Avoid overflow in NetEq's TimeStretch::SpeechDetection

webrtc/modules/audio_coding/neteq/time_stretch.cc

 /*
  *  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 164 matching lines @@
 bool TimeStretch::SpeechDetection(int32_t vec1_energy, int32_t vec2_energy,
                                   size_t peak_index, int scaling) const {
   // Check if the signal seems to be active speech or not (simple VAD).
   // If (vec1_energy + vec2_energy) / (2 * peak_index) <=
   // 8 * background_noise_energy, then we say that the signal contains no
   // active speech.
   // Rewrite the inequality as:
   // (vec1_energy + vec2_energy) / 16 <= peak_index * background_noise_energy.
   // The two sides of the inequality will be denoted |left_side| and
   // |right_side|.
-  int32_t left_side = (vec1_energy + vec2_energy) / 16;
+  int32_t left_side = rtc::saturated_cast<int32_t>(
+      (static_cast<int64_t>(vec1_energy) + vec2_energy) / 16);
   int32_t right_side;
   if (background_noise_.initialized()) {
     right_side = background_noise_.Energy(master_channel_);
   } else {
     // If noise parameters have not been estimated, use a fixed threshold.
     right_side = 75000;
   }
   int right_scale = 16 - WebRtcSpl_NormW32(right_side);
   right_scale = std::max(0, right_scale);
   left_side = left_side >> right_scale;
   right_side =
       rtc::checked_cast<int32_t>(peak_index) * (right_side >> right_scale);
 
   // Scale |left_side| properly before comparing with |right_side|.
   // (|scaling| is the scale factor before energy calculation, thus the scale
   // factor for the energy is 2 * scaling.)
   if (WebRtcSpl_NormW32(left_side) < 2 * scaling) {
     // Cannot scale only |left_side|, must scale |right_side| too.
     int temp_scale = WebRtcSpl_NormW32(left_side);
     left_side = left_side << temp_scale;
     right_side = right_side >> (2 * scaling - temp_scale);
   } else {
     left_side = left_side << 2 * scaling;
   }
   return left_side > right_side;
 }
 
 }  // namespace webrtc