Yes, I can look for and ask people I know about such files to test on them if it would help in any way. You can email me at my nickname tuta dot io, or on telegram at the same nickname, it will be easier and faster.
Yes, sorry, I completely forgot to add, here for example: https://soundcloud.com/professorkliq/chasing-time-pk-remix Button "More" => "Download file" How to reproduce, compress: "flac.134 --keep-foreign-metadata --no-padding --best --verify" Now unpack with different versions: "flac.132 -d --keep-foreign-metadata" "flac.134 -d --keep-foreign-metadata" Unpacked 134: will be with a different header.
I don't know what kind of chunk it is, the author creates a file on the "OP-1 sketch sequencer" device, so this is probably some kind of padding hardwired by the manufacturer according to some kind of standard or for his own purposes. In general, I just thought that such extra-data with the "keep-foreign-metadata" key can be stored compressed, anyway, when playing, they are never used and are not displayed anywhere, i.e. needed only to return the original file. In addition, the "option" to archive...
flac does not properly handle "keep-foreign-metadata" with format "aiff" and codec "sowt"
Flac versions 1.33/34 ignore the "--keep-foreign-metadata" option when unpacking