Re: Live mixing with Linux - State of the art 2018
Posted: Sun Jan 20, 2019 3:38 pm
Of course, if your system gives no xruns or problems - there's no need to fix it.Musicteacher wrote:Could you point out in which situations exactly you did get xruns with a non-realtime kernel?
I had used a 64 bit buffer, and I had no xruns during that gig except when loading / saving files, not while playing.
As I said, using network for remote-acces via vnc would be interesting for me, would, for instance, a realtime kernel prevent the network from interrupting the audio-processes?
Or, to put it differently: I will try a realtime kernel as soon as I run into unsolvable problems with the standard kernel (I use arch standard kernel, which seems to be better suited for realtime anyway, though not a real realtime kernel if I understand correctly).
Thanks for your input!
I'm not saying everyone should get a realtime kernel or even that it is necessary for live gigs. Just that this is the case for me.
I can give some thoughts on it here:
1/ I can generally put more plugins into a live setup before xruns appear with a rt-kernel. When editing projects this is of little relevance, but on stage that difference is of course important. Trying to stay at frames/period 64 in the cases of "this vocal needs a compressor and a reverb, the guitar sounds better with. . ., and then this synth eats some cpu" and suddenly there are a few plugins at play - my experience is that a low latency kernel more easily becomes wobbly, while the rt-kernels I've used behave more trustworthy. But i've never used arch standard kernel for audio, my audio experience is limited to Debian/Ubuntu related kernels.
2/ this whole thing started for me some years ago when I was doing a perfomance on national radio, in front of an audience. I was using Ubuntu Studio at the time, with their stock low-latency kernel. Xruns were always near, but I thought it had to be that way. Suddenly while we're playing, all sound stops. For 6 seconds. Dead silence. Not a sound. 6 seconds are an eternity of time when you're on stage in the middle of a performance and sound breaks off. Suddenly everything came back like a wall, xruns were running down my screen, it really was a nightmare for me. I was so ashamed and stressed out. Of course this was not only related to the kernel, but after this experience I started optimizing my system more carefully, and started using a rt-kernel. The improvement in stability when using a rt-kernel amazed me. Some time after I did a similar performance with a rt kernel, and not a single xrun appeared for the 4 hours my computer was on.
Using a rt-kernel actually gave me back the trust for using GNU/Linux live.
3/ When it comes to vnc, even if that would work (I know nothing about it), I'd personally feel a lot safer sending the sound by cable to this other computer or to a mixer. Wired from audio interface to audio interace. When doing live stuff, I prefer to turn off all network, so that it doesn't influence the sound stability. But hey - testing it wouldn't do any harm. It might work just fine.
Actually, the whole question of rt / low latency-kernels is rather easy to check.
Install a rt-kernel without getting rid of the low latency (or standard) one. Compare them, try different projects on them, test how heavy a workload they can take. See which one works the best for you. Trying out a kernel is really rather easy, you lose nothing by it. Then pick the one you trust the most.