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  1. /*
  2.  * EXIF metadata parser
  3.  * Copyright (c) 2013 Thilo Borgmann <thilo.borgmann _at_ mail.de>
  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. /**
  23.  * @file
  24.  * EXIF metadata parser
  25.  * @author Thilo Borgmann <thilo.borgmann _at_ mail.de>
  26.  */
  27.  
  28. #include "exif.h"
  29.  
  30.  
  31. static const char *exif_get_tag_name(uint16_t id)
  32. {
  33.     int i;
  34.  
  35.     for (i = 0; i < FF_ARRAY_ELEMS(tag_list); i++) {
  36.         if (tag_list[i].id == id)
  37.             return tag_list[i].name;
  38.     }
  39.  
  40.     return NULL;
  41. }
  42.  
  43.  
  44. static int exif_add_metadata(AVCodecContext *avctx, int count, int type,
  45.                              const char *name, const char *sep,
  46.                              GetByteContext *gb, int le,
  47.                              AVDictionary **metadata)
  48. {
  49.     switch(type) {
  50.     case TIFF_DOUBLE   : return ff_tadd_doubles_metadata(count, name, sep, gb, le, metadata);
  51.     case TIFF_SHORT    : return ff_tadd_shorts_metadata(count, name, sep, gb, le, metadata);
  52.     case TIFF_BYTE     :
  53.     case TIFF_UNDEFINED: return ff_tadd_bytes_metadata(count, name, sep, gb, le, metadata);
  54.     case TIFF_STRING   : return ff_tadd_string_metadata(count, name, gb, le, metadata);
  55.     case TIFF_SRATIONAL:
  56.     case TIFF_RATIONAL : return ff_tadd_rational_metadata(count, name, sep, gb, le, metadata);
  57.     case TIFF_SLONG    :
  58.     case TIFF_LONG     : return ff_tadd_long_metadata(count, name, sep, gb, le, metadata);
  59.     default:
  60.         avpriv_request_sample(avctx, "TIFF tag type (%u)", type);
  61.         return 0;
  62.     };
  63. }
  64.  
  65.  
  66. static int exif_decode_tag(AVCodecContext *avctx, GetByteContext *gbytes, int le,
  67.                            int depth, AVDictionary **metadata)
  68. {
  69.     int ret, cur_pos;
  70.     unsigned id, count;
  71.     enum TiffTypes type;
  72.  
  73.     if (depth > 2) {
  74.         return 0;
  75.     }
  76.  
  77.     ff_tread_tag(gbytes, le, &id, &type, &count, &cur_pos);
  78.  
  79.     // read count values and add it metadata
  80.     // store metadata or proceed with next IFD
  81.     ret = ff_tis_ifd(id);
  82.     if (ret) {
  83.         ret = ff_exif_decode_ifd(avctx, gbytes, le, depth + 1, metadata);
  84.     } else {
  85.         const char *name = exif_get_tag_name(id);
  86.         char *use_name   = (char*) name;
  87.  
  88.         if (!use_name) {
  89.             use_name = av_malloc(7);
  90.             if (!use_name) {
  91.                 return AVERROR(ENOMEM);
  92.             }
  93.             snprintf(use_name, 7, "0x%04X", id);
  94.         }
  95.  
  96.         ret = exif_add_metadata(avctx, count, type, use_name, NULL,
  97.                                 gbytes, le, metadata);
  98.  
  99.         if (!name) {
  100.             av_freep(&use_name);
  101.         }
  102.     }
  103.  
  104.     bytestream2_seek(gbytes, cur_pos, SEEK_SET);
  105.  
  106.     return ret;
  107. }
  108.  
  109.  
  110. int ff_exif_decode_ifd(AVCodecContext *avctx, GetByteContext *gbytes, int le,
  111.                        int depth, AVDictionary **metadata)
  112. {
  113.     int i, ret;
  114.     int entries;
  115.  
  116.     entries = ff_tget_short(gbytes, le);
  117.  
  118.     if (bytestream2_get_bytes_left(gbytes) < entries * 12) {
  119.         return AVERROR_INVALIDDATA;
  120.     }
  121.  
  122.     for (i = 0; i < entries; i++) {
  123.         if ((ret = exif_decode_tag(avctx, gbytes, le, depth, metadata)) < 0) {
  124.             return ret;
  125.         }
  126.     }
  127.  
  128.     // return next IDF offset or 0x000000000 or a value < 0 for failure
  129.     return ff_tget_long(gbytes, le);
  130. }
  131.