Hashes aren't well handled.

Both IGameInfo and IMovie have a field called Hash without a defined type.

They are not necessarily the same type: IGameInfo's value can be a CRC32 checksum, an MD5 hash, or a SHA-1 hash depending on which one matches a game in the database, while IMovie's header value is labeled "SHA1".

Going to a more practical issue, there are hash problems when importing fm2, fcm, and mmv movie types. These imported movies will not initialize the movie's Hash field, but instead stuff their data into the otherwise unused MD5 header value. Every time such a movie is opened, the hash comparison fails because the movie file has no hash. However, even if it did setup the hash, there's no guarantee the hash would be the same type because of the earlier-mentioned issues.

This leads to the erroneous message "the movie hash doesn't match the ROM hash" just because the hash was not properly initialized, unrelated to the actual correspondence between the movie and the ROM.

#2328 reminded me of this issue.