34     { 
"ALBUMARTIST", 
"album_artist"},
    35     { 
"TRACKNUMBER", 
"track"  },
    36     { 
"DISCNUMBER",  
"disc"   },
    37     { 
"DESCRIPTION", 
"comment" },
    44     len += strlen(vendor_string);
    48             len += 4 +strlen(tag->
key) + 1 + strlen(tag->
value);
    55                            const char *vendor_string)
    57     bytestream_put_le32(p, strlen(vendor_string));
    62         bytestream_put_le32(p, count);
    64             int64_t len1 = strlen(tag->
key);
    65             int64_t len2 = strlen(tag->
value);
    66             if (len1+1+len2 > UINT32_MAX)
    68             bytestream_put_le32(p, len1+1+len2);
    70             bytestream_put_byte(p, 
'=');
    74         bytestream_put_le32(p, 0);
 
int av_dict_count(const AVDictionary *m)
Get number of entries in dictionary. 
AVDictionaryEntry * av_dict_get(const AVDictionary *m, const char *key, const AVDictionaryEntry *prev, int flags)
Get a dictionary entry with matching key. 
static av_always_inline void bytestream_put_buffer(uint8_t **b, const uint8_t *src, unsigned int size)
#define AV_DICT_IGNORE_SUFFIX
Return first entry in a dictionary whose first part corresponds to the search key, ignoring the suffix of the found key string.