redump.info Forum

So, if 2 peole have the same dump and run it through packiso, they will get bit for bit identical output files no matter what computer/os they use? I'm a member of a well know retro gaming torrent tracker, and the 'masters' over their always pray that the only way for two people to get same checksums it to use torrentzip. Especially a 'torrent7zip' tool were called impossible due to 7zip not beeing able to produce identical files (and a too lousy source code to make it do so).

So far, files compressed with packiso have been identical for different people on different computers. Of course there is the possibility that there is an odd configuration where the result will be different, but this could happen with torrentzip aswell.

Those people should try it instead of praying.

...but this could happen with torrentzip aswell

No, it couldn't
Unless there was an error of course.

But seriously, from what I know of torrentzip, it was designed specifically to make identical results regardless of machine/OS (most probably by using integers only).

I thought the same could be done with 7zip, so when you said that PackISO got identical results on different machines I thought this was the case.

Compression algorithms are usually integer based.
So far same versions of 7zip used with the same options made identical results.
That is at least true for the Windows version of 7zip.

But Winrar for instance gives me different results on different system. Tested with same settings, but once on a  Turion Laptop with 2 Gig RAM and once with an old first gen. Pentium 4 with 512 MB. Torrentzip was specially developed with this aspect in mind, even an old Pentium 1 system should give you same results. I guess  I will do some tests to proof 7zip.

If someday Daemon Tools will support compressed audio, this would be the perfect solution.

Sotho Tal Ker wrote:Those people should try it instead of praying.

It has been discussed several times, but sadly they are not so open minded for new ways....

I compiled p7zip 4.53 on a OpenBSD system (Pentium III 800MHz), used "touch -t 197912310900.00" on the file and compressed it with "7za a file.7z file.ecm"; then I used packiso on a WinXP SP3 system (AMD Sempron 3000+) on the same file.
Though the 7z size was the same on both machines, their md5 was different.

It's a shame that the guys who did torrentzip have no intention of doing a torrent7z...

ssjkakaroto wrote:Though the 7z size was the same on both machines, their md5 was different.

Can you do a binary compare to see how different those 2 files are? Maybe there is only a difference in the file header or the whole data stream is different.

ssjkakaroto wrote:I compiled p7zip 4.53 on a OpenBSD system (Pentium III 800MHz), used "touch -t 197912310900.00" on the file and compressed it with "7za a file.7z file.ecm"; then I used packiso on a WinXP SP3 system (AMD Sempron 3000+) on the same file.
Though the 7z size was the same on both machines, their md5 was different.

It's a shame that the guys who did torrentzip have no intention of doing a torrent7z...

The problem probably is with time stamp and file atributes, as rmdtrasht.exe set the date to 1980/01/01 01:00.00 (i think it's (GMt) Greenwitch Mean Time) and removes all file atributes. Of course date must be set for: created, modified and accessed time stamps.

Sotho Tal Ker: The differences are only on the 2 first and 2 last offsets of the file
Probably touch is missing something that rmdtrash cleans.

Volkov wrote:Can the creater of PackPS2, edit the program to be made to compress things besides ISO?  It just 7z the file right?  Should work for anything?  Hopefully someone can help me

i will add the remaining image format on Monday, i won't be going to office before that and the source code is on my office PC