id3v2: re-fix handling of v2.4 extended headers
The various id3v2 specs handle the extended header sizes differently
(because hey, it wouldn't be fun otherwise).
http://id3.org/id3v2.3.0 states:
"Where the 'Extended header size', currently 6 or 10 bytes, excludes
itself."
http://id3.org/id3v2.4.0-structure states:
Extended header size 4 * %0xxxxxxx
Number of flag bytes $01
Extended Flags $xx
Where the 'Extended header size' is the size of the whole extended
header, stored as a 32 bit synchsafe integer. An extended header can
thus never have a size of fewer than six bytes.
So in id3v2.4.0 it's the *whole* extended header size (a-la ISOBMFF
atom), whereas in id3v2.3.0 it's the extended header size *excluding*
those 4 initial bytes.
And for other versions, god knows..
Fixes regression introduced in commit da607005.
https://bugzilla.gnome.org/show_bug.cgi?id=792983
1 file changed
