50 lines
1.7 KiB
C
50 lines
1.7 KiB
C
/*
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* Copyright (c) 2011 The WebRTC project authors. All Rights Reserved.
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*
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* Use of this source code is governed by a BSD-style license
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* that can be found in the LICENSE file in the root of the source
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* tree. An additional intellectual property rights grant can be found
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* in the file PATENTS. All contributing project authors may
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* be found in the AUTHORS file in the root of the source tree.
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*/
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/******************************************************************
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iLBC Speech Coder ANSI-C Source Code
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WebRtcIlbcfix_CompCorr.c
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******************************************************************/
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#include "defines.h"
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/*----------------------------------------------------------------*
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* Compute cross correlation and pitch gain for pitch prediction
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* of last subframe at given lag.
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*---------------------------------------------------------------*/
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void WebRtcIlbcfix_CompCorr(
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WebRtc_Word32 *corr, /* (o) cross correlation */
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WebRtc_Word32 *ener, /* (o) energy */
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WebRtc_Word16 *buffer, /* (i) signal buffer */
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WebRtc_Word16 lag, /* (i) pitch lag */
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WebRtc_Word16 bLen, /* (i) length of buffer */
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WebRtc_Word16 sRange, /* (i) correlation search length */
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WebRtc_Word16 scale /* (i) number of rightshifts to use */
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){
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WebRtc_Word16 *w16ptr;
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w16ptr=&buffer[bLen-sRange-lag];
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/* Calculate correlation and energy */
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(*corr)=WebRtcSpl_DotProductWithScale(&buffer[bLen-sRange], w16ptr, sRange, scale);
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(*ener)=WebRtcSpl_DotProductWithScale(w16ptr, w16ptr, sRange, scale);
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/* For zero energy set the energy to 0 in order to avoid potential
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problems for coming divisions */
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if (*ener == 0) {
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*corr = 0;
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*ener = 1;
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}
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}
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