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  1. /*
  2.  * MicroDVD subtitle demuxer
  3.  * Copyright (c) 2010  Aurelien Jacobs <aurel@gnuage.org>
  4.  * Copyright (c) 2012  Clément Bœsch <u pkh me>
  5.  *
  6.  * This file is part of FFmpeg.
  7.  *
  8.  * FFmpeg is free software; you can redistribute it and/or
  9.  * modify it under the terms of the GNU Lesser General Public
  10.  * License as published by the Free Software Foundation; either
  11.  * version 2.1 of the License, or (at your option) any later version.
  12.  *
  13.  * FFmpeg is distributed in the hope that it will be useful,
  14.  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  15.  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  16.  * Lesser General Public License for more details.
  17.  *
  18.  * You should have received a copy of the GNU Lesser General Public
  19.  * License along with FFmpeg; if not, write to the Free Software
  20.  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  21.  */
  22.  
  23. #include "avformat.h"
  24. #include "internal.h"
  25. #include "subtitles.h"
  26. #include "libavutil/intreadwrite.h"
  27. #include "libavutil/opt.h"
  28.  
  29. #define MAX_LINESIZE 2048
  30.  
  31.  
  32. typedef struct {
  33.     const AVClass *class;
  34.     FFDemuxSubtitlesQueue q;
  35.     AVRational frame_rate;
  36. } MicroDVDContext;
  37.  
  38.  
  39. static int microdvd_probe(AVProbeData *p)
  40. {
  41.     unsigned char c;
  42.     const uint8_t *ptr = p->buf;
  43.     int i;
  44.  
  45.     if (AV_RB24(ptr) == 0xEFBBBF)
  46.         ptr += 3;  /* skip UTF-8 BOM */
  47.  
  48.     for (i=0; i<3; i++) {
  49.         if (sscanf(ptr, "{%*d}{}%c",     &c) != 1 &&
  50.             sscanf(ptr, "{%*d}{%*d}%c",  &c) != 1 &&
  51.             sscanf(ptr, "{DEFAULT}{}%c", &c) != 1)
  52.             return 0;
  53.         ptr += ff_subtitles_next_line(ptr);
  54.     }
  55.     return AVPROBE_SCORE_MAX;
  56. }
  57.  
  58. static int64_t get_pts(const char *buf)
  59. {
  60.     int frame;
  61.     char c;
  62.  
  63.     if (sscanf(buf, "{%d}{%c", &frame, &c) == 2)
  64.         return frame;
  65.     return AV_NOPTS_VALUE;
  66. }
  67.  
  68. static int get_duration(const char *buf)
  69. {
  70.     int frame_start, frame_end;
  71.  
  72.     if (sscanf(buf, "{%d}{%d}", &frame_start, &frame_end) == 2)
  73.         return frame_end - frame_start;
  74.     return -1;
  75. }
  76.  
  77. static const char *bom = "\xEF\xBB\xBF";
  78.  
  79. static int microdvd_read_header(AVFormatContext *s)
  80. {
  81.     AVRational pts_info = (AVRational){ 2997, 125 };  /* default: 23.976 fps */
  82.     MicroDVDContext *microdvd = s->priv_data;
  83.     AVStream *st = avformat_new_stream(s, NULL);
  84.     int i = 0;
  85.     char line_buf[MAX_LINESIZE];
  86.     int has_real_fps = 0;
  87.  
  88.     if (!st)
  89.         return AVERROR(ENOMEM);
  90.  
  91.     while (!avio_feof(s->pb)) {
  92.         char *p;
  93.         AVPacket *sub;
  94.         int64_t pos = avio_tell(s->pb);
  95.         int len = ff_get_line(s->pb, line_buf, sizeof(line_buf));
  96.         char *line = line_buf;
  97.  
  98.         if (!strncmp(line, bom, 3))
  99.             line += 3;
  100.         p = line;
  101.  
  102.         if (!len)
  103.             break;
  104.         line[strcspn(line, "\r\n")] = 0;
  105.         if (i++ < 3) {
  106.             int frame;
  107.             double fps;
  108.             char c;
  109.  
