"Steve Jorgensen" wrote in message


If a card is neither syncing with nor doing sample rate conversion on
an incoming singl, you'll get pops because occasionally, a sample is
to there yet when the card's clock is ready, or a sample in the input
is skipped because the card's clock has gotten ahead. I think the
card can also just lose the signal for a few samples when this
happens.

I dunno, when my digital inputs are out of synch they sound absolutely
horrible - like noise.

When my digital inputs are synched properly they sound absolutely
wonderful, no tics or pops ever.

With sample rate conversion, to the extent that the sender and/or
receiver have timing jitter, there will be jitter mapped onto the
sound, and it will get muddy and unclear.

This would have to be restricted to real time sample rate conversion, right?

I always do sample rate conversion with PC software, and I've never seen
that kind of sample rate conversion of digital data add or subtract jitter.
I know of no theoretical reason why it would.

Jitter means the clock's
rate is not perfectly constant, so it gets a bit ahead, then a bit
behind with respect to real time, imposing a slight alternating time
compression/decompression.

That can happen at the point of analog - digital conversion. It can also
happen when you do real time sample rate conversion. Good reasons to avoid
both wherever you can, I guess.

On or about Sun, 01 Aug 2004 06:44:18 GMT, Logan Shaw allegedly wrote:

Laurence Payne wrote:
A justification might be the SB cards' inclusion of an on-board
sample-player engine - the SoundFont system. This would require to
work at a set sample rate.

Call me crazy, but why couldn't the SoundFont thing work at its
required sample rate and then have the sample rate conversion
convert the SoundFont's output to the rate that the D/A is going?
It doesn't seem like this would be a lot more expensive to build
given that either way you include stuff that does sample rate
conversion...

But if that is seen as a primary function of the card, it will sound
better if it has the short path. The digital in is probably seen as a
minor sideline that few gamers will use, and it's easier to blame the
other gear if it sounds lousy anyway.


Noel Bachelor noelbachelorAT(From:_domain)
Language Recordings Inc (Darwin Australia)