msmpeg4.c

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            int val = ((code >> (5 - i)) & 1);
            if (i < 4) {
                int pred = coded_block_pred(s, i, &coded_val);
                val = val ^ pred;
                *coded_val = val;
            }
            cbp |= val << (5 - i);
        }
    }

    if (!s->mb_intra) {
        int mx, my;
//printf("P at %d %d\n", s->mb_x, s->mb_y);
        if(s->per_mb_rl_table && cbp){
            s->rl_table_index = decode012(&s->gb);
            s->rl_chroma_table_index = s->rl_table_index;
        }
        set_stat(ST_MV);
        h263_pred_motion(s, 0, &mx, &my);
        if (msmpeg4_decode_motion(s, &mx, &my) < 0)
            return -1;
        s->mv_dir = MV_DIR_FORWARD;
        s->mv_type = MV_TYPE_16X16;
        s->mv[0][0][0] = mx;
        s->mv[0][0][1] = my;
        *mb_type_ptr = MB_TYPE_L0 | MB_TYPE_16x16;
    } else {
//printf("I at %d %d %d %06X\n", s->mb_x, s->mb_y, ((cbp&3)? 1 : 0) +((cbp&0x3C)? 2 : 0), show_bits(&s->gb, 24));
        set_stat(ST_INTRA_MB);
        s->ac_pred = get_bits1(&s->gb);
        *mb_type_ptr = MB_TYPE_INTRA;
        if(s->inter_intra_pred){
            s->h263_aic_dir= get_vlc2(&s->gb, inter_intra_vlc.table, INTER_INTRA_VLC_BITS, 1);
//            printf("%d%d %d %d/", s->ac_pred, s->h263_aic_dir, s->mb_x, s->mb_y);
        }
        if(s->per_mb_rl_table && cbp){
            s->rl_table_index = decode012(&s->gb);
            s->rl_chroma_table_index = s->rl_table_index;
        }
    }

    for (i = 0; i < 6; i++) {
        if (msmpeg4_decode_block(s, block[i], i, (cbp >> (5 - i)) & 1, NULL) < 0)
	{
	    av_log(s->avctx, AV_LOG_ERROR, "\nerror while decoding block: %d x %d (%d)\n", s->mb_x, s->mb_y, i);
	    return -1;
	}
    }
    
    return 0;
}
//#define ERROR_DETAILS
static inline int msmpeg4_decode_block(MpegEncContext * s, DCTELEM * block,
                              int n, int coded, const uint8_t *scan_table)
{
    int level, i, last, run, run_diff;
    int dc_pred_dir;
    RLTable *rl;
    RL_VLC_ELEM *rl_vlc;
    int qmul, qadd;

    if (s->mb_intra) {
        qmul=1;
        qadd=0;

	/* DC coef */
        set_stat(ST_DC);
        level = msmpeg4_decode_dc(s, n, &dc_pred_dir);
        
        if (level < 0){
            av_log(s->avctx, AV_LOG_ERROR, "dc overflow- block: %d qscale: %d//\n", n, s->qscale);
            if(s->inter_intra_pred) level=0;
            else                    return -1;
        }
        if (n < 4) {
            rl = &rl_table[s->rl_table_index];
            if(level > 256*s->y_dc_scale){
                av_log(s->avctx, AV_LOG_ERROR, "dc overflow+ L qscale: %d//\n", s->qscale);
                if(!s->inter_intra_pred) return -1;
            }
        } else {
            rl = &rl_table[3 + s->rl_chroma_table_index];
            if(level > 256*s->c_dc_scale){
                av_log(s->avctx, AV_LOG_ERROR, "dc overflow+ C qscale: %d//\n", s->qscale);
                if(!s->inter_intra_pred) return -1;
            }
        }
        block[0] = level;

