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
33typedef struct SRTContext{
34    unsigned index;
35} SRTContext;
36
37static int srt_write_header(AVFormatContext *avf)
38{
39    SRTContext *srt = avf->priv_data;
40
41    if (avf->nb_streams != 1 ||
42        avf->streams[0]->codec->codec_type != AVMEDIA_TYPE_SUBTITLE) {
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 &&
48        avf->streams[0]->codec->codec_id != AV_CODEC_ID_SUBRIP &&
49        avf->streams[0]->codec->codec_id != AV_CODEC_ID_SRT) {
50        av_log(avf, AV_LOG_ERROR,
51               "Unsupported subtitles codec: %s\n",
52               avcodec_get_name(avf->streams[0]->codec->codec_id));
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
60static int srt_write_packet(AVFormatContext *avf, AVPacket *pkt)
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
70        p = av_packet_get_side_data(pkt, AV_PKT_DATA_SUBTITLE_POSITION, &size);
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) {
82            av_log(avf, AV_LOG_WARNING,
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
105AVOutputFormat ff_srt_muxer = {
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),
111    .write_header   = srt_write_header,
112    .write_packet   = srt_write_packet,
113    .flags          = AVFMT_VARIABLE_FPS | AVFMT_TS_NONSTRICT,
114    .subtitle_codec = AV_CODEC_ID_SUBRIP,
115};
116