webrtc/modules/audio_coding/codecs/iLBC/main/source/vq4.c

63 lines
1.7 KiB
C

/*
* Copyright (c) 2011 The WebRTC project authors. All Rights Reserved.
*
* Use of this source code is governed by a BSD-style license
* that can be found in the LICENSE file in the root of the source
* tree. An additional intellectual property rights grant can be found
* in the file PATENTS. All contributing project authors may
* be found in the AUTHORS file in the root of the source tree.
*/
/******************************************************************
iLBC Speech Coder ANSI-C Source Code
WebRtcIlbcfix_Vq4.c
******************************************************************/
#include "vq4.h"
#include "constants.h"
/*----------------------------------------------------------------*
* vector quantization
*---------------------------------------------------------------*/
void WebRtcIlbcfix_Vq4(
WebRtc_Word16 *Xq, /* quantized vector (Q13) */
WebRtc_Word16 *index,
WebRtc_Word16 *CB, /* codebook in Q13 */
WebRtc_Word16 *X, /* vector to quantize (Q13) */
WebRtc_Word16 n_cb
){
WebRtc_Word16 i, j;
WebRtc_Word16 pos, minindex=0;
WebRtc_Word16 tmp;
WebRtc_Word32 dist, mindist;
pos = 0;
mindist = WEBRTC_SPL_WORD32_MAX; /* start value */
/* Find the codebook with the lowest square distance */
for (j = 0; j < n_cb; j++) {
tmp = X[0] - CB[pos];
dist = WEBRTC_SPL_MUL_16_16(tmp, tmp);
for (i = 1; i < 4; i++) {
tmp = X[i] - CB[pos + i];
dist += WEBRTC_SPL_MUL_16_16(tmp, tmp);
}
if (dist < mindist) {
mindist = dist;
minindex = j;
}
pos += 4;
}
/* Store the quantized codebook and the index */
for (i = 0; i < 4; i++) {
Xq[i] = CB[minindex*4 + i];
}
*index = minindex;
}