jack & full duplex possible

I was wondering if it's possible to use Jack?

Yes.

If yes, is full duplex (in & out) possible?

Yes.

What can I expect for the latency (less than 20ms, more than 100 ms)?

Don't know, I've never tested latency in Jack. ALSA gives me 6 - 7 ms.

If not, with Alsa is it possible to have analog in & analog out working at the same time?

Yes.

--

Ragnar

Wonderful! Is it better to use Alsa (less CPU, lower latency)? I was wondering if it is also a good idea to run everything in root (I know it's never a good idea normally) - but for getting the best performance out of the raspberry pi... Should I try to apply those modifications: http://wiki.linuxaudio.org/wiki/raspberrypi

Thanks!

Hi,

to get some midi stuff running for live events I patched a 3.12 kernel successfuly with realtime preemption patches from Ingo Molnar https://www.kernel.org/pub/linux/kernel/projects/rt/and merged the Wolson Audio card patches with it. The result is: You can plug in USB midi instruments into the raspberry pi and play them in realtime with hifi qualtity.

Hi Georg,

I guess it's not an easy task... Did you post more information about your setup somewhere? Could you spare some time to explain a bit more? Here's some questions:

• What distribution do you use
• Do you use Jack if yes what are the settings (period, nperiod, samplerate)
• Do you get glitches / drops
• Are you running X11 or headless
• What software are you using (amsynth, ...?)
• Do you use a special power supply (some people recommend some expensive one, I just have a basic cell phone charger 5V / 700ma)

Thank you!

Hi Pat,

it's not soooo difficult. Here some answers to yor questions:

• Ubuntu Studio 14.04
• yes, jack
• no glitches or drops!!!
• headless
• linuxsampler, amsynth yoshimi
• testing with easy acc powerbank  pb 12000A, and cellphone charger 5V / 1A

Some days ago I tested a setup with a tablet,a smartphone and another midi instrumented connected at the same time via wifi. It was possible to play all 3 without any glitches.

I'll post a little howto, a little video and the necessary patches when I've tested everything so far, that I think it's somehow stable.

Ubuntu Studio 14.04?

I don't see an ARM11 release:

Ubuntu Studio 14.04 LTS (Trusty Tahr)

If you want I can review your tutorial - trying to follow and add to it if something is missing (or adding how to run pure data for example). That would be nice!

yes, reviewing is really welcome! Thank you.

Answer: cross compiled on ubuntu 14.04

kernel  3.12.y and 3.14.y (from which only the first one works so far) for raspbian. Details will come soon.

Have fun

Georg

Ok make sense (using Ubuntu Studio for cross compiling and raspbian for the actuel distro)! In the meantime I found this tutorial: Talk Unafraid » Real Time kernels and audio on the Raspberry Pi - but I have to say that I would very much like to use your solution because I also want a similar setup (usb midi, pure data).

Keep in touch!

Hi Pat,

next weekend there will be more information on how to compile the 3.12 kernel with rt-preemption and wolfson drivers included on my website. Please be patient and

Have fun.

Here we go:

http://blog.georgmill.de/2014/04/26/compile-wolfson-audio-card-driver-for-kernel-3-12-y/

Have fun.

I have problem:

git reset --hard 4639d2b773b318d4b0409f67d3d5e73a513ba64b

fatal: Could not parse object '4639d2b773b318d4b0409f67d3d5e73a513ba64b'.

Hi Georg!

Thank you so much for this. Will try to find the time asap to confirm that it's working. With your permission, I will upload the rt-kernel with module so that people can simply do Step 53 (or maybe you already share the files somewhere)?

Talk to you soon

Hi Georg!

Thank you so much for this. Will try to find the time asap to confirm that it's working. With your permission, I will upload the rt-kernel with module so that people can simply do Step 53 (or maybe you already share the files somewhere)?

Talk to you soon