mpeg12.c

Trolltech公司发布的图形界面操作系统。可在qt-embedded-2.3.7平台上编译为嵌入式图形界面操作系统。

    if (s->pict_type == P_TYPE && !(mb_type & MB_FOR)) {
        s->mv_dir = MV_DIR_FORWARD;
        s->mv_type = MV_TYPE_16X16;
        s->last_mv[0][0][0] = 0;
        s->last_mv[0][0][1] = 0;
        s->last_mv[0][1][0] = 0;
        s->last_mv[0][1][1] = 0;
        s->mv[0][0][0] = 0;
        s->mv[0][0][1] = 0;
    } else if (mb_type & (MB_FOR | MB_BACK)) {
        /* motion vectors */
        s->mv_dir = 0;
        for(i=0;i<2;i++) {
            if (mb_type & (MB_FOR >> i)) {
                s->mv_dir |= (MV_DIR_FORWARD >> i);
                dprintf("motion_type=%d\n", motion_type);
                switch(motion_type) {
                case MT_FRAME: /* or MT_16X8 */
                    if (s->picture_structure == PICT_FRAME) {
                        /* MT_FRAME */
                        s->mv_type = MV_TYPE_16X16;
                        for(k=0;k<2;k++) {
                            val = mpeg_decode_motion(s, s->mpeg_f_code[i][k], 
                                                     s->last_mv[i][0][k]);
                            s->last_mv[i][0][k] = val;
                            s->last_mv[i][1][k] = val;
                            /* full_pel: only for mpeg1 */
                            if (s->full_pel[i])
                                val = val << 1;
                            s->mv[i][0][k] = val;
                            dprintf("mv%d: %d\n", k, val);
                        }
                    } else {
                        /* MT_16X8 */
                        s->mv_type = MV_TYPE_16X8;
                        for(j=0;j<2;j++) {
                            s->field_select[i][j] = get_bits1(&s->gb);
                            for(k=0;k<2;k++) {
                                val = mpeg_decode_motion(s, s->mpeg_f_code[i][k],
                                                         s->last_mv[i][j][k]);
                                s->last_mv[i][j][k] = val;
                                s->mv[i][j][k] = val;
                            }
                        }
                    }
                    break;
                case MT_FIELD:
                    if (s->picture_structure == PICT_FRAME) {
                        s->mv_type = MV_TYPE_FIELD;
                        for(j=0;j<2;j++) {
                            s->field_select[i][j] = get_bits1(&s->gb);
                            val = mpeg_decode_motion(s, s->mpeg_f_code[i][0],
                                                     s->last_mv[i][j][0]);
                            s->last_mv[i][j][0] = val;
                            s->mv[i][j][0] = val;
                            dprintf("fmx=%d\n", val);
                            val = mpeg_decode_motion(s, s->mpeg_f_code[i][1],
                                                     s->last_mv[i][j][1] >> 1);
                            s->last_mv[i][j][1] = val << 1;
                            s->mv[i][j][1] = val;
                            dprintf("fmy=%d\n", val);
                        }
                    } else {
                        s->mv_type = MV_TYPE_16X16;
                        s->field_select[i][0] = get_bits1(&s->gb);
                        for(k=0;k<2;k++) {
                            val = mpeg_decode_motion(s, s->mpeg_f_code[i][k],
                                                     s->last_mv[i][0][k]);
                            s->last_mv[i][0][k] = val;
                            s->last_mv[i][1][k] = val;
                            s->mv[i][0][k] = val;
                        }
                    }
                    break;
                case MT_DMV:
                    {
                        int dmx, dmy, mx, my, m;

                        mx = mpeg_decode_motion(s, s->mpeg_f_code[i][0], 
                                                s->last_mv[i][0][0]);
                        s->last_mv[i][0][0] = mx;
                        s->last_mv[i][1][0] = mx;
                        dmx = get_dmv(s);
                        my = mpeg_decode_motion(s, s->mpeg_f_code[i][1], 
                                                s->last_mv[i][0][1] >> 1);
                        dmy = get_dmv(s);
                        s->mv_type = MV_TYPE_DMV;
                        /* XXX: totally broken */
                        if (s->picture_structure == PICT_FRAME) {
                            s->last_mv[i][0][1] = my << 1;
                            s->last_mv[i][1][1] = my << 1;

