NetEq: Fix a bug in expand_rate and speech_expand_rate calculation

webrtc/modules/audio_coding/neteq/statistics_calculator.cc

 /*
  *  Copyright (c) 2013 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.
  */
 
 #include "webrtc/modules/audio_coding/neteq/statistics_calculator.h"
 
 #include <assert.h>
 #include <string.h>  // memset
 #include <algorithm>
 
 #include "webrtc/base/checks.h"
 #include "webrtc/base/safe_conversions.h"
 #include "webrtc/modules/audio_coding/neteq/decision_logic.h"
 #include "webrtc/modules/audio_coding/neteq/delay_manager.h"
 #include "webrtc/system_wrappers/include/metrics.h"
 
 namespace webrtc {
 
+namespace {
+size_t AddIntToSizeTWithLowerCap(int a, size_t b) {
+  const size_t ret = b + a;
+  // If a + b is negative, resulting in a negative wrap, cap it to zero instead.
+  static_assert(sizeof(size_t) >= sizeof(int),
+                "int must not be wider than size_t for this to work");

[kwiberg-webrtc, 2017/05/05 11:43:52]

It's up to you, but I'd skip the description. It's obvious from the context.

+  return (a < 0 && ret > b) ? 0 : ret;
+}
+}  // namespace
+
 // Allocating the static const so that it can be passed by reference to
 // RTC_DCHECK.
 const size_t StatisticsCalculator::kLenWaitingTimes;
 
 StatisticsCalculator::PeriodicUmaLogger::PeriodicUmaLogger(
     const std::string& uma_name,
     int report_interval_ms,
     int max_value)
     : uma_name_(uma_name),
       report_interval_ms_(report_interval_ms),
@@ skipping 106 matching lines @@
 }
 
 void StatisticsCalculator::ExpandedVoiceSamples(size_t num_samples) {
   expanded_speech_samples_ += num_samples;
 }
 
 void StatisticsCalculator::ExpandedNoiseSamples(size_t num_samples) {
   expanded_noise_samples_ += num_samples;
 }
 
+void StatisticsCalculator::ExpandedVoiceSamplesCorrection(int num_samples) {
+  expanded_speech_samples_ =
+      AddIntToSizeTWithLowerCap(num_samples, expanded_speech_samples_);
+}
+
+void StatisticsCalculator::ExpandedNoiseSamplesCorrection(int num_samples) {
+  expanded_noise_samples_ =
+      AddIntToSizeTWithLowerCap(num_samples, expanded_noise_samples_);
+}
+
 void StatisticsCalculator::PreemptiveExpandedSamples(size_t num_samples) {
   preemptive_samples_ += num_samples;
 }
 
 void StatisticsCalculator::AcceleratedSamples(size_t num_samples) {
   accelerate_samples_ += num_samples;
 }
 
 void StatisticsCalculator::AddZeros(size_t num_samples) {
   added_zero_samples_ += num_samples;
@@ skipping 127 matching lines @@
     // Ratio must be smaller than 1 in Q14.
     assert((numerator << 14) / denominator < (1 << 14));
     return static_cast<uint16_t>((numerator << 14) / denominator);
   } else {
     // Will not produce a ratio larger than 1, since this is probably an error.
     return 1 << 14;
   }
 }
 
 }  // namespace webrtc