mpegvideo_common.h

ffmpeg的完整源代码和作者自己写的文档。不但有在Linux的工程哦

        my = motion_y / 4;
        uvdxy = 0;
        uvsrc_x = s->mb_x*8 + mx;
        uvsrc_y = s->mb_y*8 + my;
    } else {
        if(s->chroma_y_shift){
            mx = motion_x / 2;
            my = motion_y / 2;
            uvdxy = ((my & 1) << 1) | (mx & 1);
            uvsrc_x = s->mb_x* 8               + (mx >> 1);
            uvsrc_y = (s->mb_y<<(3-field_based)) + (my >> 1);
        } else {
            if(s->chroma_x_shift){
            //Chroma422
                mx = motion_x / 2;
                uvdxy = ((motion_y & 1) << 1) | (mx & 1);
                uvsrc_x = s->mb_x* 8           + (mx >> 1);
                uvsrc_y = src_y;
            } else {
            //Chroma444
                uvdxy = dxy;
                uvsrc_x = src_x;
                uvsrc_y = src_y;
            }
        }
    }

    ptr_y  = ref_picture[0] + src_y * linesize + src_x;
    ptr_cb = ref_picture[1] + uvsrc_y * uvlinesize + uvsrc_x;
    ptr_cr = ref_picture[2] + uvsrc_y * uvlinesize + uvsrc_x;

    if(   (unsigned)src_x > s->h_edge_pos - (motion_x&1) - 16
       || (unsigned)src_y >    v_edge_pos - (motion_y&1) - h){
            if(s->codec_id == CODEC_ID_MPEG2VIDEO ||
               s->codec_id == CODEC_ID_MPEG1VIDEO){
                av_log(s->avctx,AV_LOG_DEBUG,"MPEG motion vector out of boundary\n");
                return ;
            }
            ff_emulated_edge_mc(s->edge_emu_buffer, ptr_y, s->linesize, 17, 17+field_based,
                             src_x, src_y<<field_based, s->h_edge_pos, s->v_edge_pos);
            ptr_y = s->edge_emu_buffer;
            if(!ENABLE_GRAY || !(s->flags&CODEC_FLAG_GRAY)){
                uint8_t *uvbuf= s->edge_emu_buffer+18*s->linesize;
                ff_emulated_edge_mc(uvbuf  , ptr_cb, s->uvlinesize, 9, 9+field_based,
                                 uvsrc_x, uvsrc_y<<field_based, s->h_edge_pos>>1, s->v_edge_pos>>1);
                ff_emulated_edge_mc(uvbuf+16, ptr_cr, s->uvlinesize, 9, 9+field_based,
                                 uvsrc_x, uvsrc_y<<field_based, s->h_edge_pos>>1, s->v_edge_pos>>1);
                ptr_cb= uvbuf;
                ptr_cr= uvbuf+16;
            }
    }

    if(bottom_field){ //FIXME use this for field pix too instead of the obnoxious hack which changes picture.data
        dest_y += s->linesize;
        dest_cb+= s->uvlinesize;
        dest_cr+= s->uvlinesize;
    }

    if(field_select){
        ptr_y += s->linesize;
        ptr_cb+= s->uvlinesize;
        ptr_cr+= s->uvlinesize;
    }

    pix_op[0][dxy](dest_y, ptr_y, linesize, h);

    if(!ENABLE_GRAY || !(s->flags&CODEC_FLAG_GRAY)){
        pix_op[s->chroma_x_shift][uvdxy](dest_cb, ptr_cb, uvlinesize, h >> s->chroma_y_shift);
        pix_op[s->chroma_x_shift][uvdxy](dest_cr, ptr_cr, uvlinesize, h >> s->chroma_y_shift);
    }
    if((ENABLE_H261_ENCODER || ENABLE_H261_DECODER) && s->out_format == FMT_H261){
        ff_h261_loop_filter(s);
    }
}

//FIXME move to dsputil, avg variant, 16x16 version
static inline void put_obmc(uint8_t *dst, uint8_t *src[5], int stride){
    int x;
    uint8_t * const top   = src[1];
    uint8_t * const left  = src[2];
    uint8_t * const mid   = src[0];
    uint8_t * const right = src[3];
    uint8_t * const bottom= src[4];
#define OBMC_FILTER(x, t, l, m, r, b)\
    dst[x]= (t*top[x] + l*left[x] + m*mid[x] + r*right[x] + b*bottom[x] + 4)>>3
#define OBMC_FILTER4(x, t, l, m, r, b)\
    OBMC_FILTER(x         , t, l, m, r, b);\
    OBMC_FILTER(x+1       , t, l, m, r, b);\
    OBMC_FILTER(x  +stride, t, l, m, r, b);\
    OBMC_FILTER(x+1+stride, t, l, m, r, b);

