[LAD] USB audio on RPi3B+

[Fons Adriaensen]

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 ?

Ciao,

[Christopher Obbard]

Hi Fons,

Are you using a RT kernel at all?
Onboard i2s soundcards sound like a better option for multichannel, alas
the RPi only does 2 channels... unless you do some voodoo like transmitting
256 bits over two channels with a hardware divider... similar to how a
certain multichannel card does it ;-)



Cheers!

Chris Obbard
64 Studio Ltd

Post by Fons Adriaensen
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 ?
Ciao,
--
FA
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Linux-audio-dev mailing list
https://lists.linuxaudio.org/listinfo/linux-audio-dev

[Jörn Nettingsmeier]

Post by Fons Adriaensen
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

[Jörn Nettingsmeier]

Post by Fons Adriaensen
Hello all,
Has anyone tried using multichannel USB audio on a Raspberry 3B+ ?

Oh, and what distro are you running? I found that on raspbian I had to
do "rpi-update" at some point (which updates the firmware, some core
libraries and the kernel to a version newer than Debian stable)...