[X] Can't copy some unusual TRACK tags from MP3 / FLAC to WMA

[ryerman]

@zerow

So the bug is: it can be copied, but to MP3 and FLAC; but such an attempt on a WMA file will spit out an error saying, that it cannot be opened for writing

This is not a bug, but the result of an Mp3tag feature.

WMA files use ASF (Advanced Systems Format) tags.
see here:
https://msdn.microsoft.com/en-us/library/wi...v=vs.85%29.aspx
https://msdn.microsoft.com/en-us/library/wi...v=vs.85%29.aspx

My understanding is this:

ASF tags support both Track and TrackNumber.
Track is 0-based and included for legacy reasons. (ie back-wards support)
TrackNumber is 1-based.
Mp3tag writes both.

You may ask, "How does Mp3tag write those tags?"

Only the developer knows for sure, but my observations suggest this:
Whatever number is entered by the user becomes TrackNumber.
Track is calculated by substracting 1 from the integer portion (the part before the decimal) of TrackNumber.

This means that you may only enter any decimal number greater than greater than or equal to 1. [EDIT]
Anything else will cause the warning you have seen.
This allows the feature of writing both Track and TrackNumber.

For example:
If you enter 1, then TrackNumber = 1 and Track = 0
If you enter 1.12345, then TrackNumber = 1.12345 and Track = 0
If you enter 1.9, then TrackNumber = 1.9 and Track = 0
If you enter +1.9, then TrackNumber = +1.9 and Track = 0
If you enter +300.9, then TrackNumber = +300.9 and Track = 299