getvlc.cc

ac3的解码程序

#include "all.hh"
#include "getvlc.hh"

/* private prototypes */
inline int getIMBtype(void);
inline int getPMBtype(void);
inline int getBMBtype(void);
inline int getDMBtype(void);
inline int getspIMBtype(void);
inline int getspPMBtype(void);
inline int getspBMBtype(void);
inline int getSNRMBtype(void);


int getMBtype(){
  if (ld->scalable_mode==SC_SNR) return getSNRMBtype();
  else{
    switch (pict_type){
    case I_TYPE: return ld->pict_scal ? getspIMBtype() : getIMBtype();
    case P_TYPE: return ld->pict_scal ? getspPMBtype() : getPMBtype();
    case B_TYPE: return ld->pict_scal ? getspBMBtype() : getBMBtype();
    case D_TYPE: return getDMBtype();
    default: if (!quiet) { msg("getMBtype: unknown coding type");dec2hex(pict_type);}
      /* MPEG-1 only, not implemented */
    }
  }

  return 0;
}


inline int getIMBtype(){
#ifdef TRACE
  if (trace) printf("mb_type(I) ");
#endif

  if (vs->getbits(1)){
#ifdef TRACE
    if (trace) printf("(1): Intra (1)\n");
#endif
    return 1;
  }

  if (!vs->getbits(1)){
    if (!quiet) fprintf(stderr,"Invalid macroblock_type code (getIMBtype)\n");
    fault = 1;
  }

#ifdef TRACE
  if (trace) printf("(01): Intra, Quant (17)\n");
#endif

  return 17;
}

#ifdef TRACE
static char *MBdescr[]={
  "",                  "Intra",        "No MC, Coded",         "",
  "Bwd, Not Coded",    "",             "Bwd, Coded",           "",
  "Fwd, Not Coded",    "",             "Fwd, Coded",           "",
  "Interp, Not Coded", "",             "Interp, Coded",        "",
  "",                  "Intra, Quant", "No MC, Coded, Quant",  "",
  "",                  "",             "Bwd, Coded, Quant",    "",
  "",                  "",             "Fwd, Coded, Quant",    "",
  "",                  "",             "Interp, Coded, Quant", ""
};
#endif


inline int getPMBtype(){
  int code;

#ifdef TRACE
  if (trace) printf("mb_type(P) (");
#endif

  if ((code = vs->showbits(6))>=8){
    code >>= 3;
    vs->flushbits(PMBtab0[code].len);
#ifdef TRACE
    if (trace){
      printbits(code,3,PMBtab0[code].len);
      printf("): %s (%d)\n",MBdescr[PMBtab0[code].val],PMBtab0[code].val);
    }
#endif
    return PMBtab0[code].val;
  }

  if (code==0){
    if (!quiet) fprintf(stderr,"Invalid macroblock_type code (getPMBtype)\n");
    fault = 1;
    return 0;
  }

  vs->flushbits(PMBtab1[code].len);

#ifdef TRACE
  if (trace){
    printbits(code,6,PMBtab1[code].len);
    printf("): %s (%d)\n",MBdescr[PMBtab1[code].val],PMBtab1[code].val);
  }
#endif

  return PMBtab1[code].val;
}


inline int getBMBtype(){
  int code;

#ifdef TRACE
  if (trace) printf("mb_type(B) (");
#endif

  if ((code = vs->showbits(6))>=8){
    code >>= 2;
    vs->flushbits(BMBtab0[code].len);

#ifdef TRACE
    if (trace){
      printbits(code,4,BMBtab0[code].len);
      printf("): %s (%d)\n",MBdescr[BMBtab0[code].val],BMBtab0[code].val);
    }
#endif

    return BMBtab0[code].val;
  }

  if (code==0){
    if (!quiet) fprintf(stderr,"Invalid macroblock_type code (getBMBtype)\n");
    fault = 1;
    return 0;
  }

  vs->flushbits(BMBtab1[code].len);

#ifdef TRACE
  if (trace){
    printbits(code,6,BMBtab1[code].len);
    printf("): %s (%d)\n",MBdescr[BMBtab1[code].val],BMBtab1[code].val);
  }
#endif

  return BMBtab1[code].val;
}


inline int getDMBtype(){
  if (!vs->getbits(1)){
    if (!quiet) fprintf(stderr,"Invalid macroblock_type code (getDMBtype)\n");
    fault=1;
  }

  return 1;
}


/* macroblock_type for pictures with spatial scalability */
inline int getspIMBtype(){
  int code;

#ifdef TRACE
  if (trace)
    printf("mb_type(I,spat) (");
#endif

  code = vs->showbits(4);

  if (code==0){
    if (!quiet) fprintf(stderr,"Invalid macroblock_type code (getspIMBtype)\n");
    fault = 1;
    return 0;
  }

