mpeg12.c

来自「从FFMPEG转换而来的H264解码程序,VC下编译..」· C语言 代码 · 共 1,743 行 · 第 1/5 页

                                s->mv[i][2][0] = ((mx + (mx > 0)) >> 1) + dmx;
                                s->mv[i][2][1] = ((my + (my > 0)) >> 1) + dmy;
                                if(s->picture_structure == PICT_TOP_FIELD)
                                    s->mv[i][2][1]--;
                                else
                                    s->mv[i][2][1]++;
                            }
                        }
                        break;
                    default:
                        av_log(s->avctx, AV_LOG_ERROR, "00 motion_type at %d %d\n", s->mb_x, s->mb_y);
                        return -1;
                    }
                }
            }
        }

        s->mb_intra = 0;
        if (HAS_CBP(mb_type)) {
            s->dsp.clear_blocks(s->block[0]);

            if(!s->chroma_y_shift){
                s->dsp.clear_blocks(s->block[6]);
            }

            cbp = get_vlc2(&s->gb, mb_pat_vlc.table, MB_PAT_VLC_BITS, 1);
            if (cbp < 0 || ((cbp == 0) && (s->chroma_format < 2)) ){
                av_log(s->avctx, AV_LOG_ERROR, "invalid cbp at %d %d\n", s->mb_x, s->mb_y);
                return -1;
            }
            if(mb_block_count > 6){
                 cbp<<= mb_block_count-6;
                 cbp |= get_bits(&s->gb, mb_block_count-6);
            }

#ifdef HAVE_XVMC
            //on 1 we memcpy blocks in xvmcvideo
            if(s->avctx->xvmc_acceleration > 1){
                XVMC_pack_pblocks(s,cbp);
                if(s->swap_uv){
                    exchange_uv(s);
                }
            }
#endif

            if (s->codec_id == CODEC_ID_MPEG2VIDEO) {
                if(s->flags2 & CODEC_FLAG2_FAST){
                    for(i=0;i<6;i++) {
                        if(cbp & 32) {
                            mpeg2_fast_decode_block_non_intra(s, s->pblocks[i], i);
                        } else {
                            s->block_last_index[i] = -1;
                        }
                        cbp+=cbp;
                    }
                }else{
                    cbp<<= 12-mb_block_count;

                    for(i=0;i<mb_block_count;i++) {
                        if ( cbp & (1<<11) ) {
                            if (mpeg2_decode_block_non_intra(s, s->pblocks[i], i) < 0)
                                return -1;
                        } else {
                            s->block_last_index[i] = -1;
                        }
                        cbp+=cbp;
                    }
                }
            } else {
                if(s->flags2 & CODEC_FLAG2_FAST){
                    for(i=0;i<6;i++) {
                        if (cbp & 32) {
                            mpeg1_fast_decode_block_inter(s, s->pblocks[i], i);
                        } else {
                            s->block_last_index[i] = -1;
                        }
                        cbp+=cbp;
                    }
                }else{
                    for(i=0;i<6;i++) {
                        if (cbp & 32) {
                            if (mpeg1_decode_block_inter(s, s->pblocks[i], i) < 0)
                                return -1;
                        } else {
                            s->block_last_index[i] = -1;
                        }
                        cbp+=cbp;
                    }
                }
            }
        }else{
            for(i=0;i<12;i++)
                s->block_last_index[i] = -1;
        }
    }

    s->current_picture.mb_type[ s->mb_x + s->mb_y*s->mb_stride ]= mb_type;

    return 0;
}

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

    code = get_vlc2(&s->gb, mv_vlc.table, MV_VLC_BITS, 2);
    if (code == 0) {
        return pred;
    }
    if (code < 0) {
        return 0xffff;
    }

    sign = get_bits1(&s->gb);
    shift = fcode - 1;
    val = code;
    if (shift) {
        val = (val - 1) << shift;
        val |= get_bits(&s->gb, shift);
        val++;
    }
    if (sign)
        val = -val;
    val += pred;

    /* modulo decoding */
    l= INT_BIT - 5 - shift;
    val = (val<<l)>>l;
    return val;
}

static inline int decode_dc(GetBitContext *gb, int component)
{
    int code, diff;

    if (component == 0) {
        code = get_vlc2(gb, dc_lum_vlc.table, DC_VLC_BITS, 2);
    } else {
        code = get_vlc2(gb, dc_chroma_vlc.table, DC_VLC_BITS, 2);
    }
    if (code < 0){
        av_log(NULL, AV_LOG_ERROR, "invalid dc code at\n");
        return 0xffff;
    }
    if (code == 0) {
        diff = 0;
    } else {
        diff = get_xbits(gb, code);
    }
    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_t * const scantable= s->intra_scantable.permutated;
    const uint16_t *quant_matrix= s->intra_matrix;
    const int qscale= s->qscale;

    /* DC coef */
    component = (n <= 3 ? 0 : n - 4 + 1);
    diff = decode_dc(&s->gb, component);
    if (diff >= 0xffff)
        return -1;
    dc = s->last_dc[component];
    dc += diff;
    s->last_dc[component] = dc;
    block[0] = dc<<3;
    dprintf(s->avctx, "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, 0);

            if(level == 127){
                break;
            } else if(level != 0) {
                i += run;
                j = scantable[i];
                level= (level*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*qscale*quant_matrix[j])>>4;
                    level= (level-1)|1;
                    level= -level;
                }else{
                    level= (level*qscale*quant_matrix[j])>>4;
                    level= (level-1)|1;
                }
            }
            if (i > 63){
                av_log(s->avctx, AV_LOG_ERROR, "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_t * const scantable= s->intra_scantable.permutated;
    const uint16_t *quant_matrix= s->inter_matrix;
    const int qscale= s->qscale;

    {
        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);
        if (((int32_t)GET_CACHE(re, &s->gb)) < 0) {
            level= (3*qscale*quant_matrix[0])>>5;
            level= (level-1)|1;
            if(GET_CACHE(re, &s->gb)&0x40000000)
                level= -level;
            block[0] = level;
            i++;
            SKIP_BITS(re, &s->gb, 2);
            if(((int32_t)GET_CACHE(re, &s->gb)) <= (int32_t)0xBFFFFFFF)
                goto end;
        }

        /* now quantify & encode AC coefs */
        for(;;) {
            GET_RL_VLC(level, run, re, &s->gb, rl->rl_vlc[0], TEX_VLC_BITS, 2, 0);

            if(level != 0) {
                i += run;
                j = scantable[i];
                level= ((level*2+1)*qscale*quant_matrix[j])>>5;
                level= (level-1)|1;
                level = (level ^ SHOW_SBITS(re, &s->gb, 1)) - SHOW_SBITS(re, &s->gb, 1);
                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; SKIP_BITS(re, &s->gb, 8);
                } else if (level == 0) {
                    level = SHOW_UBITS(re, &s->gb, 8)      ; SKIP_BITS(re, &s->gb, 8);
                }
                i += run;
                j = scantable[i];
                if(level<0){
                    level= -level;
                    level= ((level*2+1)*qscale*quant_matrix[j])>>5;
                    level= (level-1)|1;
                    level= -level;
                }else{
                    level= ((level*2+1)*qscale*quant_matrix[j])>>5;
                    level= (level-1)|1;
                }
            }
            if (i > 63){
                av_log(s->avctx, AV_LOG_ERROR, "ac-tex damaged at %d %d\n", s->mb_x, s->mb_y);
                return -1;
            }

            block[j] = level;
            if(((int32_t)GET_CACHE(re, &s->gb)) <= (int32_t)0xBFFFFFFF)
                break;
            UPDATE_CACHE(re, &s->gb);
        }
end:
        LAST_SKIP_BITS(re, &s->gb, 2);
        CLOSE_READER(re, &s->gb);
    }
    s->block_last_index[n] = i;
    return 0;
}

static inline int mpeg1_fast_decode_block_inter(MpegEncContext *s, DCTELEM *block, int n)
{
    int level, i, j, run;
    RLTable *rl = &rl_mpeg1;
    uint8_t * const scantable= s->intra_scantable.permutated;
    const int qscale= s->qscale;

    {
        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);
        if (((int32_t)GET_CACHE(re, &s->gb)) < 0) {
            level= (3*qscale)>>1;
            level= (level-1)|1;
            if(GET_CACHE(re, &s->gb)&0x40000000)
                level= -level;
            block[0] = level;
            i++;
            SKIP_BITS(re, &s->gb, 2);
            if(((int32_t)GET_CACHE(re, &s->gb)) <= (int32_t)0xBFFFFFFF)
                goto end;
        }

        /* now quantify & encode AC coefs */
        for(;;) {
            GET_RL_VLC(level, run, re, &s->gb, rl->rl_vlc[0], TEX_VLC_BITS, 2, 0);

            if(level != 0) {
                i += run;
                j = scantable[i];
                level= ((level*2+1)*qscale)>>1;
                level= (level-1)|1;
                level = (level ^ SHOW_SBITS(re, &s->gb, 1)) - SHOW_SBITS(re, &s->gb, 1);
                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; SKIP_B