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bb547203bf
In order to eliminate the WebRTC Subtree mirror in Chromium, WebRTC is moving the content of the src/webrtc directory up to the src/ directory. NOPRESUBMIT=true NOTREECHECKS=true NOTRY=true TBR=tommi@webrtc.org Bug: chromium:611808 Change-Id: Iac59c5b51b950f174119565bac87955a7994bc38 Reviewed-on: https://webrtc-review.googlesource.com/1560 Commit-Queue: Mirko Bonadei <mbonadei@webrtc.org> Reviewed-by: Henrik Kjellander <kjellander@webrtc.org> Cr-Commit-Position: refs/heads/master@{#19845}
89 lines
2.8 KiB
C
89 lines
2.8 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_HpOutput.c
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******************************************************************/
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#include "defines.h"
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/*----------------------------------------------------------------*
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* high-pass filter of output and *2 with saturation
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*---------------------------------------------------------------*/
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void WebRtcIlbcfix_HpOutput(
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int16_t *signal, /* (i/o) signal vector */
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int16_t *ba, /* (i) B- and A-coefficients (2:nd order)
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{b[0] b[1] b[2] -a[1] -a[2]} a[0]
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is assumed to be 1.0 */
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int16_t *y, /* (i/o) Filter state yhi[n-1] ylow[n-1]
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yhi[n-2] ylow[n-2] */
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int16_t *x, /* (i/o) Filter state x[n-1] x[n-2] */
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size_t len) /* (i) Number of samples to filter */
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{
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size_t i;
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int32_t tmpW32;
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int32_t tmpW32b;
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for (i=0; i<len; i++) {
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/*
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y[i] = b[0]*x[i] + b[1]*x[i-1] + b[2]*x[i-2]
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+ (-a[1])*y[i-1] + (-a[2])*y[i-2];
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*/
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tmpW32 = y[1] * ba[3]; /* (-a[1])*y[i-1] (low part) */
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tmpW32 += y[3] * ba[4]; /* (-a[2])*y[i-2] (low part) */
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tmpW32 = (tmpW32>>15);
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tmpW32 += y[0] * ba[3]; /* (-a[1])*y[i-1] (high part) */
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tmpW32 += y[2] * ba[4]; /* (-a[2])*y[i-2] (high part) */
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tmpW32 *= 2;
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tmpW32 += signal[i] * ba[0]; /* b[0]*x[0] */
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tmpW32 += x[0] * ba[1]; /* b[1]*x[i-1] */
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tmpW32 += x[1] * ba[2]; /* b[2]*x[i-2] */
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/* Update state (input part) */
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x[1] = x[0];
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x[0] = signal[i];
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/* Rounding in Q(12-1), i.e. add 2^10 */
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tmpW32b = tmpW32 + 1024;
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/* Saturate (to 2^26) so that the HP filtered signal does not overflow */
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tmpW32b = WEBRTC_SPL_SAT((int32_t)67108863, tmpW32b, (int32_t)-67108864);
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/* Convert back to Q0 and multiply with 2 */
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signal[i] = (int16_t)(tmpW32b >> 11);
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/* Update state (filtered part) */
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y[2] = y[0];
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y[3] = y[1];
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/* upshift tmpW32 by 3 with saturation */
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if (tmpW32>268435455) {
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tmpW32 = WEBRTC_SPL_WORD32_MAX;
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} else if (tmpW32<-268435456) {
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tmpW32 = WEBRTC_SPL_WORD32_MIN;
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} else {
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tmpW32 *= 8;
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}
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y[0] = (int16_t)(tmpW32 >> 16);
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y[1] = (int16_t)((tmpW32 & 0xffff) >> 1);
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}
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return;
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}
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