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srtenc.c
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1 /*
2  * SubRip subtitle muxer
3  * Copyright (c) 2012 Nicolas George <nicolas.george@normalesup.org>
4  *
5  * This file is part of FFmpeg.
6  *
7  * FFmpeg is free software; you can redistribute it and/or
8  * modify it under the terms of the GNU Lesser General Public
9  * License as published by the Free Software Foundation; either
10  * version 2.1 of the License, or (at your option) any later version.
11  *
12  * FFmpeg is distributed in the hope that it will be useful,
13  * but WITHOUT ANY WARRANTY; without even the implied warranty of
14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
15  * Lesser General Public License for more details.
16  *
17  * You should have received a copy of the GNU Lesser General Public
18  * License along with FFmpeg; if not, write to the Free Software
19  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
20  */
21 
22 #include "avformat.h"
23 #include "internal.h"
24 #include "libavutil/log.h"
25 #include "libavutil/intreadwrite.h"
26 
27 /* TODO: add options for:
28  - character encoding;
29  - LF / CRLF;
30  - byte order mark.
31  */
32 
33 typedef struct SRTContext{
34  unsigned index;
35 } SRTContext;
36 
38 {
39  SRTContext *srt = avf->priv_data;
40 
41  if (avf->nb_streams != 1 ||
43  av_log(avf, AV_LOG_ERROR,
44  "SRT supports only a single subtitles stream.\n");
45  return AVERROR(EINVAL);
46  }
47  if (avf->streams[0]->codec->codec_id != AV_CODEC_ID_TEXT &&
49  avf->streams[0]->codec->codec_id != AV_CODEC_ID_SRT) {
50  av_log(avf, AV_LOG_ERROR,
51  "Unsupported subtitles codec: %s\n",
53  return AVERROR(EINVAL);
54  }
55  avpriv_set_pts_info(avf->streams[0], 64, 1, 1000);
56  srt->index = 1;
57  return 0;
58 }
59 
61 {
62  SRTContext *srt = avf->priv_data;
63  int write_ts = avf->streams[0]->codec->codec_id != AV_CODEC_ID_SRT;
64 
65  if (write_ts) {
66  int64_t s = pkt->pts, e, d = pkt->duration;
67  int size, x1 = -1, y1 = -1, x2 = -1, y2 = -1;
68  const uint8_t *p;
69 
71  if (p && size == 16) {
72  x1 = AV_RL32(p );
73  y1 = AV_RL32(p + 4);
74  x2 = AV_RL32(p + 8);
75  y2 = AV_RL32(p + 12);
76  }
77 
78  if (d <= 0)
79  /* For backward compatibility, fallback to convergence_duration. */
80  d = pkt->convergence_duration;
81  if (s == AV_NOPTS_VALUE || d < 0) {
83  "Insufficient timestamps in event number %d.\n", srt->index);
84  return 0;
85  }
86  e = s + d;
87  avio_printf(avf->pb, "%d\n%02d:%02d:%02d,%03d --> %02d:%02d:%02d,%03d",
88  srt->index,
89  (int)(s / 3600000), (int)(s / 60000) % 60,
90  (int)(s / 1000) % 60, (int)(s % 1000),
91  (int)(e / 3600000), (int)(e / 60000) % 60,
92  (int)(e / 1000) % 60, (int)(e % 1000));
93  if (p)
94  avio_printf(avf->pb, " X1:%03d X2:%03d Y1:%03d Y2:%03d",
95  x1, x2, y1, y2);
96  avio_printf(avf->pb, "\n");
97  }
98  avio_write(avf->pb, pkt->data, pkt->size);
99  if (write_ts)
100  avio_write(avf->pb, "\n\n", 2);
101  srt->index++;
102  return 0;
103 }
104 
106  .name = "srt",
107  .long_name = NULL_IF_CONFIG_SMALL("SubRip subtitle"),
108  .mime_type = "application/x-subrip",
109  .extensions = "srt",
110  .priv_data_size = sizeof(SRTContext),
114  .subtitle_codec = AV_CODEC_ID_SUBRIP,
115 };