dtx_dec.c

这是一个平台无关的标准C的AMR解码库

                        L_shl(L_deposit_l(st->log_en_adjust), 5));  move32();
       
   log_en_int_e = extract_h(L_log_en_int);                    move16();
   move16();
   log_en_int_m = extract_l(L_shr(L_sub(L_log_en_int, 
                                        L_deposit_h(log_en_int_e)), 1));
   level = extract_l(Pow2(log_en_int_e, log_en_int_m)); /* Q4 */ move16();
   
   for (i = 0; i < 4; i++)
   {             
      /* Compute innovation vector */
      build_CN_code(&st->L_pn_seed_rx, ex);
      for (j = 0; j < L_SUBFR; j++)
      {
         ex[j] = mult(level, ex[j]);                                move16();
      }
      /* Synthesize */
      Syn_filt(acoeff_variab, ex, &synth[i * L_SUBFR], L_SUBFR, 
               mem_syn, 1);
      
   } /* next i */
   
   /* reset codebook averaging variables */ 
   averState->hangVar = 20;                                         move16();
   averState->hangCount = 0;                                        move16();
    
   test();
   if (sub(new_state, DTX_MUTE) == 0)
   {
      /* mute comfort noise as it has been quite a long time since  
       * last SID update  was performed                            */
      
      tmp_int_length = st->since_last_sid;                          move16();
      test();
      if (sub(tmp_int_length, 32) > 0)
      {
         tmp_int_length = 32;                                       move16();
      }
      
      /* safety guard against division by zero */
      test();
      if(tmp_int_length <= 0) {
         tmp_int_length = 8;                                       move16();
      }      
      
      move16();
      st->true_sid_period_inv = div_s(1 << 10, shl(tmp_int_length, 10)); 

      st->since_last_sid = 0;                                       move16();
      Copy(st->lsp, st->lsp_old, M);
      st->old_log_en = st->log_en;                                  move16();
      /* subtract 1/8 in Q11 i.e -6/8 dB */
      st->log_en = sub(st->log_en, 256);                            move16();  
   }

   /* reset interpolation length timer 
    * if data has been updated.        */
   test(); test(); test(); test();
   if ((st->sid_frame != 0) && 
       ((st->valid_data != 0) || 
        ((st->valid_data == 0) &&  (st->dtxHangoverAdded) != 0))) 
   {
      st->since_last_sid =  0;                                      move16();
      st->data_updated = 1;                                         move16();
   }
         
   return 0;
}

void dtx_dec_activity_update(dtx_decState *st,
                             Word16 lsf[],
                             Word16 frame[])
{
   Word16 i;

   Word32 L_frame_en;
   Word16 log_en_e, log_en_m, log_en;

   /* update lsp history */
   st->lsf_hist_ptr = add(st->lsf_hist_ptr,M);                     move16();
   test();
   if (sub(st->lsf_hist_ptr, 80) == 0)
   {
      st->lsf_hist_ptr = 0;                                        move16();
   }
   Copy(lsf, &st->lsf_hist[st->lsf_hist_ptr], M); 

   /* compute log energy based on frame energy */
   L_frame_en = 0;     /* Q0 */                                    move32();
   for (i=0; i < L_FRAME; i++)
   {
      L_frame_en = L_mac(L_frame_en, frame[i], frame[i]); 
   }
   Log2(L_frame_en, &log_en_e, &log_en_m);
   
   /* convert exponent and mantissa to Word16 Q10 */
   log_en = shl(log_en_e, 10);  /* Q10 */                          
   log_en = add(log_en, shr(log_en_m, 15-10));                      
   
   /* divide with L_FRAME i.e subtract with log2(L_FRAME) = 7.32193 */
   log_en = sub(log_en, 7497+1024);                                
   
   /* insert into log energy buffer, no division by two as  *
    * log_en in decoder is Q11                              */
   st->log_en_hist_ptr = add(st->log_en_hist_ptr, 1);
   test();
   if (sub(st->log_en_hist_ptr, DTX_HIST_SIZE) == 0)
   {
      st->log_en_hist_ptr = 0;                                     move16();
   }
   st->log_en_hist[st->log_en_hist_ptr] = log_en; /* Q11 */        move16();
}

/*   
     Table of new SPD synthesis states 
     
                           |     previous SPD_synthesis_state
     Incoming              |  
     frame_type            | SPEECH       | DTX           | DTX_MUTE   
     ---------------------------------------------------------------
     RX_SPEECH_GOOD ,      |              |               |
     RX_SPEECH_PR_DEGRADED | SPEECH       | SPEECH        | SPEECH 
     ----------------------------------------------------------------       
     RX_SPEECH_BAD,        | SPEECH       | DTX           | DTX_MUTE
     ----------------------------------------------------------------
     RX_SID_FIRST,         | DTX          | DTX/(DTX_MUTE)| DTX_MUTE  
     ----------------------------------------------------------------
     RX_SID_UPDATE,        | DTX          | DTX           | DTX
     ----------------------------------------------------------------
     RX_SID_BAD,           | DTX          | DTX/(DTX_MUTE)| DTX_MUTE
     ----------------------------------------------------------------
     RX_NO_DATA            | SPEECH       | DTX/(DTX_MUTE)| DTX_MUTE
                           |(class2 garb.)|               |
     ----------------------------------------------------------------
     RX_ONSET              | SPEECH       | DTX/(DTX_MUTE)| DTX_MUTE
                           |(class2 garb.)|               |
     ----------------------------------------------------------------
*/

enum DTXStateType rx_dtx_handler(
                      dtx_decState *st,           /* i/o : State struct     */
                      enum RXFrameType frame_type /* i   : Frame type       */ 
                      )
{
   enum DTXStateType newState;
   enum DTXStateType encState;

