ilbc_decode.c

mediastreamer2是开源的网络传输媒体流的库

       unsigned char *bytes,           /* (i) encoded signal bits */
       iLBC_Dec_Inst_t *iLBCdec_inst,  /* (i/o) the decoder state
                                                structure */
       int mode                    /* (i) 0: bad packet, PLC,
                                              1: normal */
   ){
       float data[BLOCKL_MAX];
       float lsfdeq[LPC_FILTERORDER*LPC_N_MAX];
       float PLCresidual[BLOCKL_MAX], PLClpc[LPC_FILTERORDER + 1];
       float zeros[BLOCKL_MAX], one[LPC_FILTERORDER + 1];
       int k, i, start, idxForMax, pos, lastpart, ulp;
       int lag, ilag;
       float cc, maxcc;
       int idxVec[STATE_LEN];
       int check;
       int gain_index[NASUB_MAX*CB_NSTAGES],
           extra_gain_index[CB_NSTAGES];
       int cb_index[CB_NSTAGES*NASUB_MAX], extra_cb_index[CB_NSTAGES];
       int lsf_i[LSF_NSPLIT*LPC_N_MAX];
       int state_first;
       int last_bit;
       unsigned char *pbytes;
       float weightdenum[(LPC_FILTERORDER + 1)*NSUB_MAX];
       int order_plus_one;
       float syntdenum[NSUB_MAX*(LPC_FILTERORDER+1)];
       float decresidual[BLOCKL_MAX];

       if (mode>0) { /* the data are good */

           /* decode data */

           pbytes=bytes;
           pos=0;






           /* Set everything to zero before decoding */

           for (k=0; k<LSF_NSPLIT*LPC_N_MAX; k++) {
               lsf_i[k]=0;
           }
           start=0;
           state_first=0;
           idxForMax=0;
           for (k=0; k<iLBCdec_inst->state_short_len; k++) {
               idxVec[k]=0;
           }
           for (k=0; k<CB_NSTAGES; k++) {
               extra_cb_index[k]=0;
           }
           for (k=0; k<CB_NSTAGES; k++) {
               extra_gain_index[k]=0;
           }
           for (i=0; i<iLBCdec_inst->nasub; i++) {
               for (k=0; k<CB_NSTAGES; k++) {
                   cb_index[i*CB_NSTAGES+k]=0;
               }
           }
           for (i=0; i<iLBCdec_inst->nasub; i++) {
               for (k=0; k<CB_NSTAGES; k++) {
                   gain_index[i*CB_NSTAGES+k]=0;
               }
           }

           /* loop over ULP classes */

           for (ulp=0; ulp<3; ulp++) {

               /* LSF */
               for (k=0; k<LSF_NSPLIT*iLBCdec_inst->lpc_n; k++){
                   unpack( &pbytes, &lastpart,
                       iLBCdec_inst->ULP_inst->lsf_bits[k][ulp], &pos);
                   packcombine(&lsf_i[k], lastpart,
                       iLBCdec_inst->ULP_inst->lsf_bits[k][ulp]);
               }

               /* Start block info */

               unpack( &pbytes, &lastpart,
                   iLBCdec_inst->ULP_inst->start_bits[ulp], &pos);
               packcombine(&start, lastpart,
                   iLBCdec_inst->ULP_inst->start_bits[ulp]);

               unpack( &pbytes, &lastpart,





                   iLBCdec_inst->ULP_inst->startfirst_bits[ulp], &pos);
               packcombine(&state_first, lastpart,
                   iLBCdec_inst->ULP_inst->startfirst_bits[ulp]);

               unpack( &pbytes, &lastpart,
                   iLBCdec_inst->ULP_inst->scale_bits[ulp], &pos);
               packcombine(&idxForMax, lastpart,
                   iLBCdec_inst->ULP_inst->scale_bits[ulp]);

               for (k=0; k<iLBCdec_inst->state_short_len; k++) {
                   unpack( &pbytes, &lastpart,
                       iLBCdec_inst->ULP_inst->state_bits[ulp], &pos);
                   packcombine(idxVec+k, lastpart,
                       iLBCdec_inst->ULP_inst->state_bits[ulp]);
               }

