if(s->pict_type==B_TYPE || (!s->has_b_frames)){
if(s->pict_type==B_TYPE || s->low_delay){
void ff_draw_horiz_band(MpegEncContext *s){    if (    s->avctx->draw_horiz_band         && (s->num_available_buffers>=1 || (!s->has_b_frames)) ) {        UINT8 *src_ptr[3];        int y, h, offset;        y = s->mb_y * 16;        h = s->height - y;        if (h > 16)            h = 16;        if(s->pict_type==B_TYPE)            offset = 0;        else            offset = y * s->linesize;        if(s->pict_type==B_TYPE || (!s->has_b_frames)){            src_ptr[0] = s->current_picture.data[0] + offset;            src_ptr[1] = s->current_picture.data[1] + (offset >> 2);            src_ptr[2] = s->current_picture.data[2] + (offset >> 2);        } else {            src_ptr[0] = s->last_picture.data[0] + offset;            src_ptr[1] = s->last_picture.data[1] + (offset >> 2);            src_ptr[2] = s->last_picture.data[2] + (offset >> 2);        }        emms_c();        s->avctx->draw_horiz_band(s->avctx, src_ptr, s->linesize,                               y, s->width, h);    }}