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[Svenny]

Hi Roman,
I've read that you consider it to be "dirty" to store CHD subfolders as packed ZIP files in your ROMS rootfolder. Nevertheless it still works in MAME and saves some disk space.
Therefore I have set the option "allow CHDs in ROMpath root" to yes inside the advanced scanner options. But still my zipped subfolders are reported as unneeded files and Clrmame suggests to delete them. What can I do?
Thanks for your assistance!
Svenny

[Roman]

There are 2 ways to store chds.

Either the good old way:

rompath\setname\chdfilename1 ... chd filename n

or the "we really don't like it" way in a rompath root:

rompath\chdfilename 1... chdfilename n

For this second option you have to enable Scanner->Advanced->"Allow CHDs in rompath root" option.



....since these are the 2 modes, anything else is not supported. Especially not zipping up chds. Where is the sense anyway. CHDs are zlib compressed already. Waste of decompression time and memory usage.

[Svenny]

Why?

1) Zipped chds are (in average) 10% smaller. That's a lot of diskspace.
2) Mame supports it fine.

Thanks anyway.

[Roman]

Nonsense

a) diskspace doesn't matter. In times of terabyte hds and laserdisk chds you talk about a minimum saving
b) chds ARE zip compressed already. CHD is a container for raw data which is sector wise zlib compressed
c) it's a memory hog if you keep chds compressed. You won't be able to run them fine in MAME (except the small ones). Great idea to zip a 15GB file which needs to get decompressed into memory when loading the game and then needs random access on it.


To sum it up: zipping chds is nonsense.

[Svenny]

I would sum it up this way: Mame supports it, but Clrmame doesn't. Thank you anyway my friend.

 

[Roman]

You're wrong. Mame does not support it correctly. Try to zip up mach3.chd and try to load it in MAME....have fun. (Besides that standard zip only supports files < 4GB).

Besides of this, what MAME does and what it does not doesn't play a role. MAME loads files in a very lazy way, it simply loads by hash, no matter if the files are in the correct set of a parent/clone relationship. It simply scans everything related for a match.
MAME's loading mechanism is one thing, auditing is something else.