libavformat/ffmetadec.c

   1 /*
   2  * Metadata demuxer
   3  * Copyright (c) 2010 Anton Khirnov
   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 "libavutil/bprint.h"
  23 #include "libavutil/mathematics.h"
  24 #include "libavutil/mem.h"
  25 #include "avformat.h"
  26 #include "demux.h"
  27 #include "ffmeta.h"
  28 #include "libavutil/dict.h"
  29
  30 static int probe(const AVProbeData *p)
  31 {
  32     if(!memcmp(p->buf, ID_STRING, strlen(ID_STRING)))
  33         return AVPROBE_SCORE_MAX;
  34     return 0;
  35 }
  36
  37 static int64_t read_line_to_bprint_escaped(AVIOContext *s, AVBPrint *bp)
  38 {
  39     int len, end;
  40     int64_t read = 0;
  41     char tmp[1024];
  42     char c;
  43     char prev = ' ';
  44
  45     do {
  46         len = 0;
  47         do {
  48             c = avio_r8(s);
  49             end = prev != '\\' && (c == '\r' || c == '\n' || c == '\0');
  50             if (!end)
  51                 tmp[len++] = c;
  52             prev = c;
  53         } while (!end && len < sizeof(tmp));
  54         av_bprint_append_data(bp, tmp, len);
  55         read += len;
  56     } while (!end);
  57
  58     if (c == '\r' && avio_r8(s) != '\n' && !avio_feof(s))
  59         avio_skip(s, -1);
  60
  61     if (!c && s->error)
  62         return s->error;
  63
  64     if (!c && !read && avio_feof(s))
  65         return AVERROR_EOF;
  66
  67     return read;
  68 }
  69
  70 static void get_bprint_line(AVIOContext *s, AVBPrint *bp)
  71 {
  72
  73     do {
  74         av_bprint_clear(bp);
  75         read_line_to_bprint_escaped(s, bp);
  76     } while (!avio_feof(s) && (bp->str[0] == ';' || bp->str[0] == '#' || bp->str[0] == 0));
  77 }
  78
  79 static void get_line(AVIOContext *s, uint8_t *buf, int size)
  80 {
  81     do {
  82         uint8_t c;
  83         int i = 0;
  84
  85         while ((c = avio_r8(s))) {
  86             if (c == '\\') {
  87                 if (i < size - 1)
  88                     buf[i++] = c;
  89                 c = avio_r8(s);
  90             } else if (c == '\n')
  91                 break;
  92
  93             if (i < size - 1)
  94                 buf[i++] = c;
  95         }
  96         buf[i] = 0;
  97     } while (!avio_feof(s) && (buf[0] == ';' || buf[0] == '#' || buf[0] == 0));
  98 }
  99
 100 static AVChapter *read_chapter(AVFormatContext *s)
 101 {
 102     uint8_t line[256];
 103     int64_t start, end;
 104     AVRational tb = {1, 1e9};
 105     int ret;
 106
 107     get_line(s->pb, line, sizeof(line));
 108
 109     if (sscanf(line, "TIMEBASE=%d/%d", &tb.num, &tb.den))
 110         get_line(s->pb, line, sizeof(line));
 111     ret = sscanf(line, "START=%"SCNd64, &start);
 112     if (ret <= 0) {
 113         av_log(s, AV_LOG_ERROR, "Expected chapter start timestamp, found %s.\n", line);
 114         start = (s->nb_chapters && s->chapters[s->nb_chapters - 1]->end != AV_NOPTS_VALUE) ?
