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_StateSearch.c
16
17******************************************************************/
18
19#include "defines.h"
20#include "constants.h"
21#include "abs_quant.h"
22
23/*----------------------------------------------------------------*
24 *  encoding of start state
25 *---------------------------------------------------------------*/
26
27void WebRtcIlbcfix_StateSearch(
28    IlbcEncoder *iLBCenc_inst,
29    /* (i) Encoder instance */
30    iLBC_bits *iLBC_encbits,/* (i/o) Encoded bits (output idxForMax
31                               and idxVec, input state_first) */
32    int16_t *residual,   /* (i) target residual vector */
33    int16_t *syntDenum,  /* (i) lpc synthesis filter */
34    int16_t *weightDenum  /* (i) weighting filter denuminator */
35                               ) {
36  size_t k, index;
37  int16_t maxVal;
38  int16_t scale, shift;
39  int32_t maxValsq;
40  int16_t scaleRes;
41  int16_t max;
42  int i;
43  /* Stack based */
44  int16_t numerator[1+LPC_FILTERORDER];
45  int16_t residualLongVec[2*STATE_SHORT_LEN_30MS+LPC_FILTERORDER];
46  int16_t sampleMa[2*STATE_SHORT_LEN_30MS];
47  int16_t *residualLong = &residualLongVec[LPC_FILTERORDER];
48  int16_t *sampleAr = residualLong;
49
50  /* Scale to maximum 12 bits to avoid saturation in circular convolution filter */
51  max = WebRtcSpl_MaxAbsValueW16(residual, iLBCenc_inst->state_short_len);
52  scaleRes = WebRtcSpl_GetSizeInBits(max)-12;
53  scaleRes = WEBRTC_SPL_MAX(0, scaleRes);
54  /* Set up the filter coefficients for the circular convolution */
55  for (i=0; i<LPC_FILTERORDER+1; i++) {
56    numerator[i] = (syntDenum[LPC_FILTERORDER-i]>>scaleRes);
57  }
58
59  /* Copy the residual to a temporary buffer that we can filter
60   * and set the remaining samples to zero.
61   */
62  WEBRTC_SPL_MEMCPY_W16(residualLong, residual, iLBCenc_inst->state_short_len);
63  WebRtcSpl_MemSetW16(residualLong + iLBCenc_inst->state_short_len, 0, iLBCenc_inst->state_short_len);
64
65  /* Run the Zero-Pole filter (Ciurcular convolution) */
66  WebRtcSpl_MemSetW16(residualLongVec, 0, LPC_FILTERORDER);
67  WebRtcSpl_FilterMAFastQ12(residualLong, sampleMa, numerator,
68                            LPC_FILTERORDER + 1,
69                            iLBCenc_inst->state_short_len + LPC_FILTERORDER);
70  WebRtcSpl_MemSetW16(&sampleMa[iLBCenc_inst->state_short_len + LPC_FILTERORDER], 0, iLBCenc_inst->state_short_len - LPC_FILTERORDER);
71
72  WebRtcSpl_FilterARFastQ12(
73      sampleMa, sampleAr,
74      syntDenum, LPC_FILTERORDER+1, 2 * iLBCenc_inst->state_short_len);
75
76  for(k=0;k<iLBCenc_inst->state_short_len;k++){
77    sampleAr[k] += sampleAr[k+iLBCenc_inst->state_short_len];
78  }
79
80  /* Find maximum absolute value in the vector */
81  maxVal=WebRtcSpl_MaxAbsValueW16(sampleAr, iLBCenc_inst->state_short_len);
82
83  /* Find the best index */
84
85  if ((((int32_t)maxVal)<<scaleRes)<23170) {
86    maxValsq=((int32_t)maxVal*maxVal)<<(2+2*scaleRes);
87  } else {
88    maxValsq=(int32_t)WEBRTC_SPL_WORD32_MAX;
89  }
90
91  index=0;
92  for (i=0;i<63;i++) {
93
94    if (maxValsq>=WebRtcIlbcfix_kChooseFrgQuant[i]) {
95      index=i+1;
96    } else {
97      i=63;
98    }
99  }
100  iLBC_encbits->idxForMax=index;
101
102  /* Rescale the vector before quantization */
103  scale=WebRtcIlbcfix_kScale[index];
104
105  if (index<27) { /* scale table is in Q16, fout[] is in Q(-1) and we want the result to be in Q11 */
106    shift=4;
107  } else { /* scale table is in Q21, fout[] is in Q(-1) and we want the result to be in Q11 */
108    shift=9;
109  }
110
111  /* Set up vectors for AbsQuant and rescale it with the scale factor */
112  WebRtcSpl_ScaleVectorWithSat(sampleAr, sampleAr, scale,
113                              iLBCenc_inst->state_short_len, (int16_t)(shift-scaleRes));
114
115  /* Quantize the values in fout[] */
116  WebRtcIlbcfix_AbsQuant(iLBCenc_inst, iLBC_encbits, sampleAr, weightDenum);
117
118  return;
119}
120