/* image descriptor byte: origin is always top-left, bits 0-3 specify alpha */
pkt->data[17] = 0x20 | (avctx->pix_fmt == PIX_FMT_BGRA ? 8 : 0);
/* image descriptor byte: origin is always top-left, bits 0-3 specify alpha */
pkt->data[17] = 0x20 | (avctx->pix_fmt == PIX_FMT_BGRA ? 8 : 0);