[PlanetCCRMA] fc13: alsa-tools, jconvolver

[Fernando Lopez-Lezcano]

On Sat, 2010-09-18 at 16:53 -0700, Jeff Sandys wrote:
> >> Date: Thu, 16 Sep 2010 11:22:27 -0700
> >> From: Fernando Lopez-Lezcano <nando at ccrma.Stanford.EDU>
> >> Subject: [PlanetCCRMA] fc13: alsa-tools, jconvolver
> >>
> >> Also... I released a version of akmod-nvidia (arghhh) in the
> >> planetcore-testing repository that appears to compile the glue module
> >> cleanly on rt kernels. Only tested _once_ in a new laptop[*], appears to
> >> work but as you already know no support is possible at all for binary
> >> drivers. I do see an rt related warning because of the nvidia driver but
> >> video appears to work anyway (don't know for how long :-).
> >>
> >> [*] while nouveau works fine and gives a nice graphical startup and a
> >> nice display after boot, the latencies it induces are really really bad.
> >> Hopefully it will evolve into better latencies...
> 
> How can you tell (scientifically) what nouveau's impact is on latency?

Nothing scientific about it. I installed fc13 on a new t510 lenovo with
discrete graphics (and I got that one because if you configure with the
Intel integrated graphics which I would have preferred then you can't
get the best resolution display, arghh) - coult not install fc12 as it
would not do the right thing and the display was blank. 

Anyway, jack was very unreliable with the integrated audio and once I
connected the RME Multiface I saw the exact same behavior. Lots of xruns
just moving the cursor from window to window. Then I remembered reading
about latency vs. nouveau and I installed the nvidia driver much to my
distaste (nouveau seemed to be working just fine other than that). The
xruns just went away and that was the only change so I presume the