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  1. /*
  2.  * SubRip subtitle demuxer
  3.  * Copyright (c) 2010  Aurelien Jacobs <aurel@gnuage.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 "subtitles.h"
  25. #include "libavutil/bprint.h"
  26. #include "libavutil/intreadwrite.h"
  27.  
  28. typedef struct {
  29.     FFDemuxSubtitlesQueue q;
  30. } SRTContext;
  31.  
  32. static int srt_probe(AVProbeData *p)
  33. {
  34.     int v;
  35.     char buf[64], *pbuf;
  36.     FFTextReader tr;
  37.  
  38.     ff_text_init_buf(&tr, p->buf, p->buf_size);
  39.  
  40.     while (ff_text_peek_r8(&tr) == '\r' || ff_text_peek_r8(&tr) == '\n')
  41.         ff_text_r8(&tr);
  42.  
  43.     /* Check if the first non-empty line is a number. We do not check what the
  44.      * number is because in practice it can be anything.
  45.      * Also, that number can be followed by random garbage, so we can not
  46.      * unfortunately check that we only have a number. */
  47.     if (ff_subtitles_read_line(&tr, buf, sizeof(buf)) < 0 ||
  48.         strtol(buf, &pbuf, 10) < 0 || pbuf == buf)
  49.         return 0;
  50.  
  51.     /* Check if the next line matches a SRT timestamp */
  52.     if (ff_subtitles_read_line(&tr, buf, sizeof(buf)) < 0)
  53.         return 0;
  54.     if (buf[0] >= '0' && buf[0] <= '9' && strstr(buf, " --> ")
  55.         && sscanf(buf, "%*d:%*2d:%*2d%*1[,.]%*3d --> %*d:%*2d:%*2d%*1[,.]%3d", &v) == 1)
  56.         return AVPROBE_SCORE_MAX;
  57.  
  58.     return 0;
  59. }
  60.  
  61. static int64_t get_pts(const char **buf, int *duration,
  62.                        int32_t *x1, int32_t *y1, int32_t *x2, int32_t *y2)
  63. {
  64.     int i;
  65.  
  66.     for (i=0; i<2; i++) {
  67.         int hh1, mm1, ss1, ms1;
  68.         int hh2, mm2, ss2, ms2;
  69.         if (sscanf(*buf, "%d:%2d:%2d%*1[,.]%3d --> %d:%2d:%2d%*1[,.]%3d"
  70.                    "%*[ ]X1:%u X2:%u Y1:%u Y2:%u",
  71.                    &hh1, &mm1, &ss1, &ms1,
  72.                    &hh2, &mm2, &ss2, &ms2,
  73.                    x1, x2, y1, y2) >= 8) {
  74.             int64_t start = (hh1*3600LL + mm1*60LL + ss1) * 1000LL + ms1;
  75.             int64_t end   = (hh2*3600LL + mm2*60LL + ss2) * 1000LL + ms2;
  76.             *duration = end - start;
  77.             *buf += ff_subtitles_next_line(*buf);
  78.             return start;
  79.         }
  80.         *buf += ff_subtitles_next_line(*buf);
  81.     }
  82.     return AV_NOPTS_VALUE;
  83. }
  84.  
  85. static int srt_read_header(AVFormatContext *s)
  86. {
  87.     SRTContext *srt = s->priv_data;
  88.     AVBPrint buf;
  89.     AVStream *st = avformat_new_stream(s, NULL);
  90.     int res = 0;
  91.     FFTextReader tr;
  92.     ff_text_init_avio(s, &tr, s->pb);
  93.  
  94.     if (!st)
  95.         return AVERROR(ENOMEM);
  96.     avpriv_set_pts_info(st, 64, 1, 1000);
  97.     st->codec->codec_type = AVMEDIA_TYPE_SUBTITLE;
  98.     st->codec->codec_id   = AV_CODEC_ID_SUBRIP;
  99.  
  100.     av_bprint_init(&buf, 0, AV_BPRINT_SIZE_UNLIMITED);
  101.  
  102.     while (!ff_text_eof(&tr)) {
  103.         ff_subtitles_read_text_chunk(&tr, &buf);
  104.  
  105.         if (buf.len) {
  106.             int64_t pos = ff_text_pos(&tr);
  107.             int64_t pts;
  108.             int duration;
  109.             const char *ptr = buf.str;
  110.             int32_t x1 = -1, y1 = -1, x2 = -1, y2 = -1;
  111.             AVPacket *sub;
  112.  
  113.             pts = get_pts(&ptr, &duration, &x1, &y1, &x2, &y2);
  114.             if (pts != AV_NOPTS_VALUE) {
  115.                 int len = buf.len - (ptr - buf.str);
  116.                 if (len <= 0)
  117.                     continue;
  118.                 sub = ff_subtitles_queue_insert(&srt->q, ptr, len, 0);
  119.                 if (!sub) {
  120.                     res = AVERROR(ENOMEM);
  121.                     goto end;
  122.                 }
  123.                 sub->pos = pos;
  124.                 sub->pts = pts;
  125.                 sub->duration = duration;
  126.                 if (x1 != -1) {
  127.                     uint8_t *p = av_packet_new_side_data(sub, AV_PKT_DATA_SUBTITLE_POSITION, 16);
  128.                     if (p) {
  129.                         AV_WL32(p,      x1);
  130.                         AV_WL32(p +  4, y1);
  131.                         AV_WL32(p +  8, x2);
  132.                         AV_WL32(p + 12, y2);
  133.                     }
  134.                 }
  135.             }
  136.         }
  137.     }
  138.  
  139.     ff_subtitles_queue_finalize(&srt->q);
  140.  
  141. end:
  142.     av_bprint_finalize(&buf, NULL);
  143.     return res;
  144. }
  145.  
  146. static int srt_read_packet(AVFormatContext *s, AVPacket *pkt)
  147. {
  148.     SRTContext *srt = s->priv_data;
  149.     return ff_subtitles_queue_read_packet(&srt->q, pkt);
  150. }
  151.  
  152. static int srt_read_seek(AVFormatContext *s, int stream_index,
  153.                          int64_t min_ts, int64_t ts, int64_t max_ts, int flags)
  154. {
  155.     SRTContext *srt = s->priv_data;
  156.     return ff_subtitles_queue_seek(&srt->q, s, stream_index,
  157.                                    min_ts, ts, max_ts, flags);
  158. }
  159.  
  160. static int srt_read_close(AVFormatContext *s)
  161. {
  162.     SRTContext *srt = s->priv_data;
  163.     ff_subtitles_queue_clean(&srt->q);
  164.     return 0;
  165. }
  166.  
  167. AVInputFormat ff_srt_demuxer = {
  168.     .name        = "srt",
  169.     .long_name   = NULL_IF_CONFIG_SMALL("SubRip subtitle"),
  170.     .priv_data_size = sizeof(SRTContext),
  171.     .read_probe  = srt_probe,
  172.     .read_header = srt_read_header,
  173.     .read_packet = srt_read_packet,
  174.     .read_seek2  = srt_read_seek,
  175.     .read_close  = srt_read_close,
  176. };
  177.