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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.  
  37. static 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.  
  60. static 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.  
  105. AVOutputFormat 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.