[LAD] USB audio on RPi3B+

[Jörn Nettingsmeier]

On 07/07/2018 05:47 PM, Fons Adriaensen wrote:
> Hello all,
> 
> Has anyone tried using multichannel USB audio on a Raspberry 3B+ ?
> 
> It seems to work perfectly (using zita-alsa-pcmi) with stereo cards.
> 
> When I try my RME Babyface (12 in, 12 out) in CC mode, the device
> opens without problems, but then Alsa_pcmi::pcm_wait() times out
> waiting for the poll fd to become ready. Timeout in pcm_wait() is
> 1000 milliseconds.
> 
> The same seems to happen with Jackd, which uses similar code.
> 
> Is there anything in the Pi's system or configuration that
> excludes multichannel cards ?

Not that I'm aware of. I've used an older Pi2 with a Gigaport HD+ USB 
device (eight RCA outputs at 44k1) with usable results for 5.1, and my 
KODI-based media center plays 5.1 movie content over (albeit over HDMI) 
flawlessly without breaking a sweat, ever.

If your quality requirements are modest you might want to look at the 
AudioInjector Octo I²S sound card for the Pi. I have two from an early 
series with known manufacturing defects, but if the developer (a very 
open-sourcey hardware hacker guy that is generally very helpful) has 
managed to get his chinese manufacturer to ramp up the quality control, 
it might be an option.
I did a few measurements with this card a while ago:
http://forum.audioinjector.net/viewtopic.php?t=3090

I have never used a professional USB multichannel card on the Pi since I 
don't own one (still stuck with aging ExpressCard Multi- and MADIfaces). 
But I'm trying to borrow one for testing becaus I have a similar usecase 
in the near future...


All best,

Jörn


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Jörn Nettingsmeier
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