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Date: Sun, 19 Dec 2010 15:41:21 +0100
From: Polytropon <freebsd@edvax.de>
To: David Demelier <demelier.david@gmail.com>
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Cc: freebsd-questions@freebsd.org
Subject: Re: Unable to extract audio cd tracks
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On Sun, 19 Dec 2010 14:41:50 +0100, David Demelier <demelier.david@gmail.com> wrote:
> Thanks,
> 
> The handbook says we must `taste' the media, it works but it prints a 
> warning
> 
> markand@Melon ~ $ dd if=/dev/acd0 of=/dev/null count=1
> dd: /dev/acd0: Invalid argument
> 0+0 records in
> 0+0 records out
> 0 bytes transferred in 0.000132 secs (0 bytes/sec)
> 
> I just realized that using the block size for the same thing works :
> 
> markand@Melon ~ $ dd if=/dev/acd0 of=/dev/null count=1 bs=2352
> 1+0 records in
> 1+0 records out
> 2352 bytes transferred in 2.893379 secs (813 bytes/sec)
> 
> I propose modifying the following :
> 
> http://www.freebsd.org/doc/en_US.ISO8859-1/books/handbook/creating-cds.html
> 
> Make sure the appropriate files exist in /dev. If the entries are 
> missing, force the system to retaste the media:
> 
> # dd if=/dev/acd0 of=/dev/null count=1 *bs=2352
> 
> Then people who try that won't be surprised by the Invalid argument error.

A good idea - again one step into the right direction
of providing high-quality documentation.

In fact, I have never needed to "taste" the media in my
extraction scripts, but I now do realize WHY: Before using
dd bs=2352 to get the data, I did

	cdcontrol -f /dev/acd0 info

which prints out the TOC of the audio CD and, I assume,
makes sure the corresponding /dev/acd0tNN track files
get created; cdcontrol is part of the base system so it
should be possible to rely on its presence, at least on
FreeBSD.





-- 
Polytropon
Magdeburg, Germany
Happy FreeBSD user since 4.0
Andra moi ennepe, Mousa, ...