                            m = s->top_field_first ? 1 : 3;
                            /* top -> top pred */
                            s->mv[i][0][0] = mx; 
                            s->mv[i][0][1] = my << 1;
                            s->mv[i][1][0] = ((mx * m + (mx > 0)) >> 1) + dmx;
                            s->mv[i][1][1] = ((my * m + (my > 0)) >> 1) + dmy - 1;
                            m = 4 - m;
                            s->mv[i][2][0] = mx;
                            s->mv[i][2][1] = my << 1;
                            s->mv[i][3][0] = ((mx * m + (mx > 0)) >> 1) + dmx;
                            s->mv[i][3][1] = ((my * m + (my > 0)) >> 1) + dmy + 1;
                        } else {
                            s->last_mv[i][0][1] = my;
                            s->last_mv[i][1][1] = my;
                            s->mv[i][0][0] = mx;
                            s->mv[i][0][1] = my;
                            s->mv[i][1][0] = ((mx + (mx > 0)) >> 1) + dmx;
                            s->mv[i][1][1] = ((my + (my > 0)) >> 1) + dmy - 1 
                                /* + 2 * cur_field */;
                        }
                    }
                    break;
                }
            }
        }
    }

    if ((mb_type & MB_INTRA) && s->concealment_motion_vectors) {
        skip_bits1(&s->gb); /* marker */
    }
    
    if (mb_type & MB_PAT) {
        cbp = get_vlc2(&s->gb, mb_pat_vlc.table, MB_PAT_VLC_BITS, 1);
        if (cbp < 0){
            fprintf(stderr, "invalid cbp at %d %d\n", s->mb_x, s->mb_y);
            return -1;
        }
        cbp++;
    }
    dprintf("cbp=%x\n", cbp);

    if (s->mpeg2) {
        if (s->mb_intra) {
            for(i=0;i<6;i++) {
                if (mpeg2_decode_block_intra(s, block[i], i) < 0)
                    return -1;
            }
        } else {
            for(i=0;i<6;i++) {
                if (cbp & 32) {
                    if (mpeg2_decode_block_non_intra(s, block[i], i) < 0)
                        return -1;
                } else {
                    s->block_last_index[i] = -1;
                }
                cbp+=cbp;
            }
        }
    } else {
        if (s->mb_intra) {
            for(i=0;i<6;i++) {
                if (mpeg1_decode_block_intra(s, block[i], i) < 0)
                    return -1;
            }
        }else{
            for(i=0;i<6;i++) {
                if (cbp & 32) {
                    if (mpeg1_decode_block_inter(s, block[i], i) < 0)
                        return -1;
                } else {
                    s->block_last_index[i] = -1;
                }
                cbp+=cbp;
            }
        }
    }
    return 0;
}

/* as h263, but only 17 codes */
static int mpeg_decode_motion(MpegEncContext *s, int fcode, int pred)
{
    int code, sign, val, m, l, shift;

    code = get_vlc2(&s->gb, mv_vlc.table, MV_VLC_BITS, 2);
    if (code < 0) {
        return 0xffff;
    }
    if (code == 0) {
        return pred;
    }
    sign = get_bits1(&s->gb);
    shift = fcode - 1;
    val = (code - 1) << shift;
    if (shift > 0)
        val |= get_bits(&s->gb, shift);
    val++;
    if (sign)
        val = -val;
    val += pred;
    
    /* modulo decoding */
    l = (1 << shift) * 16;
    m = 2 * l;
    if (val < -l) {
        val += m;
    } else if (val >= l) {
        val -= m;
    }
    return val;
}

static inline int decode_dc(MpegEncContext *s, int component)
{
    int code, diff;

    if (component == 0) {
        code = get_vlc2(&s->gb, dc_lum_vlc.table, DC_VLC_BITS, 2);
    } else {
        code = get_vlc2(&s->gb, dc_chroma_vlc.table, DC_VLC_BITS, 2);
    }
    if (code < 0){
        fprintf(stderr, "invalid dc code at %d %d\n", s->mb_x, s->mb_y);
        return 0xffff;
    }
    if (code == 0) {
        diff = 0;
    } else {
        diff = get_bits(&s->gb, code);
        if ((diff & (1 << (code - 1))) == 0) 
            diff = (-1 << code) | (diff + 1);
    }
    return diff;
}

static inline int mpeg1_decode_block_intra(MpegEncContext *s, 
                               DCTELEM *block, 
                               int n)
{
    int level, dc, diff, i, j, run;
    int component;
    RLTable *rl = &rl_mpeg1;
    UINT8 * const scantable= s->intra_scantable.permutated;
    const UINT16 *quant_matrix= s->intra_matrix;
    const int qscale= s->qscale;

    /* DC coef */
    component = (n <= 3 ? 0 : n - 4 + 1);
    diff = decode_dc(s, component);
    if (diff >= 0xffff)
        return -1;
    dc = s->last_dc[component];
    dc += diff;
    s->last_dc[component] = dc;
    block[0] = dc<<3;
    dprintf("dc=%d diff=%d\n", dc, diff);
    i = 0;
    {
        OPEN_READER(re, &s->gb);    
        /* now quantify & encode AC coefs */
        for(;;) {
            UPDATE_CACHE(re, &s->gb);
            GET_RL_VLC(level, run, re, &s->gb, rl->rl_vlc[0], TEX_VLC_BITS, 2);
            
