Subject: Re: [linux-audio-user] Intermitent Xruns...
From: Mark Knecht (mknecht_AT_controlnet.com)
Date: Fri Apr 09 2004 - 21:21:18 EEST
Russell Hanaghan wrote:
> On Fri, 2004-04-09 at 04:41, Florian Schmidt wrote:
>
>>On Thu, 08 Apr 2004 23:35:50 -0700
>>Russell Hanaghan <hanaghan_AT_starband.net> wrote:
>>
>>
>>>Hi,
>>>
>>>I have set this laptop up in a CII docking station now that houses 2
>>>SBLive PCI cards. I have them chained with a modified .asoundrc file
>>>that gives me 4 ins and 4 outs. I have been using Ardour as the host
>>
>>Hmm, do you have any possibility to make these two cards sample synced?
>>i suppose not. therefore using them as multichannel device will fail due
>>to clock differences..
>
>
> I'm not actually using this setup for recording any tracks. Will it
> still be an issue just for monitoring?
>
> R~
>
If you intend to monitor out of both cards at the same time, then yes,
it's likely to be an issue. Each card is running from it's own clock.
Imagine one is running at 44101 Hz and the other is running at 44099 Hz.
Jack can only be in sync with one of those rates. If it syncs with the
fast one, then periodically the slow on will overflow. If it syncs with
the slow one, then periodically the fast one will run empty.
There is no way to solve this problem unless you 'sync' the two cards by
means outside of Alsa. I use ADAT clocking (not ADAT sync) and clocking
over s/pdif to sync multiple cards in multiple computers. It works
great...once you get it under control. The RME cards provide good
support for this and good software is available in both Windows and
Linux to see if things are in sync or just in lock.
Good luck,
Mark
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