PPF vs IPS
PPF and IPS are not really competitors. PPF was designed for CD and DVD disc images, where files are hundreds of megabytes and size must never change. IPS was designed for cartridge ROMs and cannot address past 16 MB. Pick based on what you are patching.
PPF for disc images, IPS for cartridge ROMs.
| PPF | IPS | |
|---|---|---|
| Designed for | CD and DVD disc images | Cartridge ROMs |
| Maximum target size | No practical limit | 16 MB |
| Can change file size | No | Can grow only |
| Verifies your file | v2 and v3 partially, v1 not at all | No |
| Typical systems | PlayStation, PS2, Saturn, Dreamcast | NES, SNES, Game Boy, Genesis |
Two formats for two different jobs
PPF writes changes at absolute offsets into a large image and deliberately never alters its size, which keeps the disc structure and any accompanying .cue file valid. IPS does something similar in spirit but with 24-bit offsets, capping it at 16 MB and ruling out disc images entirely.
You will essentially never have to choose between them, because the file you are patching decides for you.
Frequently asked questions
Can I use an IPS patch on a PlayStation ISO?
Practically never. IPS offsets cap out at 16 MB, so the format cannot describe a change anywhere past that point in a disc image. PPF or xdelta is what those projects use.
Does PPF verify my disc image?
Only partially, and only in later versions. PPF 2.0 compares a 1024-byte block of the image, PPF 3.0 makes that optional, and PPF 1.0 checks nothing at all.