Take the 2-minute tour ×
Super User is a question and answer site for computer enthusiasts and power users. It's 100% free, no registration required.

I've a badly scratched VCD whose content can't be copied to hard disk. My OS is Windows 7 Ultimate x64. Windows can't copy the 750 MB video file. I also tried CDCheck and Recover Disc. Both of them are terribly slow to copy the content as there are too many scratch and thus too many read errors. For example Recover Disc was able to store only 6% after 1 hour. As the copying was taking so long time I didn't finish it.

Surprisingly, the video file can be viewed smoothly by VLC or jetAudio. I don't understand - if there are too many scratch on the CD so that Windows and other software can't copy it, how the media players are able to play it? If they can play it, the content should be recoverable. How can I recover it (copy it to hard disk)?

share|improve this question
1  
I have very good luck using Ultra ISO to copy data from damaged discs using "extract"....ezbsystems.com/ultraiso –  Moab Sep 2 '11 at 16:56
    
@Moab, thanks. i'll try it out. –  Donotalo Sep 2 '11 at 17:23

7 Answers 7

up vote 14 down vote accepted

Since your question seems more to be 'How can this be' (and not "How can I copy this disk") I'll try to answer to that:

When viewing video it's OK to skip/drop corrupted frames, similarly this also applies to audio.

They can get away with this because your brain can make up the difference (in minor cases) so it still appears fine to your eyes/ears. Even noticeable corruption, like a few funky frames/scenes/artifacts, still doesn't render the video 'unwatchable' (you can still comprehend what's going on).

But, when you try to copy the file, it wants to copy all those bits, exactly as they appear, regardless of the content.

If some of those bits are corrupted in a non-readable way then it can't 'copy' it, and so the job of copying it fails.

As to recovering/copying it, I think you've got what you need, you just need to wait. For example, when a colleague of mine was recently recovering video from a scratched DVD-R (which played fine, but he needed a copy of it), similarly to what you say you tried with Recover Disk, it took multiple DAYS for it to finish up and give him a version he could view and copy.

share|improve this answer

You can try CopyCat, it has features designed to work on heavily damaged media.

share|improve this answer
    
Warning--it installs garbage. –  Loren Pechtel Jul 9 at 14:51

Another option would be a CD/DVD repair kit. They sand down the surface of the optical media to an even level, then buffs it smooth. Ive used the Skip Doctor before and can say it works.

share|improve this answer

If you can play the video with VLC, you should also be able to dump the video as it is played.

One way to do this is to go to: Media -> Convert/Save, select the video file, choose "Convert", enter the destination, and select "Dump raw input".

share|improve this answer
    
this is what i'd suggest before anything else. If it plays, it converts. –  Journeyman Geek Sep 2 '11 at 23:31

What you need is a recovery tool, not a disk copying tool. The CD standard uses error correction coding, called CIRC, that allows relatively minor errors to be corrected. CIRC also allows severe errors to be detected, but it cannot correct them. This is still useful when playing back the CD, because the software can conceal the errors by dropping frames.

When it comes to copying, it's a different story. One of the primary differences between analog media (like most tape formats) and digital media is that using digital technology, you can make 100% perfect copies, without error. In contrast, analog copies always contain error, in the form of noise. When your disk copying software sees that an unrecoverable error is in the media, it correctly tells you that it cannot make a copy, because that would imply 100% perfection.

Disk recovery software cannot fix all problems, but it can use special techniques to try to fix errors with some probability. Often times, this works by using special hardware modes, by re-reading data multiple times, and using other special techniques. This takes time.

If you just want a good-enough copy, try to find disk copying software that allows you to disable error protection.

share|improve this answer

Many local game stores have a CD polisher - see if you can locate one and ask them to run your disc through their machine. In the UK, Gamestation do it for a couple of pounds.

share|improve this answer
    
This kind of services aren't available in my country. Thanks for the information. –  Donotalo Sep 3 '11 at 4:49

Dont need those "kits". Just use car polish or car wax. Polish the scratched surface well and it should work after that.

share|improve this answer

Your Answer

 
discard

By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.