libavformat/ffmetadec.c

   1 /*
   2  * Metadata demuxer
   3  * Copyright (c) 2010 Anton Khirnov
   4  *
   5  * This file is part of Libav.
   6  *
   7  * Libav 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  * Libav 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 Libav; if not, write to the Free Software
  19  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  20  */
  21
  22 #include "libavutil/mathematics.h"
  23 #include "avformat.h"
  24 #include "ffmeta.h"
  25 #include "internal.h"
  26 #include "libavutil/dict.h"
  27
  28 static int probe(AVProbeData *p)
  29 {
  30     if(!memcmp(p->buf, ID_STRING, strlen(ID_STRING)))
  31         return AVPROBE_SCORE_MAX;
  32     return 0;
  33 }
  34
  35 static void get_line(AVIOContext *s, uint8_t *buf, int size)
  36 {
  37     do {
  38         uint8_t c;
  39         int i = 0;
  40
  41         while ((c = avio_r8(s))) {
  42             if (c == '\\') {
  43                 if (i < size - 1)
  44                     buf[i++] = c;
  45                 c = avio_r8(s);
  46             } else if (c == '\n')
  47                 break;
  48
  49             if (i < size - 1)
  50                 buf[i++] = c;
  51         }
  52         buf[i] = 0;
  53     } while (!s->eof_reached && (buf[0] == ';' || buf[0] == '#' || buf[0] == 0));
  54 }
  55
  56 static AVChapter *read_chapter(AVFormatContext *s)
  57 {
  58     uint8_t line[256];
  59     int64_t start, end;
  60     AVRational tb = {1, 1e9};
  61
  62     get_line(s->pb, line, sizeof(line));
  63
  64     if (sscanf(line, "TIMEBASE=%d/%d", &tb.num, &tb.den))
  65         get_line(s->pb, line, sizeof(line));
  66     if (!sscanf(line, "START=%"SCNd64, &start)) {
  67         av_log(s, AV_LOG_ERROR, "Expected chapter start timestamp, found %s.\n", line);
  68         start = (s->nb_chapters && s->chapters[s->nb_chapters - 1]->end != AV_NOPTS_VALUE) ?
  69                  s->chapters[s->nb_chapters - 1]->end : 0;
  70     } else
  71         get_line(s->pb, line, sizeof(line));
  72
  73     if (!sscanf(line, "END=%"SCNd64, &end)) {
  74         av_log(s, AV_LOG_ERROR, "Expected chapter end timestamp, found %s.\n", line);
  75         end = AV_NOPTS_VALUE;
  76     }
  77
  78     return avpriv_new_chapter(s, s->nb_chapters, tb, start, end, NULL);
  79 }
  80
  81 static uint8_t *unescape(uint8_t *buf, int size)
  82 {
  83     uint8_t *ret = av_malloc(size + 1);
  84     uint8_t *p1  = ret, *p2 = buf;
  85
  86     if (!ret)
  87         return NULL;
  88
  89     while (p2 < buf + size) {
  90         if (*p2 == '\\')
  91             p2++;
  92         *p1++ = *p2++;
  93     }
  94     *p1 = 0;
  95     return ret;
  96 }
  97
  98 static int read_tag(uint8_t *line, AVDictionary **m)
  99 {
 100     uint8_t *key, *value, *p = line;
 101
 102     /* find first not escaped '=' */
 103     while (1) {
 104         if (*p == '=')
 105             break;
 106         else if (*p == '\\')
 107             p++;
 108
 109         if (*p++)
 110             continue;
 111
 112         return 0;
 113     }
 114
 115     if (!(key = unescape(line, p - line)))
 116         return AVERROR(ENOMEM);
 117     if (!(value = unescape(p + 1, strlen(p + 1)))) {
 118         av_free(key);
 119         return AVERROR(ENOMEM);
 120     }
 121
 122     av_dict_set(m, key, value, AV_DICT_DONT_STRDUP_KEY | AV_DICT_DONT_STRDUP_VAL);
 123     return 0;
 124 }
 125
 126 static int read_header(AVFormatContext *s)
 127 {
 128     AVDictionary **m = &s->metadata;
 129     uint8_t line[1024];
 130
 131     while(!s->pb->eof_reached) {
 132         get_line(s->pb, line, sizeof(line));
 133
 134         if (!memcmp(line, ID_STREAM, strlen(ID_STREAM))) {
 135             AVStream *st = avformat_new_stream(s, NULL);
 136
 137             if (!st)
 138                 return -1;
 139
 140             st->codec->codec_type = AVMEDIA_TYPE_DATA;
 141             st->codec->codec_id   = AV_CODEC_ID_FFMETADATA;
 142
 143             m = &st->metadata;
 144         } else if (!memcmp(line, ID_CHAPTER, strlen(ID_CHAPTER))) {
 145             AVChapter *ch = read_chapter(s);
 146
 147             if (!ch)
 148                 return -1;
 149
 150             m = &ch->metadata;
 151         } else
 152             read_tag(line, m);
 153     }
 154
 155     s->start_time = 0;
 156     if (s->nb_chapters)
 157         s->duration = av_rescale_q(s->chapters[s->nb_chapters - 1]->end,
 158                                    s->chapters[s->nb_chapters - 1]->time_base,
 159                                    AV_TIME_BASE_Q);
 160
 161     return 0;
 162 }
 163
 164 static int read_packet(AVFormatContext *s, AVPacket *pkt)
 165 {
 166     return AVERROR_EOF;
 167 }
 168
 169 AVInputFormat ff_ffmetadata_demuxer = {
 170     .name        = "ffmetadata",
 171     .long_name   = NULL_IF_CONFIG_SMALL("FFmpeg metadata in text"),
 172     .read_probe  = probe,
 173     .read_header = read_header,
 174     .read_packet = read_packet,
 175 };