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Grabbed a disc with no errors, ISO came up short

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I tried to first search the forum for this issue but didn't find anything so I'm opening up a bug topic.

 

With CDBurnerXP 4.5.8.6795 on Win10 64 bit I was using the copy/grab a disc option to capture a CD to an ISO.  CDXP did so without errors and I transferred it to the system where it was needed.  That system would error when attempting to mount the ISO image.  I tried capture with a different optical drive as well as a fresh transfer to the target system, still no go.

I then tried capture with two different apps.  The first was on the same computer and with the same optical drives used earlier, the second was on a completely different system with a different OS to boot.  All of these new ISO captures were usable.  I did a binary compare of all the ISOs I created.  Those made with CDXP matched each other and those made with the other programs matched each other.  But if I cross compared the response was that the data matched, but the file lengths did not.  The CDXP ISOs were 4KB smaller than the other ISOs. (In this test, 567,107,584 bytes compared to 567,111,680 bytes respectively.)

I brought the files into a hex editor and inspected them.  Each of the ISOs ended with non-0x00 data at the same place and then followed with a with a long series 0x00 bytes to the end of file.  But the non-CDXP ISOs had an additional 4KB of these empty bytes.

This was a monthly product update CD where I've ripped past updates with CDXP without issue, along with other monthly updates from the same publisher that come on DVDs and have had no issues there.  I've got no idea what is different about this disc that has caused CDXP to short the ISO image by 4KB but the other applications captured the ISO successfully.  Any ideas?

 

In all the years I've been CDBurnerXP this is the first issue I've ever encountered.  It is my go-to and recommended software for capturing/burning in Windows.  I hope the information I've provided can help to quickly get to the bottom of this bug!

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The system where we then attempted to load the ISO image for a product upgrade failed to do so; it detected something invalid about it and wouldn't allow it to be mounted. The image that I later ripped with different software mounted fine. We get these optical disc updates from the vendor once a month for three different products. For a number of months now I've been using CDBurnerXP to create the ISO images we then FTP to the target systems and haven't had any prior issue. It seems there is something about one of the discs this month that CDBurnerXP didn't handle correctly, yet other software ripped us a working image. And all the images match byte-for-byte except that the CDBurnerXP image is missing the last 4K, which happens to be 0x00 repeated over and over.

The CD is an ISO9660 filesystem with single data track. Some searching tells me that the ISO9660 primary volume descriptor contains a value for the number of logical blocks used by the disc. I would then find it possible that if the software attempting to mount the image did a sanity check to confirm the image was the length described in the volume descriptor, that being short 4K would cause it to error out. But this is just taking a guess based on what seems logical to me courtesy of internet research... I haven't figured out how to break apart the values of the volume descriptor and see if any math checks out.

Side note, it has been interesting to peek into the detail of this format...

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Might also be some kind of copy protection. StaBurn might need to have a look at that, but they got their hands full with a different issue currently so I can't investigate that further at the moment.

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OK. I'm doubtful the vendor would be using any copy protection since I believe these are one-off burns with content keyed to our system serial number, but who knows. We'll see what happens with future updates from them. If another one pops up with a problem I'll investigate as I did this one and report my findings. Thanks!

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I checked with the vendor, they stated there was nothing sensitive on the media or anything in our license that would prevent us from sharing the original physical disc with you. It will be another month until we hit our rotation where the disc would be considered obsolete and be destroyed but instead for this one I could mail it out to a developer if you guys would want to investigate further. Just did our latest updates from the vendor and the most recent discs had no problem. Looks like it is just something with this one disc that threw off CDBurnerXP when ripping the ISO.

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Just got this month's update disc, issue has returned. Last 4096 bytes missing in the CDBurnerXP rip when compared to the size of the source CD but came up a match when taken via another ripper. Pattern of bytes at the end of the ISOs are the same. When examined in a hex editor the "data" appears to end at 0x222F8FF0, is then filled with 0x00 until 0x22342FF0 on the CDBurnerXP rip but continues another 4k to 0x22343FF0 in the other ripper's ISO. Still have the original (January) CD that I'm free to ship out for investigation if possible.

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