 115                  s->chapters[s->nb_chapters - 1]->end : 0;
 116     } else
 117         get_line(s->pb, line, sizeof(line));
 118
 119     ret = sscanf(line, "END=%"SCNd64, &end);
 120     if (ret <= 0) {
 121         av_log(s, AV_LOG_ERROR, "Expected chapter end timestamp, found %s.\n", line);
 122         end = AV_NOPTS_VALUE;
 123     }
 124
 125     return avpriv_new_chapter(s, s->nb_chapters, tb, start, end, NULL);
 126 }
 127
 128 static uint8_t *unescape(const uint8_t *buf, int size)
 129 {
 130     uint8_t *ret = av_malloc(size + 1);
 131     uint8_t *p1  = ret;
 132     const uint8_t *p2 = buf;
 133
 134     if (!ret)
 135         return NULL;
 136
 137     while (p2 < buf + size) {
 138         if (*p2 == '\\')
 139             p2++;
 140         *p1++ = *p2++;
 141     }
 142     *p1 = 0;
 143     return ret;
 144 }
 145
 146 static int read_tag(const uint8_t *line, AVDictionary **m)
 147 {
 148     uint8_t *key, *value;
 149     const uint8_t *p = line;
 150
 151     /* find first not escaped '=' */
 152     while (1) {
 153         if (*p == '=')
 154             break;
 155         else if (*p == '\\')
 156             p++;
 157
 158         if (*p++)
 159             continue;
 160
 161         return 0;
 162     }
 163
 164     if (!(key = unescape(line, p - line)))
 165         return AVERROR(ENOMEM);
 166     if (!(value = unescape(p + 1, strlen(p + 1)))) {
 167         av_free(key);
 168         return AVERROR(ENOMEM);
 169     }
 170
 171     av_dict_set(m, key, value, AV_DICT_DONT_STRDUP_KEY | AV_DICT_DONT_STRDUP_VAL);
 172     return 0;
 173 }
 174
 175 static int read_header(AVFormatContext *s)
 176 {
 177     AVDictionary **m = &s->metadata;
 178     AVBPrint bp;
 179
 180     av_bprint_init(&bp, 0, AV_BPRINT_SIZE_UNLIMITED);
 181
 182     while(!avio_feof(s->pb)) {
 183         get_bprint_line(s->pb, &bp);
 184
 185         if (bp.len == strlen(ID_STREAM) && !memcmp(bp.str, ID_STREAM, strlen(ID_STREAM))) {
 186             AVStream *st = avformat_new_stream(s, NULL);
 187
 188             if (!st)
 189                 goto nomem;
 190
 191             st->codecpar->codec_type = AVMEDIA_TYPE_DATA;
 192             st->codecpar->codec_id   = AV_CODEC_ID_FFMETADATA;
 193
 194             m = &st->metadata;
 195         } else if (bp.len == strlen(ID_CHAPTER) && !memcmp(bp.str, ID_CHAPTER, strlen(ID_CHAPTER))) {
 196             AVChapter *ch = read_chapter(s);
 197
 198             if (!ch)
 199                 goto nomem;
 200
 201             m = &ch->metadata;
 202         } else
 203             read_tag(bp.str, m);
 204     }
 205
 206     av_bprint_finalize(&bp, NULL);
 207
 208     s->start_time = 0;
 209     if (s->nb_chapters)
 210         s->duration = av_rescale_q(s->chapters[s->nb_chapters - 1]->end,
 211                                    s->chapters[s->nb_chapters - 1]->time_base,
 212                                    AV_TIME_BASE_Q);
 213
 214     return 0;
 215 nomem:
 216     av_bprint_finalize(&bp, NULL);
 217
 218     return AVERROR(ENOMEM);
 219 }
 220
 221 static int read_packet(AVFormatContext *s, AVPacket *pkt)
 222 {
 223     return AVERROR_EOF;
 224 }
 225
 226 const FFInputFormat ff_ffmetadata_demuxer = {
 227     .p.name      = "ffmetadata",
 228     .p.long_name = NULL_IF_CONFIG_SMALL("FFmpeg metadata in text"),
 229     .read_probe  = probe,
 230     .read_header = read_header,
 231     .read_packet = read_packet,
 232 };