I am experiencing some popping/crackling issues with my USB audio device and as suggested in the Renoise Linux FAQ and some posts I found on the internet, I tried disabling Compiz effects. Although I didn’t experience any pops during the brief time I was testing, I found Renoise to be effectively unusable due to atrocious graphics performance: the volume meters are updating at about 5 FPS, and dragging the scroll bars in pattern editor or matrix causes extreme lag.
This is very surprising to me because normally I would expect compositing window managers to reduce display performance, but it seems in my case it is actually necessary. Which is a bummer, because it potentially means I have to choose between awful graphics or audio popping, assuming that it does actually fix the audio problems in the first place.
There is more to this than only the window managers. But indeed ( Linux, Renoise And Choppy Sound ) window managers can be quite a PITA when it comes to audio performance.
But also Pulse audio doesn’t seem to be the most perfect audio engine to use for real time audio unfortunately.
I’m not currently eager to drop Ubuntu Studio 7.04 or 7.10 and that is quite some versions back, but these use ALSA and Jack solely without the whole load of crap we don’t need (including Pulse audio).
That post is consistent with my experience, the popping has only become a noticeable problems since switching to GNOME. It does sound like KWin provides the compositing with a lower impact on performance.
This doesn’t explain why the graphics performance is so bad with compositing switched OFF, however. Maybe Metacity is just crap, but I always thought that without any fancy window managers, applications such as Renoise could just draw directly with good performance.
I’m using JACK too, I tried removing PulseAudio for testing but it made no difference. I believe it gets suspended automatically when JACK starts in any case. I’m also forced to use the previous .32 kernel even though Maverick provides .35, due to a hard system lock that I get after an Xrun if the .35 kernel is used.
I yearn for the day when Linux audio doesn’t fail.
Also I think unbuntu studio 7 was the last version which had proper realtime audio support. After that they did something to linux kernel and it has never worked properly again…
This problem is NOT localized to renoise but the entire linux audio production got the hit.
It’s not about the “impact on performance” but I think the issue is with gnome windowmanager using some realtime tricks to get better responsiveness for the windows it manages. This unfortunately conflicts with the low latency audio software.
The -rt kernel doesn’t help the issue. The thing they broke in the kernel is somewhere else which the RT patch can’t fix. Only thing you can do is pray and hope the kernel developers will see the light in the future.
I recently started using Crunchbang! linux. The latest release is based on Debian, not Ubuntu, and uses Openbox front end. So its a very resource-friendly system, and I’m having a ball with it. I’ve configured all my audio to go through JACK without having to use pulseaudio (which isn’t installed by default).
