msmpeg4.c

Trolltech公司发布的图形界面操作系统。可在qt-embedded-2.3.10平台上编译为嵌入式图形界面操作系统。

                    }
                }else if (s->h263_aic_dir==2) {
                    if(n==0){
                        pred= a;
                        *dir_ptr = 0;
                    }else{
                        pred= c;
                        *dir_ptr = 1;
                    }
                } else {
                    pred= c;
                    *dir_ptr = 1;
                }
            }
        }else{
            if (abs(a - b) < abs(b - c)) {
                pred = c;
                *dir_ptr = 1;
            } else {
                pred = a;
                *dir_ptr = 0;
            }
        }
    }else{
        if (abs(a - b) <= abs(b - c)) {
            pred = c;
            *dir_ptr = 1;
        } else {
            pred = a;
            *dir_ptr = 0;
        }
    }

    /* update predictor */
    *dc_val_ptr = &dc_val[0];
    return pred;
}

#define DC_MAX 119

static void msmpeg4_encode_dc(MpegEncContext * s, int level, int n, int *dir_ptr)
{
    int sign, code;
    int pred;

    if(s->msmpeg4_version==1){
        int32_t *dc_val;
        pred = msmpeg4v1_pred_dc(s, n, &dc_val);
        
        /* update predictor */
        *dc_val= level;
    }else{
        uint16_t *dc_val;
        pred = msmpeg4_pred_dc(s, n, &dc_val, dir_ptr);

        /* update predictor */
        if (n < 4) {
            *dc_val = level * s->y_dc_scale;
        } else {
            *dc_val = level * s->c_dc_scale;
        }
    }

    /* do the prediction */
    level -= pred;

    if(s->msmpeg4_version<=2){
        if (n < 4) {
            put_bits(&s->pb, 
                     v2_dc_lum_table[level+256][1],
                     v2_dc_lum_table[level+256][0]);
        }else{
            put_bits(&s->pb, 
                     v2_dc_chroma_table[level+256][1],
                     v2_dc_chroma_table[level+256][0]);
        }
    }else{
        sign = 0;
        if (level < 0) {
            level = -level;
            sign = 1;
        }
        code = level;
        if (code > DC_MAX) 
            code = DC_MAX;

        if (s->dc_table_index == 0) {
            if (n < 4) {
                put_bits(&s->pb, table0_dc_lum[code][1], table0_dc_lum[code][0]);
            } else {
                put_bits(&s->pb, table0_dc_chroma[code][1], table0_dc_chroma[code][0]);
            }
        } else {
            if (n < 4) {
                put_bits(&s->pb, table1_dc_lum[code][1], table1_dc_lum[code][0]);
            } else {
                put_bits(&s->pb, table1_dc_chroma[code][1], table1_dc_chroma[code][0]);
            }
        }
            
        if (code == DC_MAX)
            put_bits(&s->pb, 8, level);
            
        if (level != 0) {
            put_bits(&s->pb, 1, sign);
        }
    }
}

/* Encoding of a block. Very similar to MPEG4 except for a different
   escape coding (same as H263) and more vlc tables.
 */
static inline void msmpeg4_encode_block(MpegEncContext * s, DCTELEM * block, int n)
{
    int level, run, last, i, j, last_index;
    int last_non_zero, sign, slevel;
    int code, run_diff, dc_pred_dir;
    const RLTable *rl;
    const uint8_t *scantable;

    if (s->mb_intra) {
        set_stat(ST_DC);
        msmpeg4_encode_dc(s, block[0], n, &dc_pred_dir);
        i = 1;
        if (n < 4) {
            rl = &rl_table[s->rl_table_index];
        } else {
            rl = &rl_table[3 + s->rl_chroma_table_index];
        }
        run_diff = 0;
        scantable= s->intra_scantable.permutated;
        set_stat(ST_INTRA_AC);
    } else {
        i = 0;
        rl = &rl_table[3 + s->rl_table_index];
        if(s->msmpeg4_version<=2)
            run_diff = 0;
        else
            run_diff = 1;
        scantable= s->inter_scantable.permutated;
        set_stat(ST_INTER_AC);
    }

