Date: Wed, 23 Sep 1998 20:33:46 +0200 (MET DST) From: Luigi Rizzo <luigi@labinfo.iet.unipi.it> To: mike@smith.net.au (Mike Smith) Cc: netmonger@genesis.ispace.com, oppermann@pipeline.ch, abial@nask.pl, hackers@FreeBSD.ORG Subject: Re: backport of atapi-cd to -STABLE Message-ID: <199809231833.UAA07940@labinfo.iet.unipi.it> In-Reply-To: <199809232014.NAA03628@dingo.cdrom.com> from "Mike Smith" at Sep 23, 98 01:14:40 pm
next in thread | previous in thread | raw e-mail | index | archive | help
> > Jitter correction is for the crappy (older) CD-ROMs.. Some sort of a thing > > about the lens jittering during use that can cause problems with generating ... > Jitter correction has to do with fixing up the raw audio data, it has > nothing to do with the digital side of things. "len jitter" wouldn't > affect the audio data - when a bit comes off the disk it's either a 1 > or a 0, and it either passes the DRS check or it's fixed if it's wrong. to clarify, the so-called jitter correction in "cdd" serves for those drives whose firmware does not guarantee that the data you get from the disk are for the block you requests and instead could give you data for a nearby block (presumably, but this is just an assumption, from time to time the firmware misses a block and passes you the next one). the way to do the correction is to read overlapped sections from the disk and compare the boundary block to make sure that they overlap as expected. On a drive that does not need jitter correction you lose a lot of speed. cheers luigi To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?199809231833.UAA07940>