    x=0;
    OBMC_FILTER (x  , 2, 2, 4, 0, 0);
    OBMC_FILTER (x+1, 2, 1, 5, 0, 0);
    OBMC_FILTER4(x+2, 2, 1, 5, 0, 0);
    OBMC_FILTER4(x+4, 2, 0, 5, 1, 0);
    OBMC_FILTER (x+6, 2, 0, 5, 1, 0);
    OBMC_FILTER (x+7, 2, 0, 4, 2, 0);
    x+= stride;
    OBMC_FILTER (x  , 1, 2, 5, 0, 0);
    OBMC_FILTER (x+1, 1, 2, 5, 0, 0);
    OBMC_FILTER (x+6, 1, 0, 5, 2, 0);
    OBMC_FILTER (x+7, 1, 0, 5, 2, 0);
    x+= stride;
    OBMC_FILTER4(x  , 1, 2, 5, 0, 0);
    OBMC_FILTER4(x+2, 1, 1, 6, 0, 0);
    OBMC_FILTER4(x+4, 1, 0, 6, 1, 0);
    OBMC_FILTER4(x+6, 1, 0, 5, 2, 0);
    x+= 2*stride;
    OBMC_FILTER4(x  , 0, 2, 5, 0, 1);
    OBMC_FILTER4(x+2, 0, 1, 6, 0, 1);
    OBMC_FILTER4(x+4, 0, 0, 6, 1, 1);
    OBMC_FILTER4(x+6, 0, 0, 5, 2, 1);
    x+= 2*stride;
    OBMC_FILTER (x  , 0, 2, 5, 0, 1);
    OBMC_FILTER (x+1, 0, 2, 5, 0, 1);
    OBMC_FILTER4(x+2, 0, 1, 5, 0, 2);
    OBMC_FILTER4(x+4, 0, 0, 5, 1, 2);
    OBMC_FILTER (x+6, 0, 0, 5, 2, 1);
    OBMC_FILTER (x+7, 0, 0, 5, 2, 1);
    x+= stride;
    OBMC_FILTER (x  , 0, 2, 4, 0, 2);
    OBMC_FILTER (x+1, 0, 1, 5, 0, 2);
    OBMC_FILTER (x+6, 0, 0, 5, 1, 2);
    OBMC_FILTER (x+7, 0, 0, 4, 2, 2);
}

/* obmc for 1 8x8 luma block */
static inline void obmc_motion(MpegEncContext *s,
                               uint8_t *dest, uint8_t *src,
                               int src_x, int src_y,
                               op_pixels_func *pix_op,
                               int16_t mv[5][2]/* mid top left right bottom*/)
#define MID    0
{
    int i;
    uint8_t *ptr[5];

    assert(s->quarter_sample==0);

    for(i=0; i<5; i++){
        if(i && mv[i][0]==mv[MID][0] && mv[i][1]==mv[MID][1]){
            ptr[i]= ptr[MID];
        }else{
            ptr[i]= s->obmc_scratchpad + 8*(i&1) + s->linesize*8*(i>>1);
            hpel_motion(s, ptr[i], src, 0, 0,
                        src_x, src_y,
                        s->width, s->height, s->linesize,
                        s->h_edge_pos, s->v_edge_pos,
                        8, 8, pix_op,
                        mv[i][0], mv[i][1]);
        }
    }

    put_obmc(dest, ptr, s->linesize);
}

static inline void qpel_motion(MpegEncContext *s,
                               uint8_t *dest_y, uint8_t *dest_cb, uint8_t *dest_cr,
                               int field_based, int bottom_field, int field_select,
                               uint8_t **ref_picture, op_pixels_func (*pix_op)[4],
                               qpel_mc_func (*qpix_op)[16],
                               int motion_x, int motion_y, int h)
{
    uint8_t *ptr_y, *ptr_cb, *ptr_cr;
    int dxy, uvdxy, mx, my, src_x, src_y, uvsrc_x, uvsrc_y, v_edge_pos, linesize, uvlinesize;

    dxy = ((motion_y & 3) << 2) | (motion_x & 3);
    src_x = s->mb_x *  16                 + (motion_x >> 2);
    src_y = s->mb_y * (16 >> field_based) + (motion_y >> 2);

    v_edge_pos = s->v_edge_pos >> field_based;
    linesize = s->linesize << field_based;
    uvlinesize = s->uvlinesize << field_based;

