/*
  * This file is part of FFmpeg.
  *
  * FFmpeg is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Lesser General Public
  * License as published by the Free Software Foundation; either
  * version 2.1 of the License, or (at your option) any later version.
  *
  * FFmpeg is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  * Lesser General Public License for more details.
  *
  * You should have received a copy of the GNU Lesser General Public
  * License along with FFmpeg; if not, write to the Free Software
  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  */
 
 #include "avformat.h"
 #include "internal.h"
 #include "libavutil/intreadwrite.h"
 
 #define SUP_PGS_MAGIC 0x5047 /* "PG", big endian */
 
 static int sup_read_header(AVFormatContext *s)
 {
     AVStream *st = avformat_new_stream(s, NULL);
     if (!st)
         return AVERROR(ENOMEM);
     st->codec->codec_type = AVMEDIA_TYPE_SUBTITLE;
     st->codec->codec_id = AV_CODEC_ID_HDMV_PGS_SUBTITLE;
     avpriv_set_pts_info(st, 32, 1, 90000);
 
     return 0;
 }
 
 static int sup_read_packet(AVFormatContext *s, AVPacket *pkt)
 {
     int64_t pts, dts, pos;
     int ret;
 
     pos = avio_tell(s->pb);
 
     if (avio_rb16(s->pb) != SUP_PGS_MAGIC)
         return avio_feof(s->pb) ? AVERROR_EOF : AVERROR_INVALIDDATA;
 
     pts = avio_rb32(s->pb);
     dts = avio_rb32(s->pb);
 
     if ((ret = av_get_packet(s->pb, pkt, 3)) < 0)
         return ret;
 
     pkt->stream_index = 0;
     pkt->flags |= AV_PKT_FLAG_KEY;
     pkt->pos = pos;
     pkt->pts = pts;
     // Many files have DTS set to 0 for all packets, so assume 0 means unset.
     pkt->dts = dts ? dts : AV_NOPTS_VALUE;
 
     if (pkt->size >= 3) {
         // The full packet size is stored as part of the packet.
         size_t len = AV_RB16(pkt->data + 1);
 
         if ((ret = av_append_packet(s->pb, pkt, len)) < 0)
             return ret;
     }
 
     return 0;
 }
 
 static int sup_probe(AVProbeData *p)
 {
     unsigned char *buf = p->buf;
     size_t buf_size = p->buf_size;
     int nb_packets;
 
     for (nb_packets = 0; nb_packets < 10; nb_packets++) {
         size_t full_packet_size;
         if (buf_size < 10 + 3)
             break;
         if (AV_RB16(buf) != SUP_PGS_MAGIC)
             return 0;
         full_packet_size = AV_RB16(buf + 10 + 1) + 10 + 3;
         if (buf_size < full_packet_size)
             break;
         buf += full_packet_size;
         buf_size -= full_packet_size;
     }
     if (!nb_packets)
         return 0;
     if (nb_packets < 2)
         return AVPROBE_SCORE_RETRY / 2;
     if (nb_packets < 4)
         return AVPROBE_SCORE_RETRY;
     if (nb_packets < 10)
         return AVPROBE_SCORE_EXTENSION;
     return AVPROBE_SCORE_MAX;
 }
 
 AVInputFormat ff_sup_demuxer = {
     .name           = "sup",
     .long_name      = NULL_IF_CONFIG_SMALL("raw HDMV Presentation Graphic Stream subtitles"),
     .extensions     = "sup",
     .mime_type      = "application/x-pgs",
     .read_probe     = sup_probe,
     .read_header    = sup_read_header,
     .read_packet    = sup_read_packet,
     .flags          = AVFMT_GENERIC_INDEX,
 };