libavformat/mpl2dec.c

   1 /*
   2  * Copyright (c) 2012 Clément Bœsch
   3  *
   4  * This file is part of FFmpeg.
   5  *
   6  * FFmpeg is free software; you can redistribute it and/or
   7  * modify it under the terms of the GNU Lesser General Public
   8  * License as published by the Free Software Foundation; either
   9  * version 2.1 of the License, or (at your option) any later version.
  10  *
  11  * FFmpeg is distributed in the hope that it will be useful,
  12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14  * Lesser General Public License for more details.
  15  *
  16  * You should have received a copy of the GNU Lesser General Public
  17  * License along with FFmpeg; if not, write to the Free Software
  18  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  19  */
  20
  21 /**
  22  * @file
  23  * MPL2 subtitles format demuxer
  24  */
  25
  26 #include "libavutil/intreadwrite.h"
  27
  28 #include "avformat.h"
  29 #include "demux.h"
  30 #include "internal.h"
  31 #include "subtitles.h"
  32
  33 typedef struct {
  34     FFDemuxSubtitlesQueue q;
  35 } MPL2Context;
  36
  37 static int mpl2_probe(const AVProbeData *p)
  38 {
  39     int i;
  40     char c;
  41     int64_t start, end;
  42     const unsigned char *ptr = p->buf;
  43     const unsigned char *ptr_end = ptr + p->buf_size;
  44
  45     if (AV_RB24(ptr) == 0xefbbbf)
  46         ptr += 3;
  47
  48     for (i = 0; i < 2; i++) {
  49         if (sscanf(ptr, "[%"SCNd64"][%"SCNd64"]%c", &start, &end, &c) != 3 &&
  50             sscanf(ptr, "[%"SCNd64"][]%c",          &start,       &c) != 2)
  51             return 0;
  52         ptr += ff_subtitles_next_line(ptr);
  53         if (ptr >= ptr_end)
  54             return 0;
  55     }
  56     return AVPROBE_SCORE_MAX;
  57 }
  58
  59 static int read_ts(char **line, int64_t *pts_start, int64_t *duration)
  60 {
  61     char c;
  62     int len;
  63     int64_t end;
  64
  65     if (sscanf(*line, "[%"SCNd64"][]%c%n",
  66                pts_start, &c, &len) >= 2) {
  67         *duration = -1;
  68         *line += len - 1;
  69         return 0;
  70     }
  71     if (sscanf(*line, "[%"SCNd64"][%"SCNd64"]%c%n",
  72                pts_start, &end, &c, &len) >= 3) {
  73         if (end < *pts_start || end - (uint64_t)*pts_start > INT64_MAX) {
  74             *duration = -1;
  75         } else
  76             *duration = end - *pts_start;
  77         *line += len - 1;
  78         return 0;
  79     }
  80     return -1;
  81 }
  82
  83 static int mpl2_read_header(AVFormatContext *s)
  84 {
  85     MPL2Context *mpl2 = s->priv_data;
  86     AVStream *st = avformat_new_stream(s, NULL);
  87
  88     if (!st)
  89         return AVERROR(ENOMEM);
  90     avpriv_set_pts_info(st, 64, 1, 10);
  91     st->codecpar->codec_type = AVMEDIA_TYPE_SUBTITLE;
  92     st->codecpar->codec_id   = AV_CODEC_ID_MPL2;
  93
  94     if (avio_rb24(s->pb) != 0xefbbbf)
  95         avio_seek(s->pb, -3, SEEK_CUR);
  96
  97     while (!avio_feof(s->pb)) {
  98         char line[4096];
  99         char *p = line;
 100         const int64_t pos = avio_tell(s->pb);
 101         int len = ff_get_line(s->pb, line, sizeof(line));
 102         int64_t pts_start;
 103         int64_t duration;
 104
 105         if (!len)
 106             break;
 107
 108         line[strcspn(line, "\r\n")] = 0;
 109
 110         if (!read_ts(&p, &pts_start, &duration)) {
 111             AVPacket *sub;
 112
 113             sub = ff_subtitles_queue_insert(&mpl2->q, p, strlen(p), 0);
 114             if (!sub)
 115                 return AVERROR(ENOMEM);
 116             sub->pos = pos;
 117             sub->pts = pts_start;
 118             sub->duration = duration;
 119         }
 120     }
 121
 122     ff_subtitles_queue_finalize(s, &mpl2->q);
 123     return 0;
 124 }
 125
 126 const FFInputFormat ff_mpl2_demuxer = {
 127     .p.name         = "mpl2",
 128     .p.long_name    = NULL_IF_CONFIG_SMALL("MPL2 subtitles"),
 129     .p.extensions   = "txt,mpl2",
 130     .priv_data_size = sizeof(MPL2Context),
 131     .flags_internal = FF_INFMT_FLAG_INIT_CLEANUP,
 132     .read_probe     = mpl2_probe,
 133     .read_header    = mpl2_read_header,
 134     .read_packet    = ff_subtitles_read_packet,
 135     .read_seek2     = ff_subtitles_read_seek,
 136     .read_close     = ff_subtitles_read_close,
 137 };