I added both a custom column and input in the tag panel for a field %MEDIATYPE%, which keeps getting written out to a tag named "MEDIA TYPE". As a result the information is not picked up in applications expecting the name to be "MEDIATYPE"
EDIT: FYI, this is in 2.75
EDIT2: if I use another program to add/populate the tag , it does get written out as MEDIATAG, and what's worse, MP3tag then reads that tag.... but when information gets updated, deletes the old name and writes it out as "MEDIA TYPE" again. Which is not cool!
See Mp3tag help manual "Tag field mappings".
The ID3 tagfield TMED, which is defined for the tagtypes ID3v2.3 and ID3v2.4, has the name MEDIATYPE in Mp3tag.
If you want to write data into this tagfield then use the name MEDIATYPE.
If you want to read data from this tagfield then use the name of the tagfield enclosed into "content operators", written as %MEDIATYPE%.
If you want to set the title of a user dialog input box in the "Tag-Panel" window, then you are allowed to use a name of your wish, for example "Media T&ype", which additionally defines the Hotkey [Alt+Y].
Other applications might show different tagfield names, ...
for example ... FB2K foobar2000 displays the Metadata name .
This is exactly what I am doing... and I don't care what other applications do. I have defined a field MEDIATYPE (without! the SPACE. but MP3Tag insists on writing it out WITH a space. even though it is defined WITHOUT a space...
And this leads to other applications using the tag as MEDIATYPE (again WITHOUT space) to not pickup the change. since instead of MEDIATYPE (WITHOUT a space) it turns up as MEDIA TYPE (WITH a space)
EDIT: I've attached some screenshots to show what is happening.
You will see it is defined without a space but ends up with a space... and potentially this could lead to even worse situations as shown in the 4th screenshot where both tags are together if MP3Tag didn't first delete the old name and created the new one. At least that makes it glaringly visual by the absence of the value if viewed outside of MP3tag.
EDIT2: further proof that MP3tag inserts the space, after adding the expected tag too as it is known in my other programs, as shown in the 4th screenshot, and reading the media file back in MP3tag, guess which of the two values it read...
Exactly, the one WITH the space.
Since the ID3v2.3 description itself refers to the TMED frame as MEDIA TYPE (using separate words) and as shown in the screenshot. both the custom TXXX frame and the original TMED can co-exist perfectly well together, the choice was made to use MEDIATYPE as name for the custom column, which gets treated as a custom TXXX frame.
The reason for creating the custom field I would think was obvious, so as not to destroy the value that might exist in the official TMED frame. Also because it serves a different purpose.
the TMED frame describes the source of the media file while the TXXX version is intended to describe the actual format of the media file itself and not the source it came from.
Mp3Tag has the Tagname "Mediatype" for the TMED frame.
So when you create a column or a field in the Tag-Panel and use the field %mediatype% you get the TMED frame and the field is not renamed.
What obviously confuses you is that Foobar shows this tag as "Media Type", not because Mp3Tag has named it like that but only because Foobar shows the TMED-frame this way.
If you create a second mediatype tag-field in MP3Tag you get a multivalue field named "Mediatype". If you open the extended tag-view you can see 2 fieldds named Mediatype. Mp3Tag does not rename anything. It justs creates a TMED-field.