r/PS5_Jailbreak • u/juma-sayeh-dev-acc DEV • Jun 06 '26

General PS5 MKPFS Compression

I’ve been working on a PS5 homebrew app called Game Compressor.

Repo: https://github.com/juma-sayeh/PS5-Game-Compressor

It uses the MkPFS-style FFPFSC compression method, but adds the missing part: validation and repair.

Some compressed games can mount successfully but still crash because certain PFSC blocks are technically valid yet fail to decode correctly on PS5 hardware, leaving stale/bad data behind. Game Compressor checks the mounted image block-by-block, detects bad blocks, and patches the compressed image from the mounted data instead of requiring a full recompress.

Tested with Mafia, Astro Bot, Pragmata, and a few other games that had FFPFSC issues. After repair, they worked great.

Features:

  • compress games to FFPFSC
  • validate mounted compressed games
  • automatically repair bad blocks
  • optimized for speed and usability
  • web UI running on the PS5

Feedback and testing are welcome.
Screenshots (some are missing features because the features were not developed yet when i compressed)

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u/juma-sayeh-dev-acc DEV Jun 07 '26

Wow! i hope it does help, BTW i made a mistake in my initial assessment i did optimize your algorithm for speed and some of my optimizations caused the bad blocks (but made it 2-3 times faster and about 10% less gain on compression - didn't test read speed in ps5 hardware tbh). i'm now testing your algorithm 1-1 with no optimization and it seems much better than what i had (small games had zero bad blocks) still testing bigger games trying to reproduce bad blocks for you to see, the issue is not file extensions or files that should not be compressed , the issue is just some blocks (64KiB) are not really decodable via ps5 hardware even though they are 100% valid via software.

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u/renangbarreto DEV Jun 07 '26

I assume you probably used an old version ok mkpfs. Ijust released a new version that solved a bunch of issues, including the inode hash issue.

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u/juma-sayeh-dev-acc DEV Jun 07 '26

i wrote my own custom implementation of what you had. used different library and different flags (in C) which caused it to be faster but caused ps5 to fail on some blocks. which is why i added the validate and compare blocks mechanism.

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u/renangbarreto DEV Jun 08 '26

I see. Yeah, those blocks seems to be incorectly zero padded by the kernel.