fix or skip dms-errors

[Adderly]

i got again errors while depacking some *.dms files, archives are defect.
I tried to depack them with DMS WBench V2.04 without luck.
Does anyone know how to repair a broken dms-archive or at least how to skip the track with the error on it

You can set the high/low track number if you want to write a dms-file back to disk and DMS will skip the not selected tracks but halts if an error occurs. For example i just need track 70-79 of a corrupt file but because of an error on track 24 it stops depacking/skipping on track 24 with an error message even if i selected only tracks 70-79.

[andreas]

I experienced the same many times.

I think I can give you a 99% non-chance to ever get them repaired, BECAUSE:
A demo group too (name escapes me) suffered from the BBS's obsessions to squeeze every bit out of the files to have them as small as possible.
You might have heard about those algorithms, HEAVY1, HEAVY2 etc.

Now the following happened: the demo group knew that they had to use HEAVY1 for their production, as HEAVY2 caused corruption.
Yet the file was corrupted after downloading from BBS!

Why?

Well, the BBS had done an on-the-fly recompression (presumably on upload), defaulting to HEAVY2, thus *packing* the demo with HEAVY2, corrupting the DMS!!!!
What did they have to do? You might guess it ... release a second version of the affiliated first disk which did work with HEAVY2! No wonder either that on amigascne.org this corrupted version is available only, and I had to look for the second version for awhile!

So why did I write this lot here then? To explain the fact why some DMSes are corrupted for good. They aren't necessarily victim of the BBS's "maximum compression wars", but they might be as well.

[Adderly]

Well, since the sourcecode of xdms and other dms depacker is available in C language i have done some coding.
My version of undms now just depacks a corrupt dms-file and ignores the dms error!
This means all tracks are depacked, also the corrupt track and the ones that follow! Of course, on the corrupt track one or more bytes are not original.

Edit: Anyone with defect dms-files that are worth the time can post here or send a PM, maybe i can fix some of them too.
Sometimes it's enough to extract rare trainer/cracks from the blocks beyond the corrupted track of a dms-file. Then you can apply them on another adf image to get a 100% version. Hey, i already fixed some rare games with this method today!