[LAU] running two soundcards with JACK

Arnold Krille arnold at arnoldarts.de
Mon Aug 17 08:45:26 EDT 2009


On Monday 17 August 2009 13:36:00 Julien Claassen wrote:
>    I just got a USB tape dec, which acts as an ALSA USB-audio interface.
> Now I wonder can I run both my PCI soundcard and the tape dec with one
> JACK, so I can use the deck to playback (digitalise tapes) and record? I'd
> also like to be able to listen live to tapes playing through the tapedeck,
> so just connect tape-output to soundcard playback.

Ah, Julien, please. You of all people subscribed here should know about the 
answers you will get:
 - No, its not possible. The soundcards sampling clocks have to be synced. And 
as long as we are not talking firewire or connecting the devices via 
spdif/word-clock, the only "solution" would be to solder a connection from the 
first soundcards crystal to the second soundcard. Which is impossible with two 
different devices probably using different crystal frequencies.
 - The only way this can work is by using a jitter-buffer doing live-resampling 
to work around the clock differences. And this doesn't sound good nor will it 
give you low-latency (the bigger the buffer, the better the result).

And all this was explained numerous times on this list and on lad :-)

Have a nice week,

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