[request] Support for CHD on PSP and scan support for CSO and 7z


I’m starting to use RetroArch and I’ve seen that is a very good emulator platform. My principal problem is space, so I want to have the games using the less space posible. I’ve found that PSX games are compatible with Mame CHD (that is very good because use lzma) and I’ve tried to use the same compressión for PSP games to see if I can use it. The tool is able to compress the ISO and reduce it size a lot, but PPSSPP is not able to read that files so my question is: Is possible to add CHD support to PPSSPP?

Another thing I’ve seen is that the program can read CSO and 7z files, but is unable to scan the roms that are in those formats so would be great to have support for scan that roms, because the format uses much less space in some cases.


I will try to answer you as clearly as possible:

  • CHD support to PPSSPP core can happen when happens here: https://github.com/hrydgard/ppsspp So you are asking in the wrong place
  • Scanning 7z files requires first the scanner to be able to extract verify and delete the extracted files then hash the archive and add it to the database as e.g “Game AAA” so that would require possibly a lifetime on slow arm systems like raspberries(raspi). So because most people don’t have a lifetime to spare this is not possible to happen any time soon.


About CHD, thanks, I’ll try to ask for it on core github. I’ve asked here because I didn’t know how the manager works inside (it parse the data to core or the core read the data directly). Now I know that core read the data directly.

About 7zip: Why dont just use the crc stored in 7z container?

Anyway, you can also read the file in chunks to memory directly from 7zip and calculate the CRC without decompress the file (of course, small files, not ISO images). Is much faster than extract the file (much slower write speed), calculate the CRC and delete it…


And who is going to database the correct crc’s for every rom out there in 7zip format? you?

That checksum is the uncompressed file checksum… not the 7zip file checksum. Why do you need a 7zip crc database?.

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That’s also the case for ZIP files. The (uncompressed) CRC-32 of each of the files is stored in each of the File header: https://en.wikipedia.org/wiki/Zip_(file_format)#File_headers (or in some cases, after the compressed data, depending on the compression method). Libraries would normally provide a method to retrieve it (eg. zip_stat from libzip)

Does current Retroarch actually uncompress entire ZIP files when scanning them? I would hope it does not.


@Demetris - Hello, I just became aware that PPSSPP recently added support .chd files. I found this link here.

CHD support added to PPSSPP : emulation (reddit.com)

Do you know if the PPSSPP libertro core will include this feature. I tried mere updating the .nfo file to include the file extension and few conversions of ISO’s I own using both methods described in the link I just shared and no luck… I get a sense that it may not be included in the retroarch core version of PPSSPP but I am not completely sure how the emulators managed by retroarch are updated. Any help would be appreciated. One reason I thought it may already be included is because I had performed the same steps for PS1/PS2 and it worked like a charm. Thank you.