* background_noise,
    151                          SyncBuffer* sync_buffer,
    152                          RandomVector* random_vector,
    153                          StatisticsCalculator* statistics,
    154                          int fs,
    155                          size_t num_channels) const;
    156 };
    157 
    158 }  // namespace webrtc
    159 #endif  // WEBRTC_MODULES_AUDIO_CODING_NETEQ_EXPAND_H_
    160