    /* recalculate block_last_index for M$ wmv1 */
    if(s->msmpeg4_version>=4 && s->block_last_index[n]>0){
        for(last_index=63; last_index>=0; last_index--){
            if(block[scantable[last_index]]) break;
        }
        s->block_last_index[n]= last_index;
    }else
        last_index = s->block_last_index[n];
    /* AC coefs */
    last_non_zero = i - 1;
    for (; i <= last_index; i++) {
	j = scantable[i];
	level = block[j];
	if (level) {
	    run = i - last_non_zero - 1;
	    last = (i == last_index);
	    sign = 0;
	    slevel = level;
	    if (level < 0) {
		sign = 1;
		level = -level;
	    }

            if(level<=MAX_LEVEL && run<=MAX_RUN){
                s->ac_stats[s->mb_intra][n>3][level][run][last]++;
            }
#if 0
else
    s->ac_stats[s->mb_intra][n>3][40][63][0]++; //esc3 like
#endif
            code = get_rl_index(rl, last, run, level);
            put_bits(&s->pb, rl->table_vlc[code][1], rl->table_vlc[code][0]);
            if (code == rl->n) {
                int level1, run1;

                level1 = level - rl->max_level[last][run];
                if (level1 < 1) 
                    goto esc2;
                code = get_rl_index(rl, last, run, level1);
                if (code == rl->n) {
                esc2:
                    put_bits(&s->pb, 1, 0);
                    if (level > MAX_LEVEL)
                        goto esc3;
                    run1 = run - rl->max_run[last][level] - run_diff;
                    if (run1 < 0)
                        goto esc3;
                    code = get_rl_index(rl, last, run1, level);
                    if (code == rl->n) {
                    esc3:
                        /* third escape */
                        put_bits(&s->pb, 1, 0);
                        put_bits(&s->pb, 1, last);
                        if(s->msmpeg4_version>=4){
                            if(s->esc3_level_length==0){
                                s->esc3_level_length=8;
                                s->esc3_run_length= 6;
                                if(s->qscale<8)
                                    put_bits(&s->pb, 6, 3);
                                else
                                    put_bits(&s->pb, 8, 3);
                            }
                            put_bits(&s->pb, s->esc3_run_length, run);
                            put_bits(&s->pb, 1, sign);
                            put_bits(&s->pb, s->esc3_level_length, level);
                        }else{
                            put_bits(&s->pb, 6, run);
                            put_bits(&s->pb, 8, slevel & 0xff);
                        }
                    } else {
                        /* second escape */
                        put_bits(&s->pb, 1, 1);
                        put_bits(&s->pb, rl->table_vlc[code][1], rl->table_vlc[code][0]);
                        put_bits(&s->pb, 1, sign);
                    }
                } else {
                    /* first escape */
                    put_bits(&s->pb, 1, 1);
                    put_bits(&s->pb, rl->table_vlc[code][1], rl->table_vlc[code][0]);
                    put_bits(&s->pb, 1, sign);
                }
            } else {
                put_bits(&s->pb, 1, sign);
            }
	    last_non_zero = i;
	}
    }
}

/****************************************/
/* decoding stuff */

static VLC mb_non_intra_vlc[4];
static VLC mb_intra_vlc;
static VLC dc_lum_vlc[2];
static VLC dc_chroma_vlc[2];
static VLC v2_dc_lum_vlc;
static VLC v2_dc_chroma_vlc;
static VLC cbpy_vlc;
static VLC v2_intra_cbpc_vlc;
static VLC v2_mb_type_vlc;
static VLC v2_mv_vlc;
static VLC v1_intra_cbpc_vlc;
static VLC v1_inter_cbpc_vlc;
static VLC inter_intra_vlc;

/* this table is practically identical to the one from h263 except that its inverted */
static void init_h263_dc_for_msmpeg4(void)
{
        int level, uni_code, uni_len;

        for(level=-256; level<256; level++){
            int size, v, l;
            /* find number of bits */
            size = 0;
            v = abs(level);
            while (v) {
                v >>= 1;
		    size++;
            }

            if (level < 0)
                l= (-level) ^ ((1 << size) - 1);
            else
                l= level;

            /* luminance h263 */
            uni_code= DCtab_lum[size][0];
            uni_len = DCtab_lum[size][1];
            uni_code ^= (1<<uni_len)-1; //M$ doesnt like compatibility

            if (size > 0) {
                uni_code<<=size; uni_code|=l;
                uni_len+=size;
                if (size > 8){
                    uni_code<<=1; uni_code|=1;
                    uni_len++;
                }
            }
            v2_dc_lum_table[level+256][0]= uni_code;
            v2_dc_lum_table[level+256][1]= uni_len;

            /* chrominance h263 */
            uni_code= DCtab_chrom[size][0];
            uni_len = DCtab_chrom[size][1];
            uni_code ^= (1<<uni_len)-1; //M$ doesnt like compatibility
            
            if (size > 0) {
                uni_code<<=size; uni_code|=l;
                uni_len+=size;
                if (size > 8){
                    uni_code<<=1; uni_code|=1;
                    uni_len++;
                }
            }
            v2_dc_chroma_table[level+256][0]= uni_code;
            v2_dc_chroma_table[level+256][1]= uni_len;

