id3v2enc.c
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1 /*
2  * ID3v2 header writer
3  *
4  * This file is part of Libav.
5  *
6  * Libav 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  * Libav 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 Libav; if not, write to the Free Software
18  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
19  */
20 
21 #include <stdint.h>
22 
23 #include "libavutil/dict.h"
24 #include "libavutil/intreadwrite.h"
25 #include "avformat.h"
26 #include "avio.h"
27 #include "id3v2.h"
28 
29 static void id3v2_put_size(AVFormatContext *s, int size)
30 {
31  avio_w8(s->pb, size >> 21 & 0x7f);
32  avio_w8(s->pb, size >> 14 & 0x7f);
33  avio_w8(s->pb, size >> 7 & 0x7f);
34  avio_w8(s->pb, size & 0x7f);
35 }
36 
37 static int string_is_ascii(const uint8_t *str)
38 {
39  while (*str && *str < 128) str++;
40  return !*str;
41 }
42 
48 static int id3v2_put_ttag(AVFormatContext *s, const char *str1, const char *str2,
49  uint32_t tag, enum ID3v2Encoding enc)
50 {
51  int len;
52  uint8_t *pb;
53  int (*put)(AVIOContext*, const char*);
54  AVIOContext *dyn_buf;
55  if (avio_open_dyn_buf(&dyn_buf) < 0)
56  return AVERROR(ENOMEM);
57 
58  /* check if the strings are ASCII-only and use UTF16 only if
59  * they're not */
60  if (enc == ID3v2_ENCODING_UTF16BOM && string_is_ascii(str1) &&
61  (!str2 || string_is_ascii(str2)))
63 
64  avio_w8(dyn_buf, enc);
65  if (enc == ID3v2_ENCODING_UTF16BOM) {
66  avio_wl16(dyn_buf, 0xFEFF); /* BOM */
68  } else
69  put = avio_put_str;
70 
71  put(dyn_buf, str1);
72  if (str2)
73  put(dyn_buf, str2);
74  len = avio_close_dyn_buf(dyn_buf, &pb);
75 
76  avio_wb32(s->pb, tag);
77  id3v2_put_size(s, len);
78  avio_wb16(s->pb, 0);
79  avio_write(s->pb, pb, len);
80 
81  av_freep(&pb);
82  return len + ID3v2_HEADER_SIZE;
83 }
84 
85 static int id3v2_check_write_tag(AVFormatContext *s, AVDictionaryEntry *t, const char table[][4],
86  enum ID3v2Encoding enc)
87 {
88  uint32_t tag;
89  int i;
90 
91  if (t->key[0] != 'T' || strlen(t->key) != 4)
92  return -1;
93  tag = AV_RB32(t->key);
94  for (i = 0; *table[i]; i++)
95  if (tag == AV_RB32(table[i]))
96  return id3v2_put_ttag(s, t->value, NULL, tag, enc);
97  return -1;
98 }
99 
100 int ff_id3v2_write(struct AVFormatContext *s, int id3v2_version,
101  const char *magic)
102 {
103  int64_t size_pos, cur_pos;
105 
106  int totlen = 0, enc = id3v2_version == 3 ? ID3v2_ENCODING_UTF16BOM :
108 
109 
110  avio_wb32(s->pb, MKBETAG(magic[0], magic[1], magic[2], id3v2_version));
111  avio_w8(s->pb, 0);
112  avio_w8(s->pb, 0); /* flags */
113 
114  /* reserve space for size */
115  size_pos = avio_tell(s->pb);
116  avio_wb32(s->pb, 0);
117 
119  if (id3v2_version == 4)
121 
122  while ((t = av_dict_get(s->metadata, "", t, AV_DICT_IGNORE_SUFFIX))) {
123  int ret;
124 
125  if ((ret = id3v2_check_write_tag(s, t, ff_id3v2_tags, enc)) > 0) {
126  totlen += ret;
127  continue;
128  }
129  if ((ret = id3v2_check_write_tag(s, t, id3v2_version == 3 ?
130  ff_id3v2_3_tags : ff_id3v2_4_tags, enc)) > 0) {
131  totlen += ret;
132  continue;
133  }
134 
135  /* unknown tag, write as TXXX frame */
136  if ((ret = id3v2_put_ttag(s, t->key, t->value, MKBETAG('T', 'X', 'X', 'X'), enc)) < 0)
137  return ret;
138  totlen += ret;
139  }
140 
141  cur_pos = avio_tell(s->pb);
142  avio_seek(s->pb, size_pos, SEEK_SET);
143  id3v2_put_size(s, totlen);
144  avio_seek(s->pb, cur_pos, SEEK_SET);
145  return 0;
146 }