Newsgroups: rec.video,rec.audio.misc,rec.audio.tech,rec.audio.opinion,alt.home-theater.misc,rec.video.dvd.players
Subject: Re: does quality of digital audio cable matter much?
References: <[email protected]>
	<[email protected]>
John Kotches  writes:

> > With data transmission, normally a checksum is used to check if there are
> > errors in data transmission, if there are, the data will be retransmitted.
> > Will this happen with digital cable?

Digital audio transmission on cables using S/PDIF or AES/EBU system
uses only checksum to check that the data is transmitted correctly.
If the data is not received correctly, the receiving equipment will
inform user that there is somethign wring with the connection. Because
the data transmission goes only to one direction (from source to
destination), retransmissions are not used.
 
> Nope.  The error correction code is Cross-Interleave Reed-Solomon.

This is the error correction code used in CD audio disks. 
The digital interface (S/PDIF) does not use anythign more complex than
just simple checksum.

> CD Audio and DVD are simplex constructed, that is to say the source
> (upstream) component transmits, the destination (downstream) component
> receives.  This isn't an RS-232 connection or a network :-)
> 
> Digital Audio (and video) decoding is a one-shot deal during playback --
> you get an unaltered sample or one that error correction has to deal
> with.
> For that matter, so is the encoding process.
> 
> > So why do people think that the quality of digital cable matter much, why
> > is the optical cable better than the coaxial one?
> 
> Most optical cables are made of plastic (ie TOSLink).  Go check the
> construction
> of your typical FDDI, 100-base FX, Gigabit Ethernet or FC-AL cable and
> tell
> me what it's constructed of.  It isn't plastic, it's glass.
> 
> Most all audiophiles will tell you that the Coaxial sounds better.  It
> could
> be an issue of the optical/electrical transducer introducing noise into
> the
> bitstream.
> 
> This debate will rage on for some time.
> 
> Anyway, I hope this helps.
> 
> 
> 
> 
> 
>  
> > Thanks.
> 
> -- 
> ************************************************************
> * A goofy Unix SA working for a large computer equipment   *
> * manufacturer and  services provider.  Opinions expressed *
> * are mine and not my employers.  jkotches@_pobox_.com     *
> ************************************************************

-- 
Tomi Engdahl (http://www.iki.fi/then/)
Take a look at my electronics web pages at http://www.hut.fi/Misc/Electronics/