[PlanetCCRMA] multiple card synching

Mark Knecht Mark Knecht <markknecht@gmail.com>
Thu Feb 24 05:50:02 2005

On Thu, 24 Feb 2005 12:01:32 +0100, Michele Spinolo
<michele.spinolo@tin.it> wrote:
> Hi guys,
> I'm running a system based on PlanetCCRMA FC1 2.4.26 kernel, with 2 Terratec
> EWS88D and 1 Terratec EWS88MT installed.
> This system is connected to a source which is capable of sending audio data
> on 3 stereo s/pdif coaxial cables, wich are plugged into s/pdif coax inputs
> of my 3 cards.
> The three s/pdif cables should be synched: in fact the s/pdif transmitter is
> only one for all 3 s/pdif outs on the source.
> Now I use this system for real time convolution running BruteFir: everything
> runs fine while I use only one card, but when I run convolution on more than
> 1 card I got some "clicks" on output.
> These "clicks" are often releated to not clock synched cards, but they
> should be synched: they are setted to get sync signal on s/pdif input.
> EWS cards allow to set a master card and up to 3 slave cards, where slave
> cards get sync signal from the master card: unluckily this is not possible
> under Linux, but only under windows.
> So I was wondering if someone could give a hint to try to solve the problem
> before I keep the solder in my hand and try to follow this guide:
> http://www.djcj.org/LAU/quicktoots/toots/el-cheapo/
> Thanks!
> Michele

   There area  couple of issues here for you to look into:

1) On your remote source with 3 spdif outputs are you completely sure
that they are in sync with each other when transmitting? It would seem
like a reasonable assumuption but it may not be true. Check the specs
on that device very carefully. Read forums, etc. for that device (what
is it?) and see if others have had similar results. (good or bad)

2) Doing the soldering routine sould be the last thing you do. I would
think that if the card has the cabaility of being synced via software
then the developer for that driver should be contacted. On the RME
HDSP cards we have an application that gives us this capabiltiy. Talk
to the driver developer and see what you need to do to get him to
build this capabilitiy.

   Good luck getting it solved. It sounds like interesting stuff you're doing.

- Mark