hvirtual/mpeg2enc/putvlc.c

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/* putvlc.c, generation of variable length codes                            */

/* Copyright (C) 1996, MPEG Software Simulation Group. All Rights Reserved. */

/*
 * Disclaimer of Warranty
 *
 * These software programs are available to the user without any license fee or
 * royalty on an "as is" basis.  The MPEG Software Simulation Group disclaims
 * any and all warranties, whether express, implied, or statuary, including any
 * implied warranties or merchantability or of fitness for a particular
 * purpose.  In no event shall the copyright-holder be liable for any
 * incidental, punitive, or consequential damages of any kind whatsoever
 * arising from the use of these programs.
 *
 * This disclaimer of warranty extends to the user of these programs and user's
 * customers, employees, agents, transferees, successors, and assigns.
 *
 * The MPEG Software Simulation Group does not represent or warrant that the
 * programs furnished hereunder are free of infringement of any third-party
 * patents.
 *
 * Commercial implementations of MPEG-1 and MPEG-2 video, including shareware,
 * are subject to royalty fees to patent holders.  Many of these patents are
 * general enough such that they are unavoidable regardless of implementation
 * design.
 *
 */

#include <stdio.h>

#include "config.h"
#include "global.h"
#include "vlc.h"

/* generate variable length code for DC coefficient (7.2.1) */
static void putDC(slice_engine_t *engine, sVLCtable *tab, int val)
{
        int absval, size;

        absval = (val < 0) ? -val : val;

        if(absval > dctsatlim)
        {
/* should never happen */
        sprintf(errortext,"DC value out of range (%d)\n",val);
        error(errortext);
        }

/* compute dct_dc_size */
        size = 0;

        while(absval)
        {
        absval >>= 1;
        size++;
        }

//printf("putDC %x %d %d\n", tab[size].code, tab[size].len, size);
//slice_testbits(engine);
/* generate VLC for dct_dc_size (Table B-12 or B-13) */
        slice_putbits(engine, tab[size].code, tab[size].len);
//slice_testbits(engine);

/* append fixed length code (dc_dct_differential) */
        if(size != 0)
        {
        if(val >= 0)
                absval = val;
        else
                absval = val + (1 << size) - 1;
        slice_putbits(engine, absval, size);
        }
//slice_testbits(engine);
}

/* generate variable length code for luminance DC coefficient */
void putDClum(slice_engine_t *engine, int val)
{
    putDC(engine, DClumtab, val);
}

/* generate variable length code for chrominance DC coefficient */
void putDCchrom(slice_engine_t *engine, int val)
{
    putDC(engine, DCchromtab, val);
}

/* generate variable length code for other DCT coefficients (7.2.2) */
void putAC(slice_engine_t *engine, int run, int signed_level, int vlcformat)
{
        int level, len;
        VLCtable *ptab;

        level = (signed_level < 0) ? -signed_level : signed_level; /* abs(signed_level) */

/* make sure run and level are valid */
        if(run < 0 || run > 63 || level == 0 || level > dctsatlim)
        {
        sprintf(errortext,"AC value out of range (run=%d, signed_level=%d)\n",
                run,signed_level);
        error(errortext);
        }

        len = 0;

        if(run < 2 && level < 41)
        {
/* vlcformat selects either of Table B-14 / B-15 */
        if(vlcformat)
                ptab = &dct_code_tab1a[run][level - 1];
        else
                ptab = &dct_code_tab1[run][level - 1];

        len = ptab->len;
        }
        else 
        if(run < 32 && level < 6)
        {
/* vlcformat selects either of Table B-14 / B-15 */
        if(vlcformat)
                ptab = &dct_code_tab2a[run - 2][level - 1];
        else
                ptab = &dct_code_tab2[run - 2][level - 1];

        len = ptab->len;
        }

        if(len != 0) /* a VLC code exists */
        {
        slice_putbits(engine, ptab->code, len);
        slice_putbits(engine, signed_level < 0, 1); /* sign */
        }
        else
        {
/* no VLC for this (run, level) combination: use escape coding (7.2.2.3) */
        slice_putbits(engine, 1l, 6); /* Escape */
        slice_putbits(engine, run, 6); /* 6 bit code for run */
        if(mpeg1)
        {
/* ISO/IEC 11172-2 uses a 8 or 16 bit code */
                if (signed_level > 127)
                        slice_putbits(engine, 0, 8);
                if (signed_level < -127)
                        slice_putbits(engine, 128, 8);
                slice_putbits(engine, signed_level, 8);
        }
        else
        {
/* ISO/IEC 13818-2 uses a 12 bit code, Table B-16 */
                slice_putbits(engine, signed_level, 12);
        }
        }
}

/* generate variable length code for first coefficient
 * of a non-intra block (7.2.2.2) */
void putACfirst(slice_engine_t *engine, int run, int val)
{
        if(run == 0 && (val == 1 || val == -1)) /* these are treated differently */
        slice_putbits(engine, 2 | (val < 0), 2); /* generate '1s' (s=sign), (Table B-14, line 2) */
        else
        putAC(engine, run, val, 0); /* no difference for all others */
}

/* generate variable length code for macroblock_address_increment (6.3.16) */
void putaddrinc(slice_engine_t *engine, int addrinc)
{
        while(addrinc > 33)
        {
        slice_putbits(engine, 0x08, 11); /* macroblock_escape */
        addrinc -= 33;
        }

//printf("putaddrinc %d %d\n", addrinctab[addrinc - 1].code, addrinctab[addrinc - 1].len);
//sleep(1);
        slice_putbits(engine, 
                addrinctab[addrinc - 1].code,
                addrinctab[addrinc - 1].len);
}

/* generate variable length code for macroblock_type (6.3.16.1) */
void putmbtype(slice_engine_t *engine, int pict_type, int mb_type)
{
        slice_putbits(engine, 
                mbtypetab[pict_type - 1][mb_type].code,
        mbtypetab[pict_type - 1][mb_type].len);
}

/* generate variable length code for motion_code (6.3.16.3) */
void putmotioncode(slice_engine_t *engine, int motion_code)
{
        int abscode;

        abscode = (motion_code >= 0) ? motion_code : -motion_code; /* abs(motion_code) */
        slice_putbits(engine, 
                motionvectab[abscode].code, 
                motionvectab[abscode].len);
        if(motion_code!=0)
        slice_putbits(engine, 
                        motion_code < 0,
                        1); /* sign, 0=positive, 1=negative */
}

/* generate variable length code for dmvector[t] (6.3.16.3), Table B-11 */
void putdmv(slice_engine_t *engine, int dmv)
{
  if(dmv == 0)
          slice_putbits(engine, 0, 1);
  else if (dmv>0)
      slice_putbits(engine, 2, 2);
  else
      slice_putbits(engine, 3, 2);
}

/* generate variable length code for coded_block_pattern (6.3.16.4)
 *
 * 4:2:2, 4:4:4 not implemented
 */
void putcbp(slice_engine_t *engine, int cbp)
{
    slice_putbits(engine, cbptable[cbp].code, cbptable[cbp].len);
}

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