static void init_block_index(VC1Context *v)
{
    MpegEncContext *s = &v->s;
    ff_init_block_index(s);
    if (v->field_mode && !(v->second_field ^ v->tff)) {
        s->dest[0] += s->current_picture_ptr->f->linesize[0];
        s->dest[1] += s->current_picture_ptr->f->linesize[1];
        s->dest[2] += s->current_picture_ptr->f->linesize[2];
    }
}