        run_diff = 0;
        i = 0;
        if (!coded) {
            goto not_coded;
        }
        if (s->ac_pred) {
            if (dc_pred_dir == 0) 
                scan_table = s->intra_v_scantable.permutated; /* left */
            else
                scan_table = s->intra_h_scantable.permutated; /* top */
        } else {
            scan_table = s->intra_scantable.permutated;
        }
        set_stat(ST_INTRA_AC);
        rl_vlc= rl->rl_vlc[0];
    } else {
        qmul = s->qscale << 1;
        qadd = (s->qscale - 1) | 1;
        i = -1;
        rl = &rl_table[3 + s->rl_table_index];

        if(s->msmpeg4_version==2)
            run_diff = 0;
        else
            run_diff = 1;

        if (!coded) {
            s->block_last_index[n] = i;
            return 0;
        }
        if(!scan_table)
            scan_table = s->inter_scantable.permutated;
        set_stat(ST_INTER_AC);
        rl_vlc= rl->rl_vlc[s->qscale];
    }
  {
    OPEN_READER(re, &s->gb);
    for(;;) {
        UPDATE_CACHE(re, &s->gb);
        GET_RL_VLC(level, run, re, &s->gb, rl_vlc, TEX_VLC_BITS, 2);
        if (level==0) {
            int cache;
            cache= GET_CACHE(re, &s->gb);
            /* escape */
            if (s->msmpeg4_version==1 || (cache&0x80000000)==0) {
                if (s->msmpeg4_version==1 || (cache&0x40000000)==0) {
                    /* third escape */
                    if(s->msmpeg4_version!=1) LAST_SKIP_BITS(re, &s->gb, 2);
                    UPDATE_CACHE(re, &s->gb);
                    if(s->msmpeg4_version<=3){
                        last=  SHOW_UBITS(re, &s->gb, 1); SKIP_CACHE(re, &s->gb, 1);
                        run=   SHOW_UBITS(re, &s->gb, 6); SKIP_CACHE(re, &s->gb, 6);
                        level= SHOW_SBITS(re, &s->gb, 8); LAST_SKIP_CACHE(re, &s->gb, 8);
                        SKIP_COUNTER(re, &s->gb, 1+6+8);
                    }else{                        
                        int sign;
                        last=  SHOW_UBITS(re, &s->gb, 1); SKIP_BITS(re, &s->gb, 1);
                        if(!s->esc3_level_length){
                            int ll;
                            //printf("ESC-3 %X at %d %d\n", show_bits(&s->gb, 24), s->mb_x, s->mb_y);
                            if(s->qscale<8){
                                ll= SHOW_UBITS(re, &s->gb, 3); SKIP_BITS(re, &s->gb, 3);
                                if(ll==0){
                                    if(SHOW_UBITS(re, &s->gb, 1)) av_log(s->avctx, AV_LOG_ERROR, "cool a new vlc code ,contact the ffmpeg developers and upload the file\n");
                                    SKIP_BITS(re, &s->gb, 1);
                                    ll=8;
                                }
                            }else{
                                ll=2;
                                while(ll<8 && SHOW_UBITS(re, &s->gb, 1)==0){
                                    ll++;
                                    SKIP_BITS(re, &s->gb, 1);
                                }
                                if(ll<8) SKIP_BITS(re, &s->gb, 1);
                            }

                            s->esc3_level_length= ll;
                            s->esc3_run_length= SHOW_UBITS(re, &s->gb, 2) + 3; SKIP_BITS(re, &s->gb, 2);
//printf("level length:%d, run length: %d\n", ll, s->esc3_run_length);
                            UPDATE_CACHE(re, &s->gb);
                        }
                        run=   SHOW_UBITS(re, &s->gb, s->esc3_run_length); 
                        SKIP_BITS(re, &s->gb, s->esc3_run_length);
                        
                        sign=  SHOW_UBITS(re, &s->gb, 1); 
                        SKIP_BITS(re, &s->gb, 1);
                        
