Avoiding overflow in cross correlation in NetEq.

webrtc/modules/audio_coding/neteq/merge.h

 /*
  *  Copyright (c) 2012 The WebRTC project authors. All Rights Reserved.
  *
  *  Use of this source code is governed by a BSD-style license
  *  that can be found in the LICENSE file in the root of the source
  *  tree. An additional intellectual property rights grant can be found
  *  in the file PATENTS.  All contributing project authors may
  *  be found in the AUTHORS file in the root of the source tree.
  */
 
@@ skipping 51 matching lines @@
   static const size_t kInputDownsampLength = 40;
   static const size_t kMaxCorrelationLength = 60;
 
   // Calls |expand_| to get more expansion data to merge with. The data is
   // written to |expanded_signal_|. Returns the length of the expanded data,
   // while |expand_period| will be the number of samples in one expansion period
   // (typically one pitch period). The value of |old_length| will be the number
   // of samples that were taken from the |sync_buffer_|.
   size_t GetExpandedSignal(size_t* old_length, size_t* expand_period);
 
-  // Analyzes |input| and |expanded_signal| to find maximum values. Returns
-  // a muting factor (Q14) to be used on the new data.
+  // Analyzes |input| and |expanded_signal| and returns muting factor (Q14) to
+  // be used on the new data.
   int16_t SignalScaling(const int16_t* input, size_t input_length,
-                        const int16_t* expanded_signal,
-                        int16_t* expanded_max, int16_t* input_max) const;
+                        const int16_t* expanded_signal) const;
 
   // Downsamples |input| (|input_length| samples) and |expanded_signal| to
   // 4 kHz sample rate. The downsampled signals are written to
   // |input_downsampled_| and |expanded_downsampled_|, respectively.
   void Downsample(const int16_t* input, size_t input_length,
                   const int16_t* expanded_signal, size_t expanded_length);
 
   // Calculates cross-correlation between |input_downsampled_| and
   // |expanded_downsampled_|, and finds the correlation maximum. The maximizing
   // lag is returned.
-  size_t CorrelateAndPeakSearch(int16_t expanded_max, int16_t input_max,
-                                size_t start_position, size_t input_length,
+  size_t CorrelateAndPeakSearch(size_t start_position, size_t input_length,
                                 size_t expand_period) const;
 
   const int fs_mult_;  // fs_hz_ / 8000.
   const size_t timestamps_per_call_;
   Expand* expand_;
   SyncBuffer* sync_buffer_;
   int16_t expanded_downsampled_[kExpandDownsampLength];
   int16_t input_downsampled_[kInputDownsampLength];
   AudioMultiVector expanded_;
 
   RTC_DISALLOW_COPY_AND_ASSIGN(Merge);
 };
 
 }  // namespace webrtc
 #endif  // WEBRTC_MODULES_AUDIO_CODING_NETEQ_MERGE_H_