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Hints, Tips and Solutions (Do NOT post requests for help here) If you have any useful general hints and tips for vintage technology repair and restoration, please share them here. PLEASE DO NOT POST REQUESTS FOR HELP HERE!

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Old 28th Feb 2012, 1:18 pm   #1
Diabolical Artificer
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Default Scratched Compact Discs.

I was trying to sort all of my CD's out yesterday. Most don't play all the through and most have broken cases.

Whilst trying to retrieve the playable tracks from the trash, I ripped a whole CD by mistake. The CD was scratched and most tracks were unplayable. I ended up with the ripped version playing perfectly all the way through. I've tried it on some totally trashed CD's - seems to work fine. Beats messing about with Brasso and toothpaste etc.

I haven't a clue what is happening, but it works. I'd appreciate your feedback.

A.
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Old 28th Feb 2012, 1:36 pm   #2
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Default Re: Scratched CD,s

Hi Andy,

This works because the ripping is not taking place in real time.

The computer or ripping program knows where it is up to within the time code, and so can attempt to read the data as many times as is needed (skipping to you and me in real time).

The computer only has to successfully read the data once (out of X amount of re-tries) IOW it is buffered, and then moves on to the next block of data, until the computer has obtained a continuous file.

We then play the now continuous file (in real time), and all is well.
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Last edited by Red to black; 28th Feb 2012 at 1:51 pm. Reason: sp
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Old 28th Feb 2012, 3:16 pm   #3
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Default Re: Scratched Compact Discs.

Ahh! The main thing it works. There has been a few posts on here re fixing poorly CD's. None that I can recollect about the 'rip fix'. I've been reticent about transferring all my music to the PC. Damned if I'm going to go the MP3 route.

I'll just rip the lot and bung them in the bin. I hope they can be recycled. I'm going back to vinyl anyhow. At least that way I won't have lots of broken CD cases driving me bonkers. I'll save you the rant on CD case 'design'.

Andy.
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Old 28th Feb 2012, 3:58 pm   #4
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Default Re: Scratched Compact Discs.

Also when ripping CDs, quite often they are read at much higher speed than they'd be played at for listening purposes. So the scratched area can get read a hundred times if needed with slightly different lens positions and it might be able to get a good bit of data from it.

Of course it may just give up and insert an interpolated (or even just duplicated) data value for that sector if it can't read it.
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Old 28th Feb 2012, 4:56 pm   #5
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Default Re: Scratched Compact Discs.

Why not rip your CD's to the PC, and then reburn them to blanks?
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Old 28th Feb 2012, 7:34 pm   #6
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Default Re: Scratched Compact Discs.

I'm curious as to how most of a CD collection can become too damaged to play. The odd one might meet with an accident, but the whole lot?
If they can be read by a PC, they can be re-polished; there's a whole industry doing so with second-hand discs in order to resell them.
As far as ripping goes, there is a 'subjectivist' view that ripped CDs, even when new, sound better than the original, but that's another discussion!
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Old 28th Feb 2012, 7:34 pm   #7
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Default Re: Scratched Compact Discs.

Might work for the cost of a cd or two.
http://www.ebay.co.uk/itm/PROCARE-PR...item2eb56af5b0
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Old 28th Feb 2012, 7:44 pm   #8
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Default Re: Scratched Compact Discs.

Quote:
Originally Posted by Dr Wobble View Post
I,ve been retacent about transfering all my music to the PC. Damned if I,m going to go the MP3 route.
Who said anything about MP3. You can rip to uncompressed WAV files if you like. Then you can use lossless FLAC compression if you want to squeeze the data by about 2:1. I sometimes use Audiograbber http://www.audiograbber.org/ If I remember correctly, the standard settings give you both WAV and MP3 files for each track.
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Old 29th Feb 2012, 1:41 am   #9
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Default Re: Scratched Compact Discs.

There's a useful (free) program out there, called Exact Audio Copy, which reads each sector many times, and makes a "majority decision" on what it reads. It can thus make a best guess of damaged parts of the disk. It generates a wav, which can be burnt to a new CD, or converted to an mp3.

http://www.exactaudiocopy.de/en/
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Old 29th Feb 2012, 8:39 am   #10
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Default Re: Scratched Compact Discs.

