Date: Mon, 02 Jul 2001 00:50:30 +1000 From: Stephen McKay <mckay@thehub.com.au> To: Joerg Schilling <schilling@fokus.gmd.de> Cc: ken@kdm.org, freebsd-scsi@freebsd.org, mckay@thehub.com.au Subject: Re: Problems reading burned CDs Message-ID: <200107011450.f61EoUw14742@dungeon.home> In-Reply-To: <200107011208.OAA16717@fokus.gmd.de> from Joerg Schilling at "Sun, 01 Jul 2001 14:08:18 %2B0200" References: <200107011208.OAA16717@fokus.gmd.de>
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On Sunday, 1st July 2001, Joerg Schilling wrote: >>From ken@panzer.kdm.org Sun Jul 1 06:01:32 2001 > >>On Thu, Jun 28, 2001 at 22:25:18 +1000, Stephen McKay wrote: >>> Actually, the difference is pressed vs burned CDs. >It is really a bad idea to use dd to read a CD. I think it's important that the raw CD be presented in a fully readable format. Then dd (and everything else) will work properly. >>> Is there any way around these problems with SCSI CD drives? > >Read README.verify & README.copy for a long answer.... I'm still digesting this information (from the cdrecord program, if anyone else is looking for them). I am assuming that 2 (or more) unreadable sectors are added, not that I lose 2 sectors of data. Right? >>Just out of curiosity, what did you use to burn the CD? cdrecord? One was burned with cdrecord (version 1.8, I think). Another by some Adaptec burner program under Windoze (unknown version of both). >There is no difference between a burned and a pressed CD. >There _is_ a difference between a TAO and a DAO CD. I am constantly surprised by the CD standards. Never pleasantly, either. >>It looks like the problem is a capacity reporting problem, possibly due to >>the way the burned CD was burned. > >There is no capacity reporting problem, the capacity is reported as documented >in the CD standards. We might either have to lie about the capacity (so that every reported byte can be read), or deal specially with the run out blocks (by faking them as nulls). >># cdrecord dev=1,4,0 -toc >>Cdrecord 1.9 (i386-unknown-freebsd4.2) Copyright (C) 1995-2000 Jörg Schilling > >A really old one..... Old software lives on! I'm still using 1.8, by the way. It also looks like you renamed your suite to: cdrtools. I expect the cdrecord port maintainer didn't notice. >>So now the question for Joerg -- do you know of any difference between >>burned CDs and "pressed" CDs (i.e. CDs produced commercially) that would >>account for the reported capacity of the burned CDs apparantly being a >>couple of blocks longer than the actual amount of data that can be read? >If you write in TAO, you get 2 run-out blocks (16 ??? on early Yamaha) >that are part of the TOC. I think we can ignore old drives if we can establish that the standard requires 2 sectors, and that most drives support this. Stephen. PS I checked ATAPI on -current, and now that the new accurate TOC code is in there, it also produces error messages on burned CDs using my Pioneer DVD reader. Progress! :-) To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-scsi" in the body of the message
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