MakeMKV uses ISO-639-2/T instead of ISO-639-2/B (lang codes)

[Romansh]

Create an MKV file from a Blu-Ray with MakeMKV, include a French subtitle track. Open the MKV in MediaInfo - the subtitle track is correctly labeled as French.

Now load the same MKV file in mkvmerge GUI, highlight the subtitle track (do not highlight any other track first): the language displayed is "Undetermined".
This likely indicates that MakeMKV uses the ISO-639-2/T code ("fra"), which mkvmerge GUI doesn't support:

https://www.bunkus.org/bugzilla/show_bug.cgi?id=598

The mkvmerge developer claims the MKV spec mandates ISO-639-2/B (in this case, "fre").
ISO-639-2/T codes appear generally well supported by players (e.g. VLC, MPlayer - and WDTV Live, IIRC) and similar software (MediaInfo), but it seems the /B variant is at least the preferred form:

http://matroska.org/technical/specs/ind ... #languages

The players I mentioned and MediaInfo seem to support the /B variant as well.

[mike admin]

MakeMKV puts iso-639-3 codes.

[Romansh]

MakeMKV puts iso-639-3 codes.

Heh.