Arny Krueger
August 2nd 04, 11:53 AM
"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.
> 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.