  110.             if ((sscanf(line, "{%d}{}%6lf",    &frame, &fps) == 2 ||
  111.                  sscanf(line, "{%d}{%*d}%6lf", &frame, &fps) == 2)
  112.                 && frame <= 1 && fps > 3 && fps < 100) {
  113.                 pts_info = av_d2q(fps, 100000);
  114.                 has_real_fps = 1;
  115.                 continue;
  116.             }
  117.             if (!st->codec->extradata && sscanf(line, "{DEFAULT}{}%c", &c) == 1) {
  118.                 st->codec->extradata = av_strdup(line + 11);
  119.                 if (!st->codec->extradata)
  120.                     return AVERROR(ENOMEM);
  121.                 st->codec->extradata_size = strlen(st->codec->extradata) + 1;
  122.                 continue;
  123.             }
  124.         }
  125. #define SKIP_FRAME_ID                                       \
  126.     p = strchr(p, '}');                                     \
  127.     if (!p) {                                               \
  128.         av_log(s, AV_LOG_WARNING, "Invalid event \"%s\""    \
  129.                " at line %d\n", line, i);                   \
  130.         continue;                                           \
  131.     }                                                       \
  132.     p++
  133.         SKIP_FRAME_ID;
  134.         SKIP_FRAME_ID;
  135.         if (!*p)
  136.             continue;
  137.         sub = ff_subtitles_queue_insert(&microdvd->q, p, strlen(p), 0);
  138.         if (!sub)
  139.             return AVERROR(ENOMEM);
  140.         sub->pos = pos;
  141.         sub->pts = get_pts(line);
  142.         sub->duration = get_duration(line);
  143.     }
  144.     ff_subtitles_queue_finalize(&microdvd->q);
  145.     if (has_real_fps) {
  146.         /* export the FPS info only if set in the file */
  147.         microdvd->frame_rate = pts_info;
  148.     } else if (microdvd->frame_rate.num) {
  149.         /* fallback on user specified frame rate */
  150.         pts_info = microdvd->frame_rate;
  151.     }
  152.     avpriv_set_pts_info(st, 64, pts_info.den, pts_info.num);
  153.     st->codec->codec_type = AVMEDIA_TYPE_SUBTITLE;
  154.     st->codec->codec_id   = AV_CODEC_ID_MICRODVD;
  155.     return 0;
  156. }
  157.  
  158. static int microdvd_read_packet(AVFormatContext *s, AVPacket *pkt)
  159. {
  160.     MicroDVDContext *microdvd = s->priv_data;
  161.     return ff_subtitles_queue_read_packet(&microdvd->q, pkt);
  162. }
  163.  
  164. static int microdvd_read_seek(AVFormatContext *s, int stream_index,
  165.                              int64_t min_ts, int64_t ts, int64_t max_ts, int flags)
  166. {
  167.     MicroDVDContext *microdvd = s->priv_data;
  168.     return ff_subtitles_queue_seek(&microdvd->q, s, stream_index,
  169.                                    min_ts, ts, max_ts, flags);
  170. }
  171.  
  172. static int microdvd_read_close(AVFormatContext *s)
  173. {
  174.     MicroDVDContext *microdvd = s->priv_data;
  175.     ff_subtitles_queue_clean(&microdvd->q);
  176.     return 0;
  177. }
  178.  
  179.  
  180. #define OFFSET(x) offsetof(MicroDVDContext, x)
  181. #define SD AV_OPT_FLAG_SUBTITLE_PARAM|AV_OPT_FLAG_DECODING_PARAM
  182. static const AVOption microdvd_options[] = {
  183.     { "subfps", "set the movie frame rate fallback", OFFSET(frame_rate), AV_OPT_TYPE_RATIONAL, {.dbl=0}, 0, INT_MAX, SD },
  184.     { NULL }
  185. };
  186.  
  187. static const AVClass microdvd_class = {
  188.     .class_name = "microdvddec",
  189.     .item_name  = av_default_item_name,
  190.     .option     = microdvd_options,
  191.     .version    = LIBAVUTIL_VERSION_INT,
  192. };
  193.  
  194. AVInputFormat ff_microdvd_demuxer = {
  195.     .name           = "microdvd",
  196.     .long_name      = NULL_IF_CONFIG_SMALL("MicroDVD subtitle format"),
  197.     .priv_data_size = sizeof(MicroDVDContext),
  198.     .read_probe     = microdvd_probe,
  199.     .read_header    = microdvd_read_header,
  200.     .read_packet    = microdvd_read_packet,
  201.     .read_seek2     = microdvd_read_seek,
  202.     .read_close     = microdvd_read_close,
  203.     .priv_class     = &microdvd_class,
  204. };
  205.