[Pkg-kde-extras] Bug#680916: kid3: Performer tag silently replaced with an Arranger one

[Urs Fleisch]

Kid3 supports lots of different tag formats. All these formats have different fields, not all fields are present in all formats. Kid3 tries to unify the common field types between all supported formats, the unified fields are the "standard" fields from Title to Genre and additional fields from Album Artist to Website. Besides these unified fields, a lot of other format specific fields are supported, for ID3v2.3.0 from AENC to WXXX.

Now there is the problem that not all of the unified fields can be unambiguously mapped to the fields of all formats. Here we have the Performer and Arranger fields. For ID3v2.4.0, Arranger is mapped to "TIPL Involved people list" and Performer is mapped to "TMCL Musician credits list".

  TMCL
   The 'Musician credits list' is intended as a mapping between
   instruments and the musician that played it. Every odd field is an
   instrument and every even is an artist or a comma delimited list of
   artists.

  TIPL
   The 'Involved people list' is very similar to the musician credits
   list, but maps between functions, like producer, and names.

However, in ID3v2.3.0, there is no such thing as TMCL, only IPLS (Involved people list), so both musicians and other involved people like the producer have to use the IPLS field. That's why Kid3 maps both Performer and Arranger to IPLS, and when the file is read back, there are two IPLS frames which are displayed as Arranger.

So this is not a bug in Kid3, only a thing where ID3v2.3.0 is not as expressive as ID3v2.4.0. You can use ID3v2.4.0 if this is really a problem.