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Avoiding overflow in cross correlation in NetEq.

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BUG=

Review-Url: https://codereview.webrtc.org/1908623002
Cr-Commit-Position: refs/heads/master@{#12538}
This commit is contained in:
minyue
2016-04-27 15:06:10 -07:00
committed by Commit bot
parent 8034614b81
commit 3d09dfdbba
21 changed files with 186 additions and 112 deletions
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14
webrtc/modules/audio_coding/neteq/time_stretch.cc
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@ -16,6 +16,7 @@
#include "webrtc/base/safe_conversions.h"
#include "webrtc/common_audio/signal_processing/include/signal_processing_library.h"
#include "webrtc/modules/audio_coding/neteq/background_noise.h"
#include "webrtc/modules/audio_coding/neteq/cross_correlation.h"
#include "webrtc/modules/audio_coding/neteq/dsp_helper.h"
namespace webrtc {
@ -158,20 +159,15 @@ TimeStretch::ReturnCodes TimeStretch::Process(const int16_t* input,
}
void TimeStretch::AutoCorrelation() {
// Set scaling factor for cross correlation to protect against overflow.
int scaling = kLogCorrelationLen - WebRtcSpl_NormW32(
max_input_value_ * max_input_value_);
scaling = std::max(0, scaling);
// Calculate correlation from lag kMinLag to lag kMaxLag in 4 kHz domain.
int32_t auto_corr[kCorrelationLen];
WebRtcSpl_CrossCorrelation(auto_corr, &downsampled_input_[kMaxLag],
&downsampled_input_[kMaxLag - kMinLag],
kCorrelationLen, kMaxLag - kMinLag, scaling, -1);
CrossCorrelationWithAutoShift(
&downsampled_input_[kMaxLag], &downsampled_input_[kMaxLag - kMinLag],
kCorrelationLen, kMaxLag - kMinLag, -1, auto_corr);
// Normalize correlation to 14 bits and write to |auto_correlation_|.
int32_t max_corr = WebRtcSpl_MaxAbsValueW32(auto_corr, kCorrelationLen);
scaling = std::max(0, 17 - WebRtcSpl_NormW32(max_corr));
int scaling = std::max(0, 17 - WebRtcSpl_NormW32(max_corr));
WebRtcSpl_VectorBitShiftW32ToW16(auto_correlation_, kCorrelationLen,
auto_corr, scaling);
}