Do we know what should happen if MT_AM_FORMAT_TYPE is used with non-zero GUID value?
My understanding is that the content of `MT_USER_DATA` is either: - `WAVEFORMATEX` / `WAVEFORMATEXTENSIBLE` (for raw audio); or - arbitrary binary data where the expected format of that data is defined by `MT_AM_FORMAT_TYPE` (`GUID_NULL` meaning we can ignore it) https://learn.microsoft.com/en-us/windows/win32/medfound/mf-mt-am-format-typ... https://learn.microsoft.com/en-us/windows/win32/medfound/mf-mt-user-data-att...
This nesting check looks too complicated and something to be changed completely once we need to handle non-zero guids.
Agreed. I'll to look rewrite that and push a change. -- https://gitlab.winehq.org/wine/wine/-/merge_requests/7417#note_95938