Quote:
Originally Posted by Dr Wobble View Post
I,ll just rip the lot and bung them in the bin.
If you're really going to throw them all away, make sure you've got solid back-ups of all the ripped files...
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Old 29th Feb 2012, 11:08 am   #11
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Default Re: Scratched Compact Discs.

Quote:
Originally Posted by tedzed1 View Post
Why not rip your CD's to the PC, and then reburn them to blanks?
The danger with that is that the reflectivity of CD-R is about 25% of that for stamped silver discs. That is OK with relatively recent CD players with chipsets and control systems designed with CD-R in mind. But older players can give problems with reading CD-R.

Craig
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Old 29th Feb 2012, 6:28 pm   #12
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Default Re: Scratched Compact Discs.

I've recovered a few damaged cd's by ripping them at very slow speeds so yes it can work.

Years ago when cd's were first being promoted there was a (Philips?) tv short film that showed a guy eating his dinner off a cd using a metal knife and fork. Afterwards the cd was put in a bowl of washing up liquid and then played perfectly on a cd player. I thought at the time that this was a bit far fetched.

This must have been around the late 1970s. I don't know if the film would still be available anywhere?
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Old 29th Feb 2012, 8:47 pm   #13
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Default Re: Scratched Compact Discs.

Ah yes "Perfect sound forever" was Philips' slogan when they launched CD. And as compared with black vinyl it sounded like a bag of hammers being rattled while someone scratched the back of your eyes with a toothpick.

It has take quite a while for CD, or digital sound generally, to get to the stage when it is as good as analogue. I haven't listened to records for at least a decade - but back in the early 80's, oh dear oh dear - I was reaching for my deck.

The other problem was digital mastering. CD's recorded in DDD back from the early days of CD sound pretty dreadful - which is a shame because lots of excellent music and performances (like Pavarotti's) sound really dreadful because the recording is plain bad.

Craig
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Old 4th Mar 2012, 11:15 am   #14
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Default Re: Scratched Compact Discs.

Regarding the OP's problem, what happens if you pop the CD in the computer's drive and just play it? Could it just be that your PC's optical drive is in better fettle than the machine(s) that skip and jump?
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Old 4th Mar 2012, 12:17 pm   #15
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Default Re: Scratched Compact Discs.

I have just read all this thread on saving music off scratched CDs and would very much like to know what you mean by "ripping "?
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Old 4th Mar 2012, 1:16 pm   #16
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Default Re: Scratched Compact Discs.

Quote:
Originally Posted by line sync View Post
would very much like to know what you mean by "ripping "?
Copying a cd usually to MP3 tracks.
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Old 5th Mar 2012, 12:31 am   #17
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Default Re: Scratched Compact Discs.

Thanks Dave, I'm not up to speed with these modern terms.
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Old 5th Mar 2012, 1:25 am   #18
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Default Re: Scratched Compact Discs.

Somewhere on a VHS cassette I have a recording of a circa 1990 open university mathematics program that showed how the (proposed) error correction algorithms for CDs would allow error-free reproduction. This was demonstrated with a CD that had had 4 radial sawcuts made in it. I think that they decided that implementing the error-correcting algotrithm was uneconomic, hence the unplayablilty of actual CDs tha have relatively minor scratches.
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Old 5th Mar 2012, 8:34 am   #19
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Default Re: Scratched Compact Discs.

Remember that while the playing surface of a CD is very tough and can have scratches polished out the label side is fragile. Just writing on it with a ballpoint pen can be enough to cause damage. The reason is that the aluminised layer is only just below the lacquered surface.
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Old 5th Mar 2012, 9:10 am   #20
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Default Re: Scratched Compact Discs.

Quote:
Originally Posted by emeritus View Post
Somewhere on a VHS cassette I have a recording of a circa 1990 open university mathematics program that showed how the (proposed) error correction algorithms for CDs would allow error-free reproduction. This was demonstrated with a CD that had had 4 radial sawcuts made in it. I think that they decided that implementing the error-correcting algotrithm was uneconomic, hence the unplayablilty of actual CDs tha have relatively minor scratches.
The "Red Book" CD standard mandates very strong error correction which must be implemented in order to make even an apparently pristine CD playable. The raw, uncorrected error rate is so high that this must be done.
See this thread https://www.vintage-radio.net/forum/...highlight=circ

John
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