                        level= SHOW_UBITS(re, &s->gb, s->esc3_level_length); 
                        SKIP_BITS(re, &s->gb, s->esc3_level_length);
                        if(sign) level= -level;
                    }
//printf("level: %d, run: %d at %d %d\n", level, run, s->mb_x, s->mb_y);
#if 0 // waste of time / this will detect very few errors
                    {
                        const int abs_level= ABS(level);
                        const int run1= run - rl->max_run[last][abs_level] - run_diff;
                        if(abs_level<=MAX_LEVEL && run<=MAX_RUN){
                            if(abs_level <= rl->max_level[last][run]){
                                fprintf(stderr, "illegal 3. esc, vlc encoding possible\n");
                                return DECODING_AC_LOST;
                            }
                            if(abs_level <= rl->max_level[last][run]*2){
                                fprintf(stderr, "illegal 3. esc, esc 1 encoding possible\n");
                                return DECODING_AC_LOST;
                            }
                            if(run1>=0 && abs_level <= rl->max_level[last][run1]){
                                fprintf(stderr, "illegal 3. esc, esc 2 encoding possible\n");
                                return DECODING_AC_LOST;
                            }
                        }
                    }
#endif
		    //level = level * qmul + (level>0) * qadd - (level<=0) * qadd ;
		    if (level>0) level= level * qmul + qadd;
                    else         level= level * qmul - qadd;
#if 0 // waste of time too :(
                    if(level>2048 || level<-2048){
                        fprintf(stderr, "|level| overflow in 3. esc\n");
                        return DECODING_AC_LOST;
                    }
#endif
                    i+= run + 1;
                    if(last) i+=192;
#ifdef ERROR_DETAILS
                if(run==66)
                    fprintf(stderr, "illegal vlc code in ESC3 level=%d\n", level);
                else if((i>62 && i<192) || i>192+63)
                    fprintf(stderr, "run overflow in ESC3 i=%d run=%d level=%d\n", i, run, level);
#endif
                } else {
                    /* second escape */
#if MIN_CACHE_BITS < 23
                    LAST_SKIP_BITS(re, &s->gb, 2);
                    UPDATE_CACHE(re, &s->gb);
#else
                    SKIP_BITS(re, &s->gb, 2);
#endif
                    GET_RL_VLC(level, run, re, &s->gb, rl_vlc, TEX_VLC_BITS, 2);
                    i+= run + rl->max_run[run>>7][level/qmul] + run_diff; //FIXME opt indexing
                    level = (level ^ SHOW_SBITS(re, &s->gb, 1)) - SHOW_SBITS(re, &s->gb, 1);
                    LAST_SKIP_BITS(re, &s->gb, 1);
#ifdef ERROR_DETAILS
                if(run==66)
                    fprintf(stderr, "illegal vlc code in ESC2 level=%d\n", level);
                else if((i>62 && i<192) || i>192+63)
                    fprintf(stderr, "run overflow in ESC2 i=%d run=%d level=%d\n", i, run, level);
#endif
                }
            } else {
                /* first escape */
#if MIN_CACHE_BITS < 22
                LAST_SKIP_BITS(re, &s->gb, 1);
                UPDATE_CACHE(re, &s->gb);
#else
                SKIP_BITS(re, &s->gb, 1);
#endif
                GET_RL_VLC(level, run, re, &s->gb, rl_vlc, TEX_VLC_BITS, 2);
                i+= run;
                level = level + rl->max_level[run>>7][(run-1)&63] * qmul;//FIXME opt indexing
                level = (level ^ SHOW_SBITS(re, &s->gb, 1)) - SHOW_SBITS(re, &s->gb, 1);
                LAST_SKIP_BITS(re, &s->gb, 1);
#ifdef ERROR_DETAILS
                if(run==66)
                    fprintf(stderr, "illegal vlc code in ESC1 level=%d\n", level);
                else if((i>62 && i<192) || i>192+63)
                    fprintf(stderr, "run overflow in ESC1 i=%d run=%d level=%d\n", i, run, level);
#endif
            }
        } else {
            i+= run;
            level = (level ^ SHOW_SBITS(re, &s->gb, 1)) - SHOW_SBITS(re, &s->gb, 1);
            LAST_SKIP_BITS(re, &s->gb, 1);
#ifdef ERROR_DETAILS
                if(run==66)
                    fprintf(stderr, "illegal vlc code level=%d\n", level);
                else if((i>62 && i<192) || i>192+63)
                    fprintf(stderr, "run overflow i=%d run=%d level=%d\n", i, run, level);
#endif
        }
        if (i > 62){
            i-= 192;
            if(i&(~63)){
                const int left= s->gb.size_in_bits - get_bits_count(&s->gb);
                if(((i+192 == 64 && level/qmul==-1) || s->error_resilience<=1) && left>=0){
                    av_log(s->avctx, AV_LOG_ERROR, "ignoring overflow at %d %d\n", s->mb_x, s->mb_y);
                    break;
                }else{
                    av_log(s->avctx, AV_LOG_ERROR, "ac-tex damaged at %d %d\n", s->mb_x, s->mb_y);
                    return -1;
                }
            }

