init_get_bits(&s->gb, s->bitstream_buf, 8*(bytestream2_get_bytes_left(&gb)));
for (s->mb_y=0; s->mb_y < (avctx->height+15)/16; s->mb_y++)
init_get_bits(&s->gb, s->bitstream_buf, 8*(bytestream2_get_bytes_left(&gb)));
for (s->mb_y=0; s->mb_y < (avctx->height+15)/16; s->mb_y++)