Date: Fri, 17 Sep 1999 12:52:21 +0200 (CEST) From: Oliver Fromme <olli@dorifer.heim3.tu-clausthal.de> To: freebsd-multimedia@FreeBSD.ORG Subject: Re: Atapi CD audio ripper quality? Message-ID: <199909171052.MAA14465@dorifer.heim3.tu-clausthal.de>
next in thread | raw e-mail | index | archive | help
Daniel O'Connor wrote in list.freebsd-multimedia: > > Presumably, because it's a digital medium, there is only one "correct" > > version. Right? > > Thats true, but gsince CD audio has no checksum information you don't KNOW if > you're getting the right data. That's not exactly correct. "Red Book" CDs (audio CDs) have two layers of error detection _and_ correction information. These are should be handled by the CD-ROM drive and not be visible to the software running o the computer. (CD-ROM has an additional third layer of error correction, at least for mode1 tracks -- that's why a CD-ROM has a lower effective capacity than an audio CD.) However, if any non-correctable errors occur, the drive will usually _not_ signal an error condition to the host when reading an audio CD, but it will try to just send "similar" data to the host ("similar" regarding the perception of the human ears). Different drives have different algorithms for that. Usually you can't hear it if such corrections occur, unless the CD is severely broken which leads to skipping and "clicking". Of course, when reading CD-ROM data tracks, the drive should always report an error to the host if a situation occurs in which the digital data can not be reproduced 100% correctly. > > So how do I tell which setting (if any) is giving me the correct output? In your case, it rather sounds like a software problem. If it gives you identical output most of the time when using the same options, then the CD and your drive are probably OK. If you get different results when using different options, I'd say your "grab" software is to blame. On the other hand, most IDE CD-ROM drives require so-called "jitter correction", which your grab software must support. using different options might affect the way the data comes out in that case. My recommendation is, of course, to buy a decent SCSI drive and use a grab utility such as cdd or tosha. :) Regards Oliver -- Oliver Fromme, Leibnizstr. 18/61, 38678 Clausthal, Germany (Info: finger userinfo:olli@dorifer.heim3.tu-clausthal.de) "In jedem Stück Kohle wartet ein Diamant auf seine Geburt" (Terry Pratchett) To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-multimedia" in the body of the message
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?199909171052.MAA14465>