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catnap

Member

Registered: 2016-10-03

Posts: 131

[SOLVED] How to rescue audio CD

A box of about 30 used audio CD's that I purchaced online turned out to be
too worn and scratched for my audio set to be able to play the CD's without
interuptions. I have tried to repair the CD's by brushing them clean but
without much success. As a last resort, I'm trying to copy the content
to my hard disk in an image file, which is not against the law in my country
if the media does not use DRM. The tool that I use is ddrescue:

ddrescue -b 2048 /dev/sr0 /home/me/image.iso /home/me/image.log

Unfortunately, the output of the command reveals that nothing was copied.
Also, the size of the created image file is 0 B. Does this indicate that
the CD was copy protected? Is there a tool that would help me find the
copy protection status of the CD?

Last edited by catnap (2016-11-08 16:54:06)

ewaller

Administrator

From: Pasadena, CA

Registered: 2009-07-13

Posts: 19,771

Re: [SOLVED] How to rescue audio CD

CDs are not generally DRM encumbered. Audio CDs do not have a file system (per se), but you can have hybrid CDs that have both an iso file system and separate audio data.  One notable media company, which I continue to boycott, thought it a good idea to distribute malware infected hybrid CDs that infected Windows PCs to interfere with file ripping and to send 'telemetry' back to the corporate entity.  So, you are basically correct about the lack of DRM -- but they also generally don't have a file system.

tl;dr -- ddrescue is probably not the right tool for audio CDs.  It is the right tool for CDROMs

Have you tried any of the cd ripping tools that are available?

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frostschutz

Member

Registered: 2013-11-15

Posts: 1,417

Re: [SOLVED] How to rescue audio CD

cdda2wav, cdparanoia, ...?

catnap

Member

Registered: 2016-10-03

Posts: 131

Re: [SOLVED] How to rescue audio CD

cdda2wav, cdparanoia, ...?

The first of these programs is what I needed. The second one would likely do the trick as well.

Wild Penguin

Member

Registered: 2015-03-19

Posts: 320

Re: [SOLVED] How to rescue audio CD

I definitely recommend using cdparanoia. With cdda2wav, you may get errors in the files, especially with scratched CDs! The CDDA standard has very little error correction, and/or some (nearly all!) optical drives do not report the error correction checksums (that could be used to spot some/most of the reading errors) - don't remember the details. The bottom line is:

You may (read: quite likely will with scratched CDs) get errors - without any error message at the copy - which you will notice only after you play the resulting wav files back, and sometimes it may be so subtle that you may notice it at the Nth replay - and it may still be annoying when you finally notice it.

The only real workaround is to copy the CDDA tracks multiple times from the CD and compare the results (as an identical error occuring multiple times is rare). Cdparanoia (and others) automate this task, but cdda2wav is not one of them. I think per default cdparanoia uses 4x verification (No, it is more complicated than that).

Of course, if you are not that pedantic about the quality and don't mind a few clicks here and there, you might not care (but sometimes cdparanoia can repair quite a lot of clicks!).

As a bonus, some frontends (that can use cdparanoia) can facilitate renaming the resulting wav files according to data input by the user or online databases. I use abcde. Of course if your goal is to burn a CDr copy of the original, this may be quite useless.

P.s. This is coming from someone who used to copy all CDs in his collection onto hard drive for ease of playback and also as a poor stundent also those sometimes very, very scratched CDs loaned from the local library or friends (which was and still is legal where I live). This behaviour has diminshed quite a lot after some streaming serrvices surfaced, however.

EDIT: Reading the cdparanoia FAQ, I think the above may not be totally accurate. Some of the read erros (I and other users have experienced 10-20 years ago) may have been due to the fact that the drives back in the day were buggy. But I have no information whether current drives have or do not have such bugs (as these days I have way less need for CDDA ripping). But that doesn't mean cdparanoia would be useless with scratched CDs because the poor error correction features in the original CDDA spec. These days, cdda2wav might work better than it used to. In any case, you have been warned - in case you care about the quality of the RIPs...

Last edited by Wild Penguin (2016-11-08 23:06:16)

NoSuck

Member

Registered: 2015-03-04

Posts: 157

Website

Re: [SOLVED] How to rescue audio CD

Red book audio is not the perfect set of 0's and 1's one might think it is.  It is an error-tolerant stream, modeled after media that came before it (records, cassette tapes).  You could play the same CD twice in the same player, and different data could be sent to the DAC.  Such differences are usually imperceivable to the human ear.

That is why a simple cp command does not get you raw wave data, and that is why we have special software to rip audio CDs.

Anyway, cdparanoia invariably fails on my hardware to rip the last tracks of audio CDs.  I have troubleshot the issue through official channels, and no solution was found.  I therefore recommend rubyripper.  It is similar to EAC.

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Texbrew

Member

From: The Lone Star State

Registered: 2016-02-09

Posts: 580

Re: [SOLVED] How to rescue audio CD

Thanks for these suggestions. It's been a while since I used any CD tools. It would be nice to extract cleaner audio from some of the mis-handled discs in my collection. Will check out rubyripper first.

tex

teckk

Member

Registered: 2013-02-21

Posts: 519

Re: [SOLVED] How to rescue audio CD

One more suggestion. If a CD-DVD is scratched, you can use some toothpaste and a clean soft damp rag to buff some of the scratches out. Maybe enough to allow you to get the data/track off of it. If the optical disk is starting to separate a little on the inside then nothing will help. Toothpaste has a mild abrasive in it. I've made several dvd's from a well known company read better by rubbing it good at the sink with toothpaste and a damp rag, that otherwise would not read. It will put very micro fine new scratches on the surface but it but will level out the deeper scratches and take the fog off of the outside layer if it has one.

Last edited by teckk (2016-11-13 18:16:14)

Wild Penguin

Member

Registered: 2015-03-19

Posts: 320

Re: [SOLVED] How to rescue audio CD

You could play the same CD twice in the same player, and different data could be sent to the DAC.

I agree with most of what you say (and perhaps I'm just too precise on the little bits here), but this just does not seem right... if I was getting different data on subsequent reads of the same audio CD, I'd consider either the CD or the player/drive (or both) broken (cp command is also irrelevant here, since it is not a file system to begin with). While it is true that small errors migh not be perceived by the human ear, it does not change the fact that all CDs (of the same publication) are identical (in terms of 0s and 1s) when they leave the factory (also, it does not justify CD players that do not produce consistent stream of bits on subsequent playback of CDs in good condition - even if it was not perceived by the listener, IMO).

As for the different rippers - I also remember using EAC back in the day (when I still used Windows), and have only positive memories of it. If rubyripper is similar, then it is probably worth a shot (haven't used it personally). It seems that cdparanoia and EAC use a different approach to rip the audio (with the same goal: files representing 100% of what is actually on the CD). But a lot of "dumb" rippers produce errors, or at least do not give any error messages if the rip has actually failed.

Texbrew

Member

From: The Lone Star State

Registered: 2016-02-09

Posts: 580

Re: [SOLVED] How to rescue audio CD

Though hesitant to post again in a thread marked as solved, here goes.

@teckk, I guess when it comes to trying to revive scratched CD/DVD media, doing something is better than doing nothing, as there is a small risk involved when cleaning them.

I have had small successes using mild liquid dish detergent, rubbing gently - no cloth, rinsing with water, pat it dry with a lint-free cloth (I can't even type that with a straight face right now, but I'm being serious). Works well removing fingerprints, can't say if it helps with scratches.

I will remember your toothpaste hint next time for scratched media. Thank you.

tex