Subject: Re: Ripping CDs with an old player
To: None <port-i386@netbsd.org>
From: der Mouse <mouse@Rodents.Montreal.QC.CA>
List: port-i386
Date: 08/28/2002 01:05:20
>> To rip audio tracks, you need a drive that is willing to take the
>> 2352-byte sectors from audio tracks and pass them back to the host
> to be exact it doesn't read sectors, as with audio there are no
> sectors, just stream of data without any sector marks.

That doesn't sound right to me.  What's your reference?  Certainly back
when I set up cdparanoia all the disc documentation I found spoke of
real 2352-byte sectors, and the FAQ.txt file in the version I have
installed here says that

	[A] CD, audio or data, uses 2352 byte sectors.  In a data CD,
	304 bytes of each sector is used for header, sync and error
	correction.  An audio CD uses all 2352 bytes for data.

It has a description of how the subchannel informaiton allows you to
tell where you are to within a few sectors, at most, but it's fairly
length (ca. 50 lines), and not really directly relevant, so I won't
quote it here.  I'll be happy to excerpt it - or send the whole file -
to anyone who asks, but off-list.

> so drive just reads sequence of data it gets near lens, without being
> sure next "sector" will be just after first.  that's why CD paranoia
> has correction procedures that ensures data read is really sequential

There *is* subchannel info, allowing the drive to tell where it really
is within a few sectors - if it's smart enough to pay attention to it.
Cheap drives often don't.  One of my drives doesn't need jitter
correction; as far as I can tell, if you tell it to read starting at a
given point, it will hit the boundary you asked for dead on, every
time.  (Assuming a clean disc, of course.  Media damage will, of
course, cause problems.)

cdparanoia has jitter correction for dealing with drives that are too
cheap to bother with figuring out exactly where they are when reading
audio data, or at least with using that information to return exactly
what the host asked for.

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