Subject: RE: [linux-audio-user] Multiple (delta xx) cards
From: Mark Knecht (mknecht_AT_controlnet.com)
Date: Tue Jul 15 2003 - 19:32:40 EEST
>
> Would not a software/driver-solution to synchronize the
> clocks/adjust the drift be handy here? At least theoretically,
> somthing similar to ntp.
I don't think it's possible. My thoughts:
1) To the best of my knowledge sound cards tell you when the frame occurs.
Not only are the clocks different frequencies (by a small amount) but they
run completely unsynchronized, so the start of frame on one sound card could
be anywhere within the frame on the other, and I've never heard that this
can be controlled at all.
2) Most important, every time this conversation has come up on Alsa-Dev, my
impression is that the developers have less than zero interest in tackling
the problem since the Word Clock/ADAT clock/spdif clock solutions do exist.
Technically I think there may be solutions, but practically speaking the
problem get immense. Should you ever advertise that it works, you know you
are going to have some young guy with a weird pair of cards, like a SB-16
and a USB device, asking why it doesn't work for him. No one else will have
the same hardware, so no one will be able to debug why.
Heck, we can't even get Alsa drivers to work reliably for single cards -
why go after this issue? ;-) ;-)
Mark
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