libavformat/supdec.c

   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 "demux.h"
  21 #include "internal.h"
  22 #include "libavutil/intreadwrite.h"
  23
  24 #define SUP_PGS_MAGIC 0x5047 /* "PG", big endian */
  25
  26 static int sup_read_header(AVFormatContext *s)
  27 {
  28     AVStream *st = avformat_new_stream(s, NULL);
  29     if (!st)
  30         return AVERROR(ENOMEM);
  31     st->codecpar->codec_type = AVMEDIA_TYPE_SUBTITLE;
  32     st->codecpar->codec_id = AV_CODEC_ID_HDMV_PGS_SUBTITLE;
  33     avpriv_set_pts_info(st, 32, 1, 90000);
  34
  35     return 0;
  36 }
  37
  38 static int sup_read_packet(AVFormatContext *s, AVPacket *pkt)
  39 {
  40     int64_t pts, dts, pos;
  41     int ret;
  42
  43     pos = avio_tell(s->pb);
  44
  45     if (avio_rb16(s->pb) != SUP_PGS_MAGIC)
  46         return avio_feof(s->pb) ? AVERROR_EOF : AVERROR_INVALIDDATA;
  47
  48     pts = avio_rb32(s->pb);
  49     dts = avio_rb32(s->pb);
  50
  51     if ((ret = av_get_packet(s->pb, pkt, 3)) < 0)
  52         return ret;
  53
  54     pkt->stream_index = 0;
  55     pkt->flags |= AV_PKT_FLAG_KEY;
  56     pkt->pos = pos;
  57     pkt->pts = pts;
  58     // Many files have DTS set to 0 for all packets, so assume 0 means unset.
  59     pkt->dts = dts ? dts : AV_NOPTS_VALUE;
  60
  61     if (pkt->size >= 3) {
  62         // The full packet size is stored as part of the packet.
  63         size_t len = AV_RB16(pkt->data + 1);
  64
  65         if ((ret = av_append_packet(s->pb, pkt, len)) < 0)
  66             return ret;
  67     }
  68
  69     return 0;
  70 }
  71
  72 static int sup_probe(const AVProbeData *p)
  73 {
  74     unsigned char *buf = p->buf;
  75     size_t buf_size = p->buf_size;
  76     int nb_packets;
  77
  78     for (nb_packets = 0; nb_packets < 10; nb_packets++) {
  79         size_t full_packet_size;
  80         if (buf_size < 10 + 3)
  81             break;
  82         if (AV_RB16(buf) != SUP_PGS_MAGIC)
  83             return 0;
  84         full_packet_size = AV_RB16(buf + 10 + 1) + 10 + 3;
  85         if (buf_size < full_packet_size)
  86             break;
  87         buf += full_packet_size;
  88         buf_size -= full_packet_size;
  89     }
  90     if (!nb_packets)
  91         return 0;
  92     if (nb_packets < 2)
  93         return AVPROBE_SCORE_RETRY / 2;
  94     if (nb_packets < 4)
  95         return AVPROBE_SCORE_RETRY;
  96     if (nb_packets < 10)
  97         return AVPROBE_SCORE_EXTENSION;
  98     return AVPROBE_SCORE_MAX;
  99 }
 100
 101 const FFInputFormat ff_sup_demuxer = {
 102     .p.name         = "sup",
 103     .p.long_name    = NULL_IF_CONFIG_SMALL("raw HDMV Presentation Graphic Stream subtitles"),
 104     .p.extensions   = "sup",
 105     .p.mime_type    = "application/x-pgs",
 106     .p.flags        = AVFMT_GENERIC_INDEX,
 107     .read_probe     = sup_probe,
 108     .read_header    = sup_read_header,
 109     .read_packet    = sup_read_packet,
 110 };