[Jack-Devel] Cannot combine audio devices with more than 64 channels

[Adrian Knoth]

> Let's assume that you configure Jack to use soundcard A, and then
> run zita-j2a using card B, word-cloclk synced to A, to have
> additional outputs. 
> 
> Zita-j2a is just a Jack client like any other. Even if cards A
> and B are configured to use the same period size (this is not
> required) the period timing of B w.r.t A is completely random.

In theory, the RME cards/driver has SNDRV_PCM_INFO_SYNC_START. I've
never used it, but my understanding is that you can start multiple PCM
streams at the same time.

No idea if this would work across multiple cards, given that you have to
flip a hardware bit in every card individually which may introduce a
small offset. Maybe it's small enough to be sub-sample, so the buffers
are perfectly aligned.

Clemens might know. (CCed; Clemens, background is: multiple MADIfx cards
combined, 192 channels each. The PCM compound device only allows for
N*64 (this could use a fix), hence the discussion about workarounds)

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