            block[scan_table[i]] = level;
            break;
        }

        block[scan_table[i]] = level;
    }
    CLOSE_READER(re, &s->gb);
  }
 not_coded:
    if (s->mb_intra) {
        mpeg4_pred_ac(s, block, n, dc_pred_dir);
        if (s->ac_pred) {
            i = 63; /* XXX: not optimal */
        }
    }
    if(s->msmpeg4_version>=4 && i>0) i=63; //FIXME/XXX optimize
    s->block_last_index[n] = i;
    
    return 0;
}

static int msmpeg4_decode_dc(MpegEncContext * s, int n, int *dir_ptr)
{
    int level, pred;

    if(s->msmpeg4_version<=2){
        if (n < 4) {
            level = get_vlc2(&s->gb, v2_dc_lum_vlc.table, DC_VLC_BITS, 3);
        } else {
            level = get_vlc2(&s->gb, v2_dc_chroma_vlc.table, DC_VLC_BITS, 3);
        }
        if (level < 0) 
            return -1;
        level-=256;
    }else{  //FIXME optimize use unified tables & index
        if (n < 4) {
            level = get_vlc2(&s->gb, dc_lum_vlc[s->dc_table_index].table, DC_VLC_BITS, 3);
        } else {
            level = get_vlc2(&s->gb, dc_chroma_vlc[s->dc_table_index].table, DC_VLC_BITS, 3);
        }
        if (level < 0){
            av_log(s->avctx, AV_LOG_ERROR, "illegal dc vlc\n");
            return -1;
        }

        if (level == DC_MAX) {
            level = get_bits(&s->gb, 8);
            if (get_bits1(&s->gb))
                level = -level;
        } else if (level != 0) {
            if (get_bits1(&s->gb))
                level = -level;
        }
    }

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

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

    return level;
}

static int msmpeg4_decode_motion(MpegEncContext * s, 
                                 int *mx_ptr, int *my_ptr)
{
    MVTable *mv;
    int code, mx, my;

    mv = &mv_tables[s->mv_table_index];

    code = get_vlc2(&s->gb, mv->vlc.table, MV_VLC_BITS, 2);
    if (code < 0){
        av_log(s->avctx, AV_LOG_ERROR, "illegal MV code at %d %d\n", s->mb_x, s->mb_y);
        return -1;
    }
    if (code == mv->n) {
//printf("MV ESC %X at %d %d\n", show_bits(&s->gb, 24), s->mb_x, s->mb_y);
        mx = get_bits(&s->gb, 6);
        my = get_bits(&s->gb, 6);
    } else {
        mx = mv->table_mvx[code];
        my = mv->table_mvy[code];
    }

    mx += *mx_ptr - 32;
    my += *my_ptr - 32;
    /* WARNING : they do not do exactly modulo encoding */
    if (mx <= -64)
        mx += 64;
    else if (mx >= 64)
        mx -= 64;

    if (my <= -64)
        my += 64;
    else if (my >= 64)
        my -= 64;
    *mx_ptr = mx;
    *my_ptr = my;
    return 0;
}

/* cleanest way to support it
 * there is too much shared between versions so that we cant have 1 file per version & 1 common
 * as allmost everything would be in the common file 
 */
#include "wmv2.c"