[mythtv-users] Problems with alsa & spdif & myth

David myth at dgreaves.com
Wed Apr 7 07:34:33 EDT 2004

>> some HIFI people agrues that, when you use optical the signal comming 
>> from electric components inside you pc, will need to be converted to 
>> a optical signal, transmitted over the vire, and converted back into 
>> an electric signal in the other end. And the further argue that such 
>> an conversion might be lossy and hench deteriorates the signal.
> Yeah, right. Audiofiles often state this, and usually they have no 
> idea what they are talking about. Media conversion of a digital signal 
> doesn't cause quality loss, quite often it's the other way.

*If* you have error detection and correction - and I don't think a PCM 
stream does.
Also, I've read that the (SPDIF) optical signal degrades over a 
surprisingly short distance (~1m) but it is less susceptible to 
interference whilst it does so.

(BTW I wouldn't be surprised to hear an audio file state it - and I'd 
agree that they don't know what they're talking about
but usually it's audiophiles that state it about audio files ;) )
(sorry - couldn't resist!)

(PS I gave up being an audiophile a while back - but there is a lot more 
to sound quality than engineering)

>> however IMHO I choose optical as I _THINK_ (subjective personal 
>> opinion :) the noise being trnasfered from the PC is more anoying 
>> than potential  loss of quality due to conversion.
> Always choose optical if possible, but beware of bending optical 
> cables much, because they are a bit more fragile (especially glass 
> fiber, not as much the more common plastic ones).

 From my dvd player optical sounds *slightly* different (not as sharp on 
bass for me) IMHO.
I'd use optical from my PC if available as I think there is far more 
chance of noise/hum from a PC.

<sigh> still not gt it going - it's on my todo list though...


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