    if(field_based){
        mx= motion_x/2;
        my= motion_y>>1;
    }else if(s->workaround_bugs&FF_BUG_QPEL_CHROMA2){
        static const int rtab[8]= {0,0,1,1,0,0,0,1};
        mx= (motion_x>>1) + rtab[motion_x&7];
        my= (motion_y>>1) + rtab[motion_y&7];
    }else if(s->workaround_bugs&FF_BUG_QPEL_CHROMA){
        mx= (motion_x>>1)|(motion_x&1);
        my= (motion_y>>1)|(motion_y&1);
    }else{
        mx= motion_x/2;
        my= motion_y/2;
    }
    mx= (mx>>1)|(mx&1);
    my= (my>>1)|(my&1);

    uvdxy= (mx&1) | ((my&1)<<1);
    mx>>=1;
    my>>=1;

    uvsrc_x = s->mb_x *  8                 + mx;
    uvsrc_y = s->mb_y * (8 >> field_based) + my;

    ptr_y  = ref_picture[0] +   src_y *   linesize +   src_x;
    ptr_cb = ref_picture[1] + uvsrc_y * uvlinesize + uvsrc_x;
    ptr_cr = ref_picture[2] + uvsrc_y * uvlinesize + uvsrc_x;

    if(   (unsigned)src_x > s->h_edge_pos - (motion_x&3) - 16
       || (unsigned)src_y >    v_edge_pos - (motion_y&3) - h  ){
        ff_emulated_edge_mc(s->edge_emu_buffer, ptr_y, s->linesize, 17, 17+field_based,
                         src_x, src_y<<field_based, s->h_edge_pos, s->v_edge_pos);
        ptr_y= s->edge_emu_buffer;
        if(!ENABLE_GRAY || !(s->flags&CODEC_FLAG_GRAY)){
            uint8_t *uvbuf= s->edge_emu_buffer + 18*s->linesize;
            ff_emulated_edge_mc(uvbuf, ptr_cb, s->uvlinesize, 9, 9 + field_based,
                             uvsrc_x, uvsrc_y<<field_based, s->h_edge_pos>>1, s->v_edge_pos>>1);
            ff_emulated_edge_mc(uvbuf + 16, ptr_cr, s->uvlinesize, 9, 9 + field_based,
                             uvsrc_x, uvsrc_y<<field_based, s->h_edge_pos>>1, s->v_edge_pos>>1);
            ptr_cb= uvbuf;
            ptr_cr= uvbuf + 16;
        }
    }

    if(!field_based)
        qpix_op[0][dxy](dest_y, ptr_y, linesize);
    else{
        if(bottom_field){
            dest_y += s->linesize;
            dest_cb+= s->uvlinesize;
            dest_cr+= s->uvlinesize;
        }

        if(field_select){
            ptr_y  += s->linesize;
            ptr_cb += s->uvlinesize;
            ptr_cr += s->uvlinesize;
        }
        //damn interlaced mode
        //FIXME boundary mirroring is not exactly correct here
        qpix_op[1][dxy](dest_y  , ptr_y  , linesize);
        qpix_op[1][dxy](dest_y+8, ptr_y+8, linesize);
    }
    if(!ENABLE_GRAY || !(s->flags&CODEC_FLAG_GRAY)){
        pix_op[1][uvdxy](dest_cr, ptr_cr, uvlinesize, h >> 1);
        pix_op[1][uvdxy](dest_cb, ptr_cb, uvlinesize, h >> 1);
    }
}

/**
 * h263 chroma 4mv motion compensation.
 */
static inline void chroma_4mv_motion(MpegEncContext *s,
                                     uint8_t *dest_cb, uint8_t *dest_cr,
                                     uint8_t **ref_picture,
                                     op_pixels_func *pix_op,
                                     int mx, int my){
    int dxy, emu=0, src_x, src_y, offset;
    uint8_t *ptr;

    /* In case of 8X8, we construct a single chroma motion vector
       with a special rounding */
    mx= ff_h263_round_chroma(mx);
    my= ff_h263_round_chroma(my);

    dxy = ((my & 1) << 1) | (mx & 1);
    mx >>= 1;
    my >>= 1;

    src_x = s->mb_x * 8 + mx;
    src_y = s->mb_y * 8 + my;
    src_x = av_clip(src_x, -8, s->width/2);
    if (src_x == s->width/2)
        dxy &= ~1;
    src_y = av_clip(src_y, -8, s->height/2);
    if (src_y == s->height/2)
        dxy &= ~2;

    offset = (src_y * (s->uvlinesize)) + src_x;
    ptr = ref_picture[1] + offset;
    if(s->flags&CODEC_FLAG_EMU_EDGE){
        if(   (unsigned)src_x > (s->h_edge_pos>>1) - (dxy &1) - 8
           || (unsigned)src_y > (s->v_edge_pos>>1) - (dxy>>1) - 8){
            ff_emulated_edge_mc(s->edge_emu_buffer, ptr, s->uvlinesize, 9, 9, src_x, src_y, s->h_edge_pos>>1, s->v_edge_pos>>1);