MAMEWorld Forums - EmuChat - Re: Chdman questions

> Given that the individual files are listed, I don't get why the file size and sha1
> can't be as well

I'm not sure if I understand what you mean by this. A .chd has a file, not files. The metadata describes what went into that file, but not the way DOS does, the descriptions are not based on conventional filenames, filesizes and individual hashes.

The .chd format was not designed to be another archive format like .rar or .7z. Conventional archive formats are designed from the ground up to be general purpose.

At first, the .chd format was designed to be very specific to compressing the data found the hard disks on arcade games. It needed to be fast, it has to unpack the data much more quickly than conventional archive systems, because there's a game going on in the background. One doesn't have the luxury to stop the game to unpack a large or tightly-compressed file. There was no need to catalog the files on the compressed hard disk, the decompression system unpacked the raw sectors as needed. The only info needed was the cylinder and sector layout to describe the physical properties of the uncompressed media.

Later, when it came time to emulate arcade games that used CDROM (and later, flash) as the media, the .chd format was expanded to cover the those. (This is the metadata information) The emphasis continues to be to support the raw data, not caring what the game calls it's files and folders internally.

This is why your inquiries are not making sense to the MAMEdevs. They don't have any interest in developing another archive format. The .chd format as it stands works fine for it's intended purpose.

Although you can see great benefit if there was an easier way to translate the .chd format to a conventional view of files and folders, there is no point in doing that because it does not contribute to the emulation process.

I'm not trying to tell you to stop trying to convince them, perhaps you can think of another tack to make it a benefit to have more extended information as part of the .chd format, instead of a hindrance.