#ifdef TRACE
  if (trace){
    printbits(code,4,spIMBtab[code].len);
    printf("): %02x\n",spIMBtab[code].val);
  }
#endif

  vs->flushbits(spIMBtab[code].len);
  return spIMBtab[code].val;
}


inline int getspPMBtype(){
#ifdef TRACE
  if (trace) printf("mb_type(P,spat) (");
#endif
  int code = vs->showbits(7);

  if (code<2){
    if (!quiet) fprintf(stderr,"Invalid macroblock_type code (getspPMBtype)\n");
    fault = 1;
    return 0;
  }

  if (code>=16){
    code >>= 3;
    vs->flushbits(spPMBtab0[code].len);

#ifdef TRACE
    if (trace){
      printbits(code,4,spPMBtab0[code].len);
      printf("): %02x\n",spPMBtab0[code].val);
    }
#endif

    return spPMBtab0[code].val;
  }

  vs->flushbits(spPMBtab1[code].len);

#ifdef TRACE
  if (trace){
    printbits(code,7,spPMBtab1[code].len);
    printf("): %02x\n",spPMBtab1[code].val);
  }
#endif

  return spPMBtab1[code].val;
}


inline int getspBMBtype(){
  VLCtab *p;
#ifdef TRACE
  if (trace) printf("mb_type(B,spat) (");
#endif
  int code = vs->showbits(9);

  if (code>=64)      p = &spBMBtab0[(code>>5)-2];
  else if (code>=16) p = &spBMBtab1[(code>>2)-4];
  else if (code>=8)  p = &spBMBtab2[code-8];
  else {
    if (!quiet) fprintf(stderr,"Invalid macroblock_type code (getspBMBtype)\n");
    fault = 1;
    return 0;
  }

  vs->flushbits(p->len);

#ifdef TRACE
  if (trace){
    printbits(code,9,p->len);
    printf("): %02x\n",p->val);
  }
#endif

  return p->val;
}


inline int getSNRMBtype(){
  int code = vs->showbits(3);

  if (code==0){
    if (!quiet) fprintf(stderr,"Invalid macroblock_type code (getSNSRMBtype)\n");
    fault = 1;
    return 0;
  }

  vs->flushbits(SNRMBtab[code].len);
  return SNRMBtab[code].val;
}


int getMV(){
  int code;

#ifdef TRACE
  if (trace) printf("motion_code (");
#endif

  if (vs->getbits(1)){
#ifdef TRACE
    if (trace) printf("0): 0\n");
#endif
    return 0;
  }

  if ((code = vs->showbits(9))>=64){
    code >>= 6;
    vs->flushbits(MVtab0[code].len);

#ifdef TRACE
    if (trace){
      printbits(code,3,MVtab0[code].len);
      printf("%d): %d\n",
        vs->showbits(1),vs->showbits(1)?-MVtab0[code].val:MVtab0[code].val);
    }
#endif

    return vs->getbits(1)?-MVtab0[code].val:MVtab0[code].val;
  }

  if (code>=24){
    code >>= 3;
    vs->flushbits(MVtab1[code].len);

#ifdef TRACE
    if (trace){
      printbits(code,6,MVtab1[code].len);
      printf("%d): %d\n",
        vs->showbits(1),vs->showbits(1)?-MVtab1[code].val:MVtab1[code].val);
    }
#endif

    return vs->getbits(1)?-MVtab1[code].val:MVtab1[code].val;
  }

  if ((code-=12)<0){
    if (!quiet) fprintf(stderr,"Invalid motion_vector code\n");
    fault=1;
    return 0;
  }

  vs->flushbits(MVtab2[code].len);

#ifdef TRACE
  if (trace){
    printbits(code+12,9,MVtab2[code].len);
    printf("%d): %d\n",
      vs->showbits(1),vs->showbits(1)?-MVtab2[code].val:MVtab2[code].val);
  }
#endif

  return vs->getbits(1) ? -MVtab2[code].val : MVtab2[code].val;
}


/* get differential motion vector (for dual prime prediction) */

int getDMV(){
#ifdef TRACE
  if (trace) printf("dmvector (");
#endif

  if (vs->getbits(1)){
#ifdef TRACE
    if (trace) printf(vs->showbits(1) ? "11): -1\n" : "10): 1\n");
#endif
    return vs->getbits(1) ? -1 : 1;
  }
  else {
#ifdef TRACE
    if (trace) printf("0): 0\n");
#endif
    return 0;
  }
}


int getCBP(){
  int code;

#ifdef TRACE
  if (trace) printf("coded_block_pattern_420 (");
#endif

  if ((code = vs->showbits(9))>=128){
    code >>= 4;
    vs->flushbits(CBPtab0[code].len);

