Subject: Re: [linux-audio-dev] syncing soundcards
From: Iain Sandoe (iain_AT_sandoe.co.uk)
Date: Thu Mar 16 2000 - 06:22:07 EST
> On Sun, 12 Mar 2000, Iain Sandoe wrote:
>> You also have to be aware that they will *probably* not end up phase-synced
>> (as they would if you had a W-CLK) - because there might be several steps
>> between oscillator & sampling - which could be different on the two cards.
>> -- of course 2 off the same model, same version, same issue should be OK :)
>
> Then again, unless the drivers start the two cards at the same time
> (within less than a sample period), you'll get an additional phase
> error. You probably will get the cards within a sample or two, but
> you might have to use RTLinux + hacked driver to get beyond that. It
> might be possible, but personally, I don't think it seems to be worth
> the effort, unless it's for some system that is to go into mass
> production...
My comment was really aimed at the sub-sample issues.
I would hope (sincerely) that the linux sound implementation would aim to
allow multiple cards (with differing latencies ;) to be accommodated
I realise that this is quite hard (and therefore fun :)...
once (in the big, bad, closed-source commercial world) we had to sync up
eight cards - all with on-board dsp... to solve a real problem. For many
people several inexpensive cards (although I would hope with W-CLK at least)
- is a much better option than one biggie $$$ super-whizzbang.
one of the main limitations of the V** system at present is that it doesn't
(yet?) allow this.
perhaps this is really for PBD/et. al's discussion on stop/start issues
related to cards/channels.
Iain.
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