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Does format guiding really work for CT raw image?

Posted: Thu Jun 07, 2018 7:46 pm
by softwarefailure
I have experienced some suspicious behaviour when dumping disks using the Java GUI. I select <Multiple> as the output format and then I select all of the following items:

1) Kryoflux stream files, preservation
2) CT raw image
3) AmigaDOS sector image

The suspicious behaviour I noticed is this:

When I tried to dump the game "Doofus", all tracks were green except tracks 80 and 81 which were gray but that is normal I guess. HOWEVER, when I tried to start the CT raw image in WinUAE, WinUAE complained "The selected floppy disk image is damaged or unformatted". The ADF image, however, booted fine but the copy protection kicked in after the logo screen. The interesting thing comes now: I then repeated the dumping process of Doofus a few times and after three more tries or so the CT raw image suddenly booted and I could play the game just fine! How can this possibly be when all tracks were green already when I first dumped the image? To me, the only explanation is that during the first read the ADF was dumped ok but there were some invalid bytes dumped to the CT raw image and that's why WinUAE refused to boot it. But how can this be if all tracks are green? It looks like the ADF and CT raw tracks aren't completely in sync.

The experience I made with Doofus was also very similar to my experience when dumping Lost Patrol:

When dumping Lost Patrol using the settings above, all tracks were green except track 0 side 1 which was gray and probably a track for the copy protection. When I then booted the CT raw image, it showed the intro and then the map screen and after that there was a screen with a disk that said READ ERROR. So I once again dumped Lost Patrol a few more times and suddenly the screen saying READ ERROR was gone and the game worked fine. BUT: According to the Kryoflux Java GUI, all tracks (except track 0 side 1 but this is probably only for copy protection) could be read just fine already on my first dumping attempt. But when I booted the game, it said READ ERROR after the map screen. So where does the read error come from? All tracks were green?!

What I saw was, that while dumping those two games, some tracks were first red and after a few retries they were finally green. So to me it looks like format guiding doesn't really work because the CT raw image was bad even though all tracks were green. It looks like the data from the first read attempt was written to the CT raw image even if the data was bad and only the ADF profited from read retries. Could this be the case? Or does anybody have another idea that could explain the behaviour I'm seeing here?

I'm a little confused I have to admit. I thought that if all tracks were green then the disk would definitely be ok but that doesn't seem to be the case :-(

Re: Does format guiding really work for CT raw image?

Posted: Fri Jun 08, 2018 6:53 pm
by softwarefailure
Addendum: I have set "-t99" for AmigaDOS sector image if that is of any signifance. Could this mean that it only retries 99 times for AmigaDOS sector image and uses the default of 5 retries for CT raw image? That could explain why the CT raw image is sometimes broken even though all tracks were green.

Re: Does format guiding really work for CT raw image?

Posted: Mon Jun 11, 2018 8:33 pm
by mr.vince
There is data beyond AmigaDOS (e.g. "garbage" in the gap) and if it's prepped to work as a protection, which is either violating recording rules (which would trigger an ADOS error) or by placing meaningful data in non-data areas (as outlined: e.g. the gap) then this is possible. There is no way to automatically detect all protections, as they go beyond of standard OS stuff. It might also be possible that the same error happens on real hardware.

Solution: Use a tool that can also analyse protections and e.g. gap data. We use e.g. the Softpres Analyser.

Re: Does format guiding really work for CT raw image?

Posted: Tue Jun 12, 2018 6:54 pm
by softwarefailure
Thanks, where can I get the Softpress Analyzer? Is this freely available?

Re: Does format guiding really work for CT raw image?

Posted: Tue Jun 26, 2018 6:39 am
by mr.vince
This is a separate product aimed at Institutions, Archives etc., and comes with a very different price tag. You can contact us for a quote, but again, it's pro software.