const uint8_t *p = av_packet_get_side_data(avpkt, AV_PKT_DATA_SUBTITLE_POSITION, &size);
FFASSDecoderContext *s = avctx->priv_data;
const uint8_t *p = av_packet_get_side_data(avpkt, AV_PKT_DATA_SUBTITLE_POSITION, &size);
FFASSDecoderContext *s = avctx->priv_data;