1 /* 2 * Copyright (c) 2011 The WebRTC project authors. All Rights Reserved. 3 * 4 * Use of this source code is governed by a BSD-style license 5 * that can be found in the LICENSE file in the root of the source 6 * tree. An additional intellectual property rights grant can be found 7 * in the file PATENTS. All contributing project authors may 8 * be found in the AUTHORS file in the root of the source tree. 9 */ 10 11 /****************************************************************** 12 13 iLBC Speech Coder ANSI-C Source Code 14 15 WebRtcIlbcfix_SimpleLsfDeQ.c 16 17 ******************************************************************/ 18 19 #include "defines.h" 20 #include "constants.h" 21 22 /*----------------------------------------------------------------* 23 * obtain dequantized lsf coefficients from quantization index 24 *---------------------------------------------------------------*/ 25 26 void WebRtcIlbcfix_SimpleLsfDeQ( 27 int16_t *lsfdeq, /* (o) dequantized lsf coefficients */ 28 int16_t *index, /* (i) quantization index */ 29 int16_t lpc_n /* (i) number of LPCs */ 30 ){ 31 int i, j, pos, cb_pos; 32 33 /* decode first LSF */ 34 35 pos = 0; 36 cb_pos = 0; 37 for (i = 0; i < LSF_NSPLIT; i++) { 38 for (j = 0; j < WebRtcIlbcfix_kLsfDimCb[i]; j++) { 39 lsfdeq[pos + j] = WebRtcIlbcfix_kLsfCb[cb_pos + j + index[i] * 40 WebRtcIlbcfix_kLsfDimCb[i]]; 41 } 42 pos += WebRtcIlbcfix_kLsfDimCb[i]; 43 cb_pos += WebRtcIlbcfix_kLsfSizeCb[i] * WebRtcIlbcfix_kLsfDimCb[i]; 44 } 45 46 if (lpc_n>1) { 47 /* decode last LSF */ 48 pos = 0; 49 cb_pos = 0; 50 for (i = 0; i < LSF_NSPLIT; i++) { 51 for (j = 0; j < WebRtcIlbcfix_kLsfDimCb[i]; j++) { 52 lsfdeq[LPC_FILTERORDER + pos + j] = WebRtcIlbcfix_kLsfCb[ 53 cb_pos + index[LSF_NSPLIT + i] * WebRtcIlbcfix_kLsfDimCb[i] + j]; 54 } 55 pos += WebRtcIlbcfix_kLsfDimCb[i]; 56 cb_pos += WebRtcIlbcfix_kLsfSizeCb[i] * WebRtcIlbcfix_kLsfDimCb[i]; 57 } 58 } 59 return; 60 } 61
