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_LpcEncode.c
16 
17 ******************************************************************/
18 
19 #include "defines.h"
20 #include "simple_lpc_analysis.h"
21 #include "simple_interpolate_lsf.h"
22 #include "simple_lsf_quant.h"
23 #include "lsf_check.h"
24 #include "constants.h"
25 
26 /*----------------------------------------------------------------*
27  *  lpc encoder
28  *---------------------------------------------------------------*/
29 
WebRtcIlbcfix_LpcEncode(int16_t * syntdenum,int16_t * weightdenum,int16_t * lsf_index,int16_t * data,IlbcEncoder * iLBCenc_inst)30 void WebRtcIlbcfix_LpcEncode(
31     int16_t *syntdenum,  /* (i/o) synthesis filter coefficients
32                                            before/after encoding */
33     int16_t *weightdenum, /* (i/o) weighting denumerator coefficients
34                                    before/after encoding */
35     int16_t *lsf_index,  /* (o) lsf quantization index */
36     int16_t *data,   /* (i) Speech to do LPC analysis on */
37     IlbcEncoder *iLBCenc_inst
38     /* (i/o) the encoder state structure */
39                               ) {
40   /* Stack based */
41   int16_t lsf[LPC_FILTERORDER * LPC_N_MAX];
42   int16_t lsfdeq[LPC_FILTERORDER * LPC_N_MAX];
43 
44   /* Calculate LSF's from the input speech */
45   WebRtcIlbcfix_SimpleLpcAnalysis(lsf, data, iLBCenc_inst);
46 
47   /* Quantize the LSF's */
48   WebRtcIlbcfix_SimpleLsfQ(lsfdeq, lsf_index, lsf, iLBCenc_inst->lpc_n);
49 
50   /* Stableize the LSF's if needed */
51   WebRtcIlbcfix_LsfCheck(lsfdeq, LPC_FILTERORDER, iLBCenc_inst->lpc_n);
52 
53   /* Calculate the synthesis and weighting filter coefficients from
54      the optimal LSF and the dequantized LSF */
55   WebRtcIlbcfix_SimpleInterpolateLsf(syntdenum, weightdenum,
56                                      lsf, lsfdeq, iLBCenc_inst->lsfold,
57                                      iLBCenc_inst->lsfdeqold, LPC_FILTERORDER, iLBCenc_inst);
58 
59   return;
60 }
61