This section attempts to describe some intricacies regarding character sets and encodings in tags.
Text in ID3v2 tags can be encoded in a variety of ways. ID3v2.3 and earlier standards support only text encoded in ISO 8859-1 and UCS-2. ID3v2.4 added support for UTF-8 and UTF-16BE1, and replaced UCS-2 with UTF-16.
If you are using id3lib, only ISO 8859-1 and UCS-2/UTF-16 encodings of ID3v2.4 tags are supported. The current C API of id3lib must be extended in order to support UTF-8 and UTF-16BE for ID3v2.4. (Especially, a function ID3Field_GetEncoding is missing.)
TagLib seems to support all encodings used in ID3v2.4 tags.
Unfortunately, many applications still put UTF-8 encoded text in ID3v2.3 and earlier tags. This is incorrect according to the standard2 - single-byte text should be encoded in ISO 8859-1 and nothing else. TagLib handles all single-byte text in ID3v1 and ID3v2.3 tags as ISO 8859-1, while id3lib gives you the option to treat the data as you like. At the moment, GMediaServer assumes single-byte text is encoded in ISO 8859-1 when using id3lib.