Update audio code to use size_t more correctly,

webrtc/modules/audio_coding/neteq/time_stretch.cc

Index: webrtc/modules/audio_coding/neteq/time_stretch.cc
diff --git a/webrtc/modules/audio_coding/neteq/time_stretch.cc b/webrtc/modules/audio_coding/neteq/time_stretch.cc
index 5577cd2ecbbd80886e7cda49a9d050417bc7e407..b129b4eed79c722b1959dc326812060bdfa877cb 100644
--- a/webrtc/modules/audio_coding/neteq/time_stretch.cc
+++ b/webrtc/modules/audio_coding/neteq/time_stretch.cc
@@ -23,9 +23,9 @@ TimeStretch::ReturnCodes TimeStretch::Process(const int16_t* input,
                                               size_t input_len,
                                               bool fast_mode,
                                               AudioMultiVector* output,
-                                              int16_t* length_change_samples) {
+                                              size_t* length_change_samples) {
   // Pre-calculate common multiplication with |fs_mult_|.
-  int fs_mult_120 = fs_mult_ * 120;  // Corresponds to 15 ms.
+  size_t fs_mult_120 = fs_mult_ * 120;  // Corresponds to 15 ms.

[hlundin-webrtc, 2015/08/10 11:30:02]

int

 
   const int16_t* signal;
   rtc::scoped_ptr<int16_t[]> signal_array;
@@ -48,8 +48,7 @@ TimeStretch::ReturnCodes TimeStretch::Process(const int16_t* input,
   }
 
   // Find maximum absolute value of input signal.
-  max_input_value_ = WebRtcSpl_MaxAbsValueW16(signal,
-                                              static_cast<int>(signal_len));
+  max_input_value_ = WebRtcSpl_MaxAbsValueW16(signal, signal_len);
 
   // Downsample to 4 kHz sample rate and calculate auto-correlation.
   DspHelper::DownsampleTo4kHz(signal, signal_len, kDownsampledLen,
@@ -58,13 +57,12 @@ TimeStretch::ReturnCodes TimeStretch::Process(const int16_t* input,
   AutoCorrelation();
 
   // Find the strongest correlation peak.
-  static const int kNumPeaks = 1;
-  int peak_index;
+  static const size_t kNumPeaks = 1;
+  size_t peak_index;
   int16_t peak_value;
   DspHelper::PeakDetection(auto_correlation_, kCorrelationLen, kNumPeaks,
                            fs_mult_, &peak_index, &peak_value);
   // Assert that |peak_index| stays within boundaries.
-  assert(peak_index >= 0);
   assert(peak_index <= (2 * kCorrelationLen - 1) * fs_mult_);
 
   // Compensate peak_index for displaced starting position. The displacement
@@ -79,7 +77,7 @@ TimeStretch::ReturnCodes TimeStretch::Process(const int16_t* input,
   // Calculate scaling to ensure that |peak_index| samples can be square-summed
   // without overflowing.
   int scaling = 31 - WebRtcSpl_NormW32(max_input_value_ * max_input_value_) -
-      WebRtcSpl_NormW32(peak_index);
+      WebRtcSpl_NormW32(static_cast<int32_t>(peak_index));

[hlundin-webrtc, 2015/08/10 11:30:02]

rtc::checked_cast

[Peter Kasting, 2015/08/17 22:49:47]

This shouldn't be necessary, as the asserts above guarantee that peak_index <=
119 * fs_mult_, which should fit in an int32_t.

[hlundin-webrtc, 2015/08/18 07:19:18]

Acknowledged.

   scaling = std::max(0, scaling);
 
   // |vec1| starts at 15 ms minus one pitch period.
@@ -177,7 +175,7 @@ void TimeStretch::AutoCorrelation() {
 }
 
 bool TimeStretch::SpeechDetection(int32_t vec1_energy, int32_t vec2_energy,
-                                  int peak_index, int scaling) const {
+                                  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
@@ -197,7 +195,7 @@ bool TimeStretch::SpeechDetection(int32_t vec1_energy, int32_t vec2_energy,
   int right_scale = 16 - WebRtcSpl_NormW32(right_side);
   right_scale = std::max(0, right_scale);
   left_side = left_side >> right_scale;
-  right_side = peak_index * (right_side >> right_scale);
+  right_side = static_cast<int32_t>(peak_index) * (right_side >> right_scale);

[hlundin-webrtc, 2015/08/10 11:30:02]

rtc::checked_cast

[Peter Kasting, 2015/08/17 22:49:47]

While today this shouldn't be necessary as |peak_index| is guaranteed to fit in
an int32_t by the caller (see reply above), I suppose in the future someone
could change that.  I could change the function to take an int32_t instead, but
that seems more confusing, when the rest of the file uses a size_t for this
concept.  So, done.

[hlundin-webrtc, 2015/08/18 07:19:18]

Thanks. Future changes is what worries me sometimes.

 
   // Scale |left_side| properly before comparing with |right_side|.
   // (|scaling| is the scale factor before energy calculation, thus the scale