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      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 
     27 void 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