            if(level == 127){
                break;
            } else if(level != 0) {
                i += run;
                j = scantable[i];
                level= (level*qscale*quant_matrix[j])>>3;
                level= (level-1)|1;
                level = (level ^ SHOW_SBITS(re, &s->gb, 1)) - SHOW_SBITS(re, &s->gb, 1);
                LAST_SKIP_BITS(re, &s->gb, 1);
            } else {
                /* escape */
                run = SHOW_UBITS(re, &s->gb, 6)+1; LAST_SKIP_BITS(re, &s->gb, 6);
                UPDATE_CACHE(re, &s->gb);
                level = SHOW_SBITS(re, &s->gb, 8); SKIP_BITS(re, &s->gb, 8);
                if (level == -128) {
                    level = SHOW_UBITS(re, &s->gb, 8) - 256; LAST_SKIP_BITS(re, &s->gb, 8);
                } else if (level == 0) {
                    level = SHOW_UBITS(re, &s->gb, 8)      ; LAST_SKIP_BITS(re, &s->gb, 8);
                }
                i += run;
                j = scantable[i];
                if(level<0){
                    level= -level;
                    level= (level*qscale*quant_matrix[j])>>3;
                    level= (level-1)|1;
                    level= -level;
                }else{
                    level= (level*qscale*quant_matrix[j])>>3;
                    level= (level-1)|1;
                }
            }
            if (i > 63){
                fprintf(stderr, "ac-tex damaged at %d %d\n", s->mb_x, s->mb_y);
                return -1;
            }

            block[j] = level;
        }
        CLOSE_READER(re, &s->gb);
    }
    s->block_last_index[n] = i;
   return 0;
}

static inline int mpeg1_decode_block_inter(MpegEncContext *s, 
                               DCTELEM *block, 
                               int n)
{
    int level, i, j, run;
    RLTable *rl = &rl_mpeg1;
    UINT8 * const scantable= s->intra_scantable.permutated;
    const UINT16 *quant_matrix= s->inter_matrix;
    const int qscale= s->qscale;

    {
        int v;
        OPEN_READER(re, &s->gb);
        i = -1;
        /* special case for the first coef. no need to add a second vlc table */
        UPDATE_CACHE(re, &s->gb);
        v= SHOW_UBITS(re, &s->gb, 2);
        if (v & 2) {
            LAST_SKIP_BITS(re, &s->gb, 2);
            level= (3*qscale*quant_matrix[0])>>4;
            level= (level-1)|1;
            if(v&1)
                level= -level;
            block[0] = level;
            i++;
        }

        /* now quantify & encode AC coefs */
        for(;;) {
            UPDATE_CACHE(re, &s->gb);
            GET_RL_VLC(level, run, re, &s->gb, rl->rl_vlc[0], TEX_VLC_BITS, 2);
            
            if(level == 127){
                break;
            } else if(level != 0) {
                i += run;
                j = scantable[i];
                level= ((level*2+1)*qscale*quant_matrix[j])>>4;
                level= (level-1)|1;
                level = (level ^ SHOW_SBITS(re, &s->gb, 1)) - SHOW_SBITS(re, &s->gb, 1);
                LAST_SKIP_BITS(re, &s->gb, 1);
            } else {
                /* escape */
                run = SHOW_UBITS(re, &s->gb, 6)+1; LAST_SKIP_BITS(re, &s->gb, 6);
                UPDATE_CACHE(re, &s->gb);
                level = SHOW_SBITS(re, &s->gb, 8); SKIP_BITS(re, &s->gb, 8);
                if (level == -128) {
                    level = SHOW_UBITS(re, &s->gb, 8) - 256; LAST_SKIP_BITS(re, &s->gb, 8);
                } else if (level == 0) {
                    level = SHOW_UBITS(re, &s->gb, 8)      ; LAST_SKIP_BITS(re, &s->gb, 8);
                }
                i += run;
                j = scantable[i];
                if(level<0){
                    level= -level;
                    level= ((level*2+1)*qscale*quant_matrix[j])>>4;
                    level= (level-1)|1;
                    level= -level;
                }else{
                    level= ((level*2+1)*qscale*quant_matrix[j])>>4;
                    level= (level-1)|1;
                }
            }
            if (i > 63){
                fprintf(stderr, "ac-tex damaged at %d %d\n", s->mb_x, s->mb_y);
                return -1;
            }

            block[j] = level;
        }
        CLOSE_READER(re, &s->gb);
    }
    s->block_last_index[n] = i;
    return 0;
}

/* Also does unquantization here, since I will never support mpeg2
   encoding */
static inline int mpeg2_decode_block_non_intra(MpegEncContext *s, 
                               DCTELEM *block, 
                               int n)
{
    int level, i, j, run;
    RLTable *rl = &rl_mpeg1;
    UINT8 * const scantable= s->intra_scantable.permutated;
    const UINT16 *quant_matrix;
    const int qscale= s->qscale;
    int mismatch;

    mismatch = 1;

    {
        int v;
        OPEN_READER(re, &s->gb);
        i = -1;
        if (n < 4)
            quant_matrix = s->inter_matrix;