63 lines
1.7 KiB
C
63 lines
1.7 KiB
C
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/*
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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_Vq4.c
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******************************************************************/
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#include "modules/audio_coding/codecs/ilbc/vq4.h"
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#include "modules/audio_coding/codecs/ilbc/constants.h"
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/*----------------------------------------------------------------*
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* vector quantization
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*---------------------------------------------------------------*/
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void WebRtcIlbcfix_Vq4(
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int16_t *Xq, /* quantized vector (Q13) */
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int16_t *index,
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int16_t *CB, /* codebook in Q13 */
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int16_t *X, /* vector to quantize (Q13) */
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int16_t n_cb
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){
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int16_t i, j;
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int16_t pos, minindex=0;
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int16_t tmp;
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int32_t dist, mindist;
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pos = 0;
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mindist = WEBRTC_SPL_WORD32_MAX; /* start value */
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/* Find the codebook with the lowest square distance */
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for (j = 0; j < n_cb; j++) {
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tmp = X[0] - CB[pos];
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dist = tmp * tmp;
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for (i = 1; i < 4; i++) {
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tmp = X[i] - CB[pos + i];
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dist += tmp * tmp;
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}
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if (dist < mindist) {
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mindist = dist;
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minindex = j;
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}
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pos += 4;
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}
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/* Store the quantized codebook and the index */
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for (i = 0; i < 4; i++) {
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Xq[i] = CB[minindex*4 + i];
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}
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*index = minindex;
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}
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