Rpi2 and jackd: xruns

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Rpi2 and jackd: xruns

Post by cyberic » Sun May 14, 2017 8:02 am


I am testing the stereo soundcard to see if it could be used for live performance, with jack.

I use dtoverlay=i2s-map, on a Raspbian.
Kernel: Linux raspberrypi 4.9.24-v7+ #993 SMP, on a Raspberry pi 2

Below are the different configurations I tested.
I stress the pi with 'stress-ng --cpu 4 --fork 4 --timeout=10s'

I use the pi through VNC so the network card is used as well.

I didn't notice I had to add dtoverlay=i2s-map to my config.txt, and without it I was having some freezes of the Pi2.

With dtoverlay=i2s-map, it is better. I get some xruns, but at least the Pi doesn' t freeze and I can restart jacks.

I understand it is normal to get some xruns, but I though that after a few, the soundcard would be able to recover and keep operating nomally.
Am I wrong?

When I got xruns, it starts by ony one, then bursts of 300 to 500 xruns per second.
And even after reducing the load, jack cannot recover, xruns don't stop.

If I can help you in any way, or add some debug, please tell me.

With all the combinations given below, I got some 'unstoppable' xruns.
In logs, I got: bcm2835-i2s 3f203000.i2s: I2S SYNC error!

f/p = frames/period
p/b = periods/buffer

with sample rate: 48000
f/p p/b
256 2

sample rate: 96000
f/p p/b
128 3
128 4
256 2
256 3

Thank you

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