#ifdef TRACE
    if (trace){
      printbits(code,5,CBPtab0[code].len);
      printf("): ");
      printbits(CBPtab0[code].val,6,6);
      printf(" (%d)\n",CBPtab0[code].val);
    }
#endif

    return CBPtab0[code].val;
  }

  if (code>=8){
    code >>= 1;
    vs->flushbits(CBPtab1[code].len);

#ifdef TRACE
    if (trace){
      printbits(code,8,CBPtab1[code].len);
      printf("): ");
      printbits(CBPtab1[code].val,6,6);
      printf(" (%d)\n",CBPtab1[code].val);
    }
#endif

    return CBPtab1[code].val;
  }

  if (code<1){
    if (!quiet) fprintf(stderr,"Invalid coded_block_pattern code\n");
    fault = 1;
    return 0;
  }

  vs->flushbits(CBPtab2[code].len);

#ifdef TRACE
  if (trace){
    printbits(code,9,CBPtab2[code].len);
    printf("): ");
    printbits(CBPtab2[code].val,6,6);
    printf(" (%d)\n",CBPtab2[code].val);
  }
#endif

  return CBPtab2[code].val;
}


int getMBA(){
  int code, val;

#ifdef TRACE
  if (trace) printf("macroblock_address_increment (");
#endif

  val=0;

  while ((code = vs->showbits(11))<24){
    if (code!=15){     /* if not macroblock_stuffing */
      if (code==8){    /* if macroblock_escape */
#ifdef TRACE
        if (trace) printf("00000001000 ");
#endif
        val+= 33;
      }
      else {
        if (!quiet) fprintf(stderr,"Invalid macroblock_address_increment code\n");

        fault = 1;
        return 1;
      }
    }
#ifdef TRACE
    else if (trace) printf("00000001111 ");
#endif

    vs->flushbits(11);
  }

  if (code>=1024){
    vs->flushbits(1);
#ifdef TRACE
    if (trace) printf("1): %d\n",val+1);
#endif
    return val + 1;
  }

  if (code>=128){
    code >>= 6;
    vs->flushbits(MBAtab1[code].len);

#ifdef TRACE
    if (trace){
      printbits(code,5,MBAtab1[code].len);
      printf("): %d\n",val+MBAtab1[code].val);
    }
#endif

    return val + MBAtab1[code].val;
  }

  code-= 24;
  vs->flushbits(MBAtab2[code].len);

#ifdef TRACE
  if (trace){
    printbits(code+24,11,MBAtab2[code].len);
    printf("): %d\n",val+MBAtab2[code].val);
  }
#endif

  return val + MBAtab2[code].val;
}


int getDClum(){
  int code, size, val;

#ifdef TRACE
  if (trace) printf("dct_dc_size_luminance: (");
#endif

  /* decode length */
  code = vs->showbits(5);

  if (code<31){
    size = DClumtab0[code].val;
    vs->flushbits(DClumtab0[code].len);
#ifdef TRACE
    if (trace){
      printbits(code,5,DClumtab0[code].len);
      printf("): %d",size);
    }
#endif
  }
  else {
    code = vs->showbits(9) - 0x1f0;
    size = DClumtab1[code].val;
    vs->flushbits(DClumtab1[code].len);

#ifdef TRACE
    if (trace){
      printbits(code+0x1f0,9,DClumtab1[code].len);
      printf("): %d",size);
    }
#endif
  }

#ifdef TRACE
  if (trace) printf(", dct_dc_differential (");
#endif

  if (size==0) val = 0;
  else {
    val = vs->getbits(size);
#ifdef TRACE
    if (trace) printbits(val,size,size);
#endif
    if ((val & (1<<(size-1)))==0)  val-= (1<<size) - 1;
  }

#ifdef TRACE
  if (trace) printf("): %d\n",val);
#endif

  return val;
}


int getDCchrom(){
  int code, size, val;

#ifdef TRACE
  if (trace) printf("dct_dc_size_chrominance: (");
#endif

  /* decode length */
  code = vs->showbits(5);

  if (code<31){
    size = DCchromtab0[code].val;
    vs->flushbits(DCchromtab0[code].len);

#ifdef TRACE
    if (trace){
      printbits(code,5,DCchromtab0[code].len);
      printf("): %d",size);
    }
#endif
  }
  else {
    code = vs->showbits(10) - 0x3e0;
    size = DCchromtab1[code].val;
    vs->flushbits(DCchromtab1[code].len);

#ifdef TRACE
    if (trace){
      printbits(code+0x3e0,10,DCchromtab1[code].len);
      printf("): %d",size);
    }
#endif
  }

#ifdef TRACE
  if (trace) printf(", dct_dc_differential (");
#endif

  if (size==0) val = 0;
  else {
    val = vs->getbits(size);
#ifdef TRACE
    if (trace) printbits(val,size,size);
#endif
    if ((val & (1<<(size-1)))==0) val-= (1<<size) - 1;
  }

#ifdef TRACE
  if (trace) printf("): %d\n",val);
#endif

  return val;
}