Trying to get video off stack of DVDs with identical directory error

[David Cooper]

I have a collection of DVDs written in a faulty model of Compacks DVD recorder (mostly +RW but some +R too). The first gigabyte of each disk will play on a computer and on other DVD recorders, but they always stop at that point, as does every data recovery program I've tried on them, so my guess is that the machine has set some field incorrectly, telling computers that the size of the disk is 1GiB, and all these recovery programs just believe it and don't look any further. However, I can copy an entire faulty disk using Nero which doesn't stop at the 1GB point, and I've finally managed to find a program that can make a complete disk image (Infrarecorder), thereby allowing me to access the entire content using a hex editor.

What I want to do now is extract the video from all the disks so that it can be written back to DVD properly, and in some cases be uploaded to the Net. The only way I can see of doing it is to copy and paste the VOBs into VOB files manually using the hex editor, if I can work out where they start and end, though I don't know if it's that simple. I've found what looks like a directory of content with things that might be start and end LBA addresses (stored in big-endian form), and with 2048 bytes per sector the values seem about right. Does anyone have any suggestions that might help me with this, because it would save a lot of time if I could simply find the directory fault and correct it.

[VirtualDoobMon]

Make sure the DVD's are finalized with your DVD Recorder. If you're using Nero and it works then copy each disc as a new image file (ISO,NRG) then mount the image with Nero Imagedrive, Daemon Tools or WinISO - more options at https://www.videohelp.com/software/sections/iso-image. If trying WinISO, simply launch the software then file>open and open the the DVD image you created with Nero and extract , or if you have the image mounted use Nero Recode for easy DVD > MP4 creation.

ISOBuster can work wonders have you tried it? If not i recommend you try it out. Also, it would be good to know if the DVD Recorder wrote the discs as DVDROM or DVD VR.

Hope this help.
J

[David Cooper]

Thanks for those suggestions - I'll have a look to see if any of them help. The +RWs are not finalised - they're still open for recording more programmes, but some of the +Rs are finalised and they suffer from the same fault regardless. The DVD recorder with the design fault also no longer works, so no further finalising is possible.

I've now tried ISOBuster and it lists all the files on the disk, but that doesn't guarantee it'll actually manage to extract them as all it's doing is reading the IFO - I can't try it out without paying $30, and I'm not going to do that unless I have a guarantee that it works first. It won't even let me do one experiment for free.

In the meantime though, I've managed to work out where the vobs start and end - I'd made an error in my calculations before and wasn't managing to line up on the right places, but at last I've been able to extract video files from way beyond the 1GB point in the disk image using the hex editor, then save them as .mpeg files and play them in VLC, so I have a workable solution at last that finally lets me get hold of all the files that were previously inaccessible (after many years of failed attempts). For anyone else needing to do this and who might happen upon this thread after Googling Compacks (a lot of these defective machines were sold, and I know someone else who had one which caused the exact same problem), the directory you need to work from is at byte address 1D9800h on each disk and contains entries (200h bytes in size each time) with a format providing you in each case with the start LBA address at offset 38h and the end LBA at offset 1Ch - they are both big-endian, so you can simply type the four bytes (8 digits) straight into the Windows calculator (in hex mode) in the order you find them, then you must convert from sector to byte address by multiplying by 800h (2048). Select the area from the start to end address each time, then copy, open new file in hex editor and paste into it, then save as .mpeg file and you're there. (I now notice that the date and time are also stored as BCDs in the directory at offset 7h [ISOBuster helped me work that out], and the filename is at offset 40h, but I can't work out what any of the other fields are for.) By the way, you'll probably need to save the disk image to the computer's internal drive rather than a USB drive because FAT32 is normally used on USB drives and can't hold a full DVD disk image as the maximum file size it can handle is 4GB while the image is 4.7GB.

The machine also had a nasty habit of trashing disks during the finalising process, so I'll now have to see if I can recover lost files out of them in the same way.