        }
}

/* init all vlc decoding tables */
int ff_msmpeg4_decode_init(MpegEncContext *s)
{
    static int done = 0;
    int i;
    MVTable *mv;

    common_init(s);

    if (!done) {
        done = 1;

        for(i=0;i<NB_RL_TABLES;i++) {
            init_rl(&rl_table[i]);
            init_vlc_rl(&rl_table[i]);
        }
        for(i=0;i<2;i++) {
            mv = &mv_tables[i];
            init_vlc(&mv->vlc, MV_VLC_BITS, mv->n + 1, 
                     mv->table_mv_bits, 1, 1,
                     mv->table_mv_code, 2, 2);
        }

        init_vlc(&dc_lum_vlc[0], DC_VLC_BITS, 120, 
                 &table0_dc_lum[0][1], 8, 4,
                 &table0_dc_lum[0][0], 8, 4);
        init_vlc(&dc_chroma_vlc[0], DC_VLC_BITS, 120, 
                 &table0_dc_chroma[0][1], 8, 4,
                 &table0_dc_chroma[0][0], 8, 4);
        init_vlc(&dc_lum_vlc[1], DC_VLC_BITS, 120, 
                 &table1_dc_lum[0][1], 8, 4,
                 &table1_dc_lum[0][0], 8, 4);
        init_vlc(&dc_chroma_vlc[1], DC_VLC_BITS, 120, 
                 &table1_dc_chroma[0][1], 8, 4,
                 &table1_dc_chroma[0][0], 8, 4);
    
        init_vlc(&v2_dc_lum_vlc, DC_VLC_BITS, 512, 
                 &v2_dc_lum_table[0][1], 8, 4,
                 &v2_dc_lum_table[0][0], 8, 4);
        init_vlc(&v2_dc_chroma_vlc, DC_VLC_BITS, 512, 
                 &v2_dc_chroma_table[0][1], 8, 4,
                 &v2_dc_chroma_table[0][0], 8, 4);
    
        init_vlc(&cbpy_vlc, CBPY_VLC_BITS, 16,
                 &cbpy_tab[0][1], 2, 1,
                 &cbpy_tab[0][0], 2, 1);
        init_vlc(&v2_intra_cbpc_vlc, V2_INTRA_CBPC_VLC_BITS, 4,
                 &v2_intra_cbpc[0][1], 2, 1,
                 &v2_intra_cbpc[0][0], 2, 1);
        init_vlc(&v2_mb_type_vlc, V2_MB_TYPE_VLC_BITS, 8,
                 &v2_mb_type[0][1], 2, 1,
                 &v2_mb_type[0][0], 2, 1);
        init_vlc(&v2_mv_vlc, V2_MV_VLC_BITS, 33,
                 &mvtab[0][1], 2, 1,
                 &mvtab[0][0], 2, 1);

        for(i=0; i<4; i++){
            init_vlc(&mb_non_intra_vlc[i], MB_NON_INTRA_VLC_BITS, 128, 
                     &wmv2_inter_table[i][0][1], 8, 4,
                     &wmv2_inter_table[i][0][0], 8, 4); //FIXME name?
        }
        
        init_vlc(&mb_intra_vlc, MB_INTRA_VLC_BITS, 64, 
                 &table_mb_intra[0][1], 4, 2,
                 &table_mb_intra[0][0], 4, 2);
        
        init_vlc(&v1_intra_cbpc_vlc, V1_INTRA_CBPC_VLC_BITS, 8, 
                 intra_MCBPC_bits, 1, 1,
                 intra_MCBPC_code, 1, 1);
        init_vlc(&v1_inter_cbpc_vlc, V1_INTER_CBPC_VLC_BITS, 25, 
                 inter_MCBPC_bits, 1, 1,
                 inter_MCBPC_code, 1, 1);
        
        init_vlc(&inter_intra_vlc, INTER_INTRA_VLC_BITS, 4, 
                 &table_inter_intra[0][1], 2, 1,
                 &table_inter_intra[0][0], 2, 1);
    }
    
    switch(s->msmpeg4_version){
    case 1:
    case 2:
        s->decode_mb= msmpeg4v12_decode_mb;
        break;
    case 3:
    case 4:
        s->decode_mb= msmpeg4v34_decode_mb;
        break;
    case 5:
        s->decode_mb= wmv2_decode_mb;
        break;
    }
    
    s->slice_height= s->mb_height; //to avoid 1/0 if the first frame isnt a keyframe
    
    return 0;
}

static int decode012(GetBitContext *gb)
{
    int n;
    n = get_bits1(gb);