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supdec.c
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1 /*
2  * This file is part of FFmpeg.
3  *
4  * FFmpeg is free software; you can redistribute it and/or
5  * modify it under the terms of the GNU Lesser General Public
6  * License as published by the Free Software Foundation; either
7  * version 2.1 of the License, or (at your option) any later version.
8  *
9  * FFmpeg is distributed in the hope that it will be useful,
10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
12  * Lesser General Public License for more details.
13  *
14  * You should have received a copy of the GNU Lesser General Public
15  * License along with FFmpeg; if not, write to the Free Software
16  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
17  */
18 
19 #include "avformat.h"
20 #include "internal.h"
21 #include "libavutil/intreadwrite.h"
22 
23 #define SUP_PGS_MAGIC 0x5047 /* "PG", big endian */
24 
26 {
28  if (!st)
29  return AVERROR(ENOMEM);
32  avpriv_set_pts_info(st, 32, 1, 90000);
33 
34  return 0;
35 }
36 
38 {
39  int64_t pts, dts, pos;
40  int ret;
41 
42  pos = avio_tell(s->pb);
43 
44  if (avio_rb16(s->pb) != SUP_PGS_MAGIC)
46 
47  pts = avio_rb32(s->pb);
48  dts = avio_rb32(s->pb);
49 
50  if ((ret = av_get_packet(s->pb, pkt, 3)) < 0)
51  return ret;
52 
53  pkt->stream_index = 0;
54  pkt->flags |= AV_PKT_FLAG_KEY;
55  pkt->pos = pos;
56  pkt->pts = pts;
57  // Many files have DTS set to 0 for all packets, so assume 0 means unset.
58  pkt->dts = dts ? dts : AV_NOPTS_VALUE;
59 
60  if (pkt->size >= 3) {
61  // The full packet size is stored as part of the packet.
62  size_t len = AV_RB16(pkt->data + 1);
63 
64  if ((ret = av_append_packet(s->pb, pkt, len)) < 0)
65  return ret;
66  }
67 
68  return 0;
69 }
70 
71 static int sup_probe(AVProbeData *p)
72 {
73  unsigned char *buf = p->buf;
74  size_t buf_size = p->buf_size;
75  int nb_packets;
76 
77  for (nb_packets = 0; nb_packets < 10; nb_packets++) {
78  size_t full_packet_size;
79  if (buf_size < 10 + 3)
80  break;
81  if (AV_RB16(buf) != SUP_PGS_MAGIC)
82  return 0;
83  full_packet_size = AV_RB16(buf + 10 + 1) + 10 + 3;
84  if (buf_size < full_packet_size)
85  break;
86  buf += full_packet_size;
87  buf_size -= full_packet_size;
88  }
89  if (!nb_packets)
90  return 0;
91  if (nb_packets < 2)
92  return AVPROBE_SCORE_RETRY / 2;
93  if (nb_packets < 4)
94  return AVPROBE_SCORE_RETRY;
95  if (nb_packets < 10)
97  return AVPROBE_SCORE_MAX;
98 }
99 
101  .name = "sup",
102  .long_name = NULL_IF_CONFIG_SMALL("raw HDMV Presentation Graphic Stream subtitles"),
103  .extensions = "sup",
104  .mime_type = "application/x-pgs",
105  .read_probe = sup_probe,
106  .read_header = sup_read_header,
107  .read_packet = sup_read_packet,
108  .flags = AVFMT_GENERIC_INDEX,
109 };