   /* DTX if SID frame or previously in DTX{_MUTE} and (NO_RX OR BAD_SPEECH) */
   test(); test(); test();
   test(); test(); test();
   test(); test();   
   if ((sub(frame_type, RX_SID_FIRST) == 0)   ||
       (sub(frame_type, RX_SID_UPDATE) == 0)  ||
       (sub(frame_type, RX_SID_BAD) == 0)     ||
       (((sub(st->dtxGlobalState, DTX) == 0) ||
         (sub(st->dtxGlobalState, DTX_MUTE) == 0)) && 
        ((sub(frame_type, RX_NO_DATA) == 0) ||
         (sub(frame_type, RX_SPEECH_BAD) == 0) || 
         (sub(frame_type, RX_ONSET) == 0))))
   {
      newState = DTX;                                              move16();

      /* stay in mute for these input types */
      test(); test(); test(); test(); test();
      if ((sub(st->dtxGlobalState, DTX_MUTE) == 0) &&
          ((sub(frame_type, RX_SID_BAD) == 0) ||
           (sub(frame_type, RX_SID_FIRST) ==  0) ||
           (sub(frame_type, RX_ONSET) ==  0) ||
           (sub(frame_type, RX_NO_DATA) == 0)))
      {
         newState = DTX_MUTE;                                      move16();
      }

      /* evaluate if noise parameters are too old                     */
      /* since_last_sid is reset when CN parameters have been updated */
      st->since_last_sid = add(st->since_last_sid, 1);             move16();

      /* no update of sid parameters in DTX for a long while */
      /* Due to the delayed update of  st->since_last_sid counter
         SID_UPDATE frames need to be handled separately to avoid
         entering DTX_MUTE for late SID_UPDATE frames
         */
      test(); test(); logic16();
      if((sub(frame_type, RX_SID_UPDATE) != 0) &&
         (sub(st->since_last_sid, DTX_MAX_EMPTY_THRESH) > 0))
      {
         newState = DTX_MUTE;                                      move16();
      }
   }
   else 
   {
      newState = SPEECH;                                           move16();
      st->since_last_sid = 0;                                      move16();
   }
   
   /* 
      reset the decAnaElapsed Counter when receiving CNI data the first  
      time, to robustify counter missmatch after handover
      this might delay the bwd CNI analysis in the new decoder slightly.
   */    
   test(); test();
   if ((st->data_updated == 0) &&
       (sub(frame_type, RX_SID_UPDATE) == 0))
   {
      st->decAnaElapsedCount = 0;                                  move16();
   }

   /* update the SPE-SPD DTX hangover synchronization */
   /* to know when SPE has added dtx hangover         */
   st->decAnaElapsedCount = add(st->decAnaElapsedCount, 1);        move16();
   st->dtxHangoverAdded = 0;                                       move16();
   
   test(); test(); test(); test(); test();
   if ((sub(frame_type, RX_SID_FIRST) == 0)  ||
       (sub(frame_type, RX_SID_UPDATE) == 0) ||
       (sub(frame_type, RX_SID_BAD) == 0)    ||
       (sub(frame_type, RX_ONSET) == 0)      ||
       (sub(frame_type, RX_NO_DATA) == 0))
   {
      encState = DTX;                                              move16();
      
      /*         
         In frame errors simulations RX_NO_DATA may occasionally mean that
         a speech packet was probably sent by the encoder,
         the assumed _encoder_ state should be SPEECH in such cases.
      */
      
      test(); logic16(); 
      if((sub(frame_type, RX_NO_DATA) == 0) &&
         (sub(newState, SPEECH) == 0)) 
      {
         encState = SPEECH;                                       move16();
      }
      
      
      /* Note on RX_ONSET operation differing from RX_NO_DATA operation:
         If a  RX_ONSET is received in the decoder (by "accident")
         it is still most likely that the encoder  state
         for the "ONSET frame" was DTX.
      */      
   }
   else 
   {
      encState = SPEECH;                                           move16();
   }
 
   test();
   if (sub(encState, SPEECH) == 0)
   {
      st->dtxHangoverCount = DTX_HANG_CONST;                       move16();
   }
   else
   {
      test();
      if (sub(st->decAnaElapsedCount, DTX_ELAPSED_FRAMES_THRESH) > 0)
      {
         st->dtxHangoverAdded = 1;                                 move16();
         st->decAnaElapsedCount = 0;                               move16();
         st->dtxHangoverCount = 0;                                 move16();
      }
      else if (test(), st->dtxHangoverCount == 0)
      {
         st->decAnaElapsedCount = 0;                               move16();
      }
      else
      {
         st->dtxHangoverCount = sub(st->dtxHangoverCount, 1);      move16();
      }
   }
   
   if (sub(newState, SPEECH) != 0)
   {
      /* DTX or DTX_MUTE
       * CN data is not in a first SID, first SIDs are marked as SID_BAD 
       *  but will do backwards analysis if a hangover period has been added
       *  according to the state machine above 
       */
      
      st->sid_frame = 0;                                           move16();
      st->valid_data = 0;                                          move16();
            
      test(); 
      if (sub(frame_type, RX_SID_FIRST) == 0)
      {
         st->sid_frame = 1;                                        move16();
      }
      else if (test(), sub(frame_type, RX_SID_UPDATE) == 0)
      {
         st->sid_frame = 1;                                        move16();
         st->valid_data = 1;                                       move16();
      }
      else if (test(), sub(frame_type, RX_SID_BAD) == 0)
      {
         st->sid_frame = 1;                                        move16();
         st->dtxHangoverAdded = 0; /* use old data */              move16();
      } 
   }

   return newState; 
   /* newState is used by both SPEECH AND DTX synthesis routines */ 
}