               /* 23/22 (20ms/30ms) sample block */

               for (k=0; k<CB_NSTAGES; k++) {
                   unpack( &pbytes, &lastpart,
                       iLBCdec_inst->ULP_inst->extra_cb_index[k][ulp],
                       &pos);
                   packcombine(extra_cb_index+k, lastpart,
                       iLBCdec_inst->ULP_inst->extra_cb_index[k][ulp]);
               }
               for (k=0; k<CB_NSTAGES; k++) {
                   unpack( &pbytes, &lastpart,
                       iLBCdec_inst->ULP_inst->extra_cb_gain[k][ulp],
                       &pos);
                   packcombine(extra_gain_index+k, lastpart,
                       iLBCdec_inst->ULP_inst->extra_cb_gain[k][ulp]);
               }

               /* The two/four (20ms/30ms) 40 sample sub-blocks */

               for (i=0; i<iLBCdec_inst->nasub; i++) {
                   for (k=0; k<CB_NSTAGES; k++) {
                       unpack( &pbytes, &lastpart,
                       iLBCdec_inst->ULP_inst->cb_index[i][k][ulp],
                           &pos);
                       packcombine(cb_index+i*CB_NSTAGES+k, lastpart,
                       iLBCdec_inst->ULP_inst->cb_index[i][k][ulp]);
                   }
               }

               for (i=0; i<iLBCdec_inst->nasub; i++) {
                   for (k=0; k<CB_NSTAGES; k++) {
                       unpack( &pbytes, &lastpart,





                       iLBCdec_inst->ULP_inst->cb_gain[i][k][ulp],
                           &pos);
                       packcombine(gain_index+i*CB_NSTAGES+k, lastpart,
                           iLBCdec_inst->ULP_inst->cb_gain[i][k][ulp]);
                   }
               }
           }
           /* Extract last bit. If it is 1 this indicates an
              empty/lost frame */
           unpack( &pbytes, &last_bit, 1, &pos);

           /* Check for bit errors or empty/lost frames */
           if (start<1)
               mode = 0;
           if (iLBCdec_inst->mode==20 && start>3)
               mode = 0;
           if (iLBCdec_inst->mode==30 && start>5)
               mode = 0;
           if (last_bit==1)
               mode = 0;

           if (mode==1) { /* No bit errors was detected,
                             continue decoding */

               /* adjust index */
               index_conv_dec(cb_index);

               /* decode the lsf */

               SimplelsfDEQ(lsfdeq, lsf_i, iLBCdec_inst->lpc_n);
               check=LSF_check(lsfdeq, LPC_FILTERORDER,
                   iLBCdec_inst->lpc_n);
               DecoderInterpolateLSF(syntdenum, weightdenum,
                   lsfdeq, LPC_FILTERORDER, iLBCdec_inst);

               Decode(iLBCdec_inst, decresidual, start, idxForMax,
                   idxVec, syntdenum, cb_index, gain_index,
                   extra_cb_index, extra_gain_index,
                   state_first);

               /* preparing the plc for a future loss! */

               doThePLC(PLCresidual, PLClpc, 0, decresidual,
                   syntdenum +
                   (LPC_FILTERORDER + 1)*(iLBCdec_inst->nsub - 1),
                   (*iLBCdec_inst).last_lag, iLBCdec_inst);







               memcpy(decresidual, PLCresidual,
                   iLBCdec_inst->blockl*sizeof(float));
           }

       }

       if (mode == 0) {
           /* the data is bad (either a PLC call
            * was made or a severe bit error was detected)
            */

           /* packet loss conceal */

           memset(zeros, 0, BLOCKL_MAX*sizeof(float));

           one[0] = 1;
           memset(one+1, 0, LPC_FILTERORDER*sizeof(float));

           start=0;

           doThePLC(PLCresidual, PLClpc, 1, zeros, one,
               (*iLBCdec_inst).last_lag, iLBCdec_inst);
           memcpy(decresidual, PLCresidual,
               iLBCdec_inst->blockl*sizeof(float));

           order_plus_one = LPC_FILTERORDER + 1;
           for (i = 0; i < iLBCdec_inst->nsub; i++) {
               memcpy(syntdenum+(i*order_plus_one), PLClpc,
                   order_plus_one*sizeof(float));
           }
       }

       if (iLBCdec_inst->use_enhancer == 1) {

           /* post filtering */

           iLBCdec_inst->last_lag =
               enhancerInterface(data, decresidual, iLBCdec_inst);

           /* synthesis filtering */

           if (iLBCdec_inst->mode==20) {
               /* Enhancer has 40 samples delay */
               i=0;
               syntFilter(data + i*SUBL,
                   iLBCdec_inst->old_syntdenum +
                   (i+iLBCdec_inst->nsub-1)*(LPC_FILTERORDER+1),
                   SUBL, iLBCdec_inst->syntMem);





               for (i=1; i < iLBCdec_inst->nsub; i++) {
                   syntFilter(data + i*SUBL,
                       syntdenum + (i-1)*(LPC_FILTERORDER+1),
                       SUBL, iLBCdec_inst->syntMem);
               }
           } else if (iLBCdec_inst->mode==30) {
               /* Enhancer has 80 samples delay */
               for (i=0; i < 2; i++) {
                   syntFilter(data + i*SUBL,
                       iLBCdec_inst->old_syntdenum +
                       (i+iLBCdec_inst->nsub-2)*(LPC_FILTERORDER+1),
                       SUBL, iLBCdec_inst->syntMem);
               }
               for (i=2; i < iLBCdec_inst->nsub; i++) {
                   syntFilter(data + i*SUBL,
                       syntdenum + (i-2)*(LPC_FILTERORDER+1), SUBL,
                       iLBCdec_inst->syntMem);
               }
           }

       } else {

           /* Find last lag */
           lag = 20;
           maxcc = xCorrCoef(&decresidual[BLOCKL_MAX-ENH_BLOCKL],
               &decresidual[BLOCKL_MAX-ENH_BLOCKL-lag], ENH_BLOCKL);

           for (ilag=21; ilag<120; ilag++) {
               cc = xCorrCoef(&decresidual[BLOCKL_MAX-ENH_BLOCKL],
                   &decresidual[BLOCKL_MAX-ENH_BLOCKL-ilag],
                   ENH_BLOCKL);

               if (cc > maxcc) {
                   maxcc = cc;
                   lag = ilag;
               }
           }
           iLBCdec_inst->last_lag = lag;

           /* copy data and run synthesis filter */

           memcpy(data, decresidual,
               iLBCdec_inst->blockl*sizeof(float));
           for (i=0; i < iLBCdec_inst->nsub; i++) {
               syntFilter(data + i*SUBL,
                   syntdenum + i*(LPC_FILTERORDER+1), SUBL,
                   iLBCdec_inst->syntMem);
           }





       }

       /* high pass filtering on output if desired, otherwise
          copy to out */

       hpOutput(data, iLBCdec_inst->blockl,
                   decblock,iLBCdec_inst->hpomem);

       /* memcpy(decblock,data,iLBCdec_inst->blockl*sizeof(float));*/

       memcpy(iLBCdec_inst->old_syntdenum, syntdenum,

           iLBCdec_inst->nsub*(LPC_FILTERORDER+1)*sizeof(float));

       iLBCdec_inst->prev_enh_pl=0;

       if (mode==0) { /* PLC was used */
           iLBCdec_inst->prev_enh_pl=1;
       }
   }