recode .iso

[pklat]

Greets,
I've created a simple perl script to unpack .iso files, while keeping the 'metadata' in sparsefile (so that .iso can be re-generated later):

https://gitlab.com/pklat/reiso


Thanks.

[Gonzalo]

Welcome to the forum!

This is very similar (at least in concept) to this other tool. It does the same as your script but for cab archives and accounting for the data being compress with the LZX algorithm.There's been some talk about including this extraction-based approach to recompression in the Fairytale project too, in case you're interested.

What would be the use case for reiso? Is it intended as a pre-compression tool? Maybe it's possible for you to include other file formats as well?

[pklat]

Thank you Gonzalo.
I had been thinking along the same lines.
Perhaps this perl script isn't useful, given that precomp works nicely with .iso files as they are.

[moisesmcardona]

Thank you Gonzalo.
I had been thinking along the same lines.
Perhaps this perl script isn't useful, given that precomp works nicely with .iso files as they are.

It's nice to see new tools every time. Thanks for sharing your work with us

[Gonzalo]

Thank you Gonzalo.
I had been thinking along the same lines.
Perhaps this perl script isn't useful, given that precomp works nicely with .iso files as they are.

Oh, on the contrary. It is useful indeed. Personally, I think the field could use a lot more of pre-compressors and re-compressors. Your take is somewhat different to that of precomp. Precomp, and hopefully Fairytale will only take advantage of known, recognizable content in the form of a stream of bytes, not as a file. Using a technique like the one you implemented, non recognized content ('default' category) can at least be sorted by extension, entropy or header / magic bytes.

So keep up with the good work! If I may, the only thing I would recommend is trying not to make yet another standalone tool, but maybe collaborate with a bigger project. Or, do your own thing, but leave the door open so it can be reused (use c/c++, or ship it as a library too)... Just my 2c.

[pklat]

thanks for the kind words, Gonzalo.

I had also been working at rar 'recompressor', long time ago. not by making any programs, but by trying to figure out what were the original rar version and parameters used for a given .rar archive (my 'orar' collection ). I couldn't find an easy way for that. It took some time for each one.

It seems that the problem will be those algorithms for encoding/compressing. Some are under copyright or something, like that rar.
Perhaps Fairytale could have a dir called 'external_compressor' where user would copy all the various .exe files.

as for my little iso recode (idea), I would love if they included it in Fairytale or similar. let me know if I need to change licence or anything.

I just had another idea, given that some files are quite common, on Internet and in general, like basic OS files. Hoping that those won't 'vanish' from Internet and that user can always download them from somewhere, archiver could have an option to simply skip them and store just the metadata?

there are 'whitelist' hash databases of such files, I started one too: https://github.com/orange47/elf_check

[Gonzalo]

You mean something in the lines of this issue? https://github.com/schnaader/fairytale/issues/17

A recompressor for RAR should be possible using a brute-forcing approach. The largest caveat is the licensing thing, but also portability...

[SvenBent]

So this is kinda like a prefiler for .iso files ?

expect some tests comming up this weekend

[pklat]

great. I forgot to mention its totally 'unoptimized'. as it is, it loads the whole .iso into RAM !
there might be problems if .iso contains filenames using some non-usual code page.

[pklat]

sorry to bump.

I've made a lot of changes to https://gitlab.com/pklat/reiso/blob/master/reiso.pm

please try it out. thanks.