[Alsa-user] Re: [ardour-users] Capturing audio with 2 delta1010lt's (chapter 2)

[Florian Schmidt]

On Mon, 24 Jan 2005 18:51:23 +0100
derek holzer <derek at x-i.net> wrote:

> You'll probably get more feedback from the various lists, but the 
> problme is definitiely with the sync. What usually happens when you use 
> two different soundcards is that they gradually drift out of sync with 
> each other, causing a crash. The keyword to search the ALSA list for is 
> "el cheapo", as in "the el cheapo myth", whereby several low cost 
> soundcards can be theoretically synced together to make a multichannel 
> DAW. The only successful implementation I have heard of for this is to 
> physically connect the crystal driving one of the soundcards to all of 
> the others, which slaves them all to the main chip. I haven't heard of 
> using spdif for this, although nothing screams out at me that it 
> wouldn't be possible.

Delta  cards (at least some of them) can use an external sampleclock
(either from spdif or from wordclock (some models i think)). So the only
problem is to start both of them at very close points in time.

I don't know how ALSA handles starting the playback/capture on each of
the soundcards bound together by a "multi" pcm plugin, especially if it
makes any priovisions to start 'em both close in time to each other..

Flo

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