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Author Topic: PPF vs. Xdelta  (Read 4025 times)

Burnt Lasagna

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PPF vs. Xdelta
« on: September 21, 2012, 08:53:32 am »
Alright, so pardon if this is somewhat of a dumb question but what exactly is the difference between PPF and Xdelta? I know Xdelta is a more capable format but can it be considered a fault for some cases? I'm wondering this because I generally see people using a mixture of both, which makes me wonder if Xdelta isn't a %100 fool proof patching format that should replace PPF?

I'm asking this because I'm getting ready to release my English dub patch for Ys IV: The Dawn of Ys. I'm gravitating towards Xdelta as the patch format because it doesn't take forever to patch when it's in such a large file. However I'm starting to doubt this decision because I've noticed that this is usually only used with more modern systems, such as PSX, PS2, ect. wile stuff like SNES and Turbografx-CD get left in the cold.

Can someone help clear this up for me?   

Zoinkity

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Re: PPF vs. Xdelta
« Reply #1 on: September 21, 2012, 11:10:51 am »
Xdelta is named after delta (as in 'change') patching, which is handling inserted or deleted information--effectively, cases where the original data in a file is not altered but is offset in some way.

As an example, say you wanted to make a patch to replace the '--' in the first sentence above.  XDelta would only store the removal of the '--' and whatever replaced it.  Other patchers would have to copy the additional 94 characters that follow it.

So, from that perspective, it matters what alterations you've made to the file.  If you've shifted data more than changed it in-place, xdelta would probably be preferable.

In addition, although xdeltas initially appear smaller than other patches, we have to factor in that the data is z compressed.  Minor, in-place changes could actually be better expressed in a gzipped ips of all things. 

PPF stands for 'Playstation patch file' and was originally designed to circumvent the filesize limitation of IPS.  The N64 had its own APS(?) extension which has pretty much died away.  That's the biggest reason you see so many of those on modern systems.  Over time I suspect they'll gravitate more towards xdelta or similiar formats.

There's also the BPS format which is in development.  It's about as small as xdelta and also supports delta mode but significantly less complicated.  It makes up for that by being slower to produce, and at this point isn't well known.

Burnt Lasagna

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Re: PPF vs. Xdelta
« Reply #2 on: September 21, 2012, 04:36:53 pm »
Thank you Zoinkity for the informative response!
So, from that perspective, it matters what alterations you've made to the file.  If you've shifted data more than changed it in-place, xdelta would probably be preferable.
My alterations have all been in place. Basically dumping a string of ADPCM clips to WAV, then syncing the new WAV's with the English audio at the exact length and size of the original before re-inserting.

What I would like to know is that since they've all been in place changes would this create problems if in Xdelta format, or I'm I worrying about nothing?

Zoinkity

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Re: PPF vs. Xdelta
« Reply #3 on: September 22, 2012, 08:35:24 am »
It works either way.  You might be able to get a slightly smaller filesize out of compressing another patching format, but xdelta can handle either situation. 

Burnt Lasagna

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Re: PPF vs. Xdelta
« Reply #4 on: September 22, 2012, 11:27:27 am »
Thanks for the confirmation!
I figured that was the case, but it's always good to get a second opinion.