avctx->pix_fmt= PIX_FMT_YUV420P;
static int decode_init(AVCodecContext *avctx){    SnowContext *s = avctx->priv_data;    int block_size;    common_init(avctx);        block_size = MB_SIZE >> s->block_max_depth;    slice_buffer_init(&s->sb, s->plane[0].height, (block_size) + (s->spatial_decomposition_count * (s->spatial_decomposition_count + 2)) + 1, s->plane[0].width, s->spatial_dwt_buffer);        return 0;}