mpeg12.c

arm平台下的H264编码和解码源代码

            /* just parse them */
            if (s->picture_structure != PICT_FRAME) 
                skip_bits1(&s->gb); /* field select */
            
            s->mv[0][0][0]= s->last_mv[0][0][0]= s->last_mv[0][1][0] = 
                mpeg_decode_motion(s, s->mpeg_f_code[0][0], s->last_mv[0][0][0]);
            s->mv[0][0][1]= s->last_mv[0][0][1]= s->last_mv[0][1][1] = 
                mpeg_decode_motion(s, s->mpeg_f_code[0][1], s->last_mv[0][0][1]);

            skip_bits1(&s->gb); /* marker */
        }else
            memset(s->last_mv, 0, sizeof(s->last_mv)); /* reset mv prediction */
        s->mb_intra = 1;
#ifdef HAVE_XVMC
        //one 1 we memcpy blocks in xvmcvideo
        if(s->avctx->xvmc_acceleration > 1){
            XVMC_pack_pblocks(s,-1);//inter are always full blocks
            if(s->swap_uv){
                exchange_uv(s);
            }
        }
#endif

        if (s->codec_id == CODEC_ID_MPEG2VIDEO) {
            for(i=0;i<4+(1<<s->chroma_format);i++) {
                if (mpeg2_decode_block_intra(s, s->pblocks[i], i) < 0)
                    return -1;
            }
        } else {
            for(i=0;i<6;i++) {
                if (mpeg1_decode_block_intra(s, s->pblocks[i], i) < 0)
                    return -1;
            }
        }
    } else {
        if (mb_type & MB_TYPE_ZERO_MV){
#ifndef WINCE //assert
            assert(mb_type & MB_TYPE_CBP);
#endif
            /* compute dct type */
            if (s->picture_structure == PICT_FRAME && //FIXME add a interlaced_dct coded var?
                !s->frame_pred_frame_dct) {
                s->interlaced_dct = get_bits1(&s->gb);
            }

            if (IS_QUANT(mb_type))
                s->qscale = get_qscale(s);

            s->mv_dir = MV_DIR_FORWARD;
            if(s->picture_structure == PICT_FRAME)
                s->mv_type = MV_TYPE_16X16;
            else{
                s->mv_type = MV_TYPE_FIELD;
                mb_type |= MB_TYPE_INTERLACED;
                s->field_select[0][0]= s->picture_structure - 1;
            }
            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{
#ifndef WINCE //assert
            assert(mb_type & MB_TYPE_L0L1);
#endif
//FIXME decide if MBs in field pictures are MB_TYPE_INTERLACED
            /* get additionnal motion vector type */
            if (s->frame_pred_frame_dct) 
                motion_type = MT_FRAME;
            else{
                motion_type = get_bits(&s->gb, 2);
            }

            /* compute dct type */
            if (s->picture_structure == PICT_FRAME && //FIXME add a interlaced_dct coded var?
                !s->frame_pred_frame_dct && HAS_CBP(mb_type)) {
                s->interlaced_dct = get_bits1(&s->gb);
            }

            if (IS_QUANT(mb_type))
                s->qscale = get_qscale(s);

            /* motion vectors */
            s->mv_dir = 0;
            for(i=0;i<2;i++) {
                if (USES_LIST(mb_type, 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 */
                            mb_type |= MB_TYPE_16x16; 
                            s->mv_type = MV_TYPE_16X16;
                            s->mv[i][0][0]= s->last_mv[i][0][0]= s->last_mv[i][1][0] = 
                                mpeg_decode_motion(s, s->mpeg_f_code[i][0], s->last_mv[i][0][0]);
                            s->mv[i][0][1]= s->last_mv[i][0][1]= s->last_mv[i][1][1] = 
                                mpeg_decode_motion(s, s->mpeg_f_code[i][1], s->last_mv[i][0][1]);
                            /* full_pel: only for mpeg1 */
                            if (s->full_pel[i]){
                                s->mv[i][0][0] <<= 1;
                                s->mv[i][0][1] <<= 1;
                            }
                        } else {
                            /* MT_16X8 */
                            mb_type |= MB_TYPE_16x8 | MB_TYPE_INTERLACED; 
                            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:
                        s->mv_type = MV_TYPE_FIELD;
                        if (s->picture_structure == PICT_FRAME) {
                            mb_type |= MB_TYPE_16x8 | MB_TYPE_INTERLACED; 
                            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 {
                            mb_type |= MB_TYPE_16x16 | MB_TYPE_INTERLACED; 
                            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;


                            s->last_mv[i][0][1] = my<<1;
                            s->last_mv[i][1][1] = my<<1;

                            s->mv[i][0][0] = mx;
                            s->mv[i][0][1] = my;
                            s->mv[i][1][0] = mx;//not used
                            s->mv[i][1][1] = my;//not used

                            if (s->picture_structure == PICT_FRAME) {
                                mb_type |= MB_TYPE_16x16 | MB_TYPE_INTERLACED; 

                                //m = 1 + 2 * s->top_field_first;
                                m = s->top_field_first ? 1 : 3;

                                /* top -> top pred */
                                s->mv[i][2][0] = ((mx * m + (mx > 0)) >> 1) + dmx;
                                s->mv[i][2][1] = ((my * m + (my > 0)) >> 1) + dmy - 1;
                                m = 4 - m;
                                s->mv[i][3][0] = ((mx * m + (mx > 0)) >> 1) + dmx;
                                s->mv[i][3][1] = ((my * m + (my > 0)) >> 1) + dmy + 1;
                            } else {
                                mb_type |= MB_TYPE_16x16;

                                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)) {
            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(s->chroma_format == 2){//CHROMA422
                 cbp|= ( get_bits(&s->gb,2) ) << 6;
            }else
            if(s->chroma_format >  2){//CHROMA444
                 cbp|= ( get_bits(&s->gb,6) ) << 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) {
                for(i=0;i<6;i++) {
                    if (cbp & (1<<(5-i)) ) {
                        if (mpeg2_decode_block_non_intra(s, s->pblocks[i], i) < 0)
                            return -1;
                    } else {
                        s->block_last_index[i] = -1;
                    }
                }
                if (s->chroma_format >= 2) {
                    if (s->chroma_format == 2) {//CHROMA_422)
                        for(i=6;i<8;i++) {
                            if (cbp & (1<<(6+7-i)) ) {
                                if (mpeg2_decode_block_non_intra(s, s->pblocks[i], i) < 0)
                                    return -1;
                            } else {
                                s->block_last_index[i] = -1;
                            }
                        }
                    }else{ /*CHROMA_444*/
                        for(i=6;i<12;i++) {
                            if (cbp & (1<<(6+11-i)) ) {
                                if (mpeg2_decode_block_non_intra(s, s->pblocks[i], i) < 0)
                                    return -1;
                            } else {
                                s->block_last_index[i] = -1;
                            }
                        }
                    }
                }
            } 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<6;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 = 1 << (shift+4);
    val = ((val + l)&(l*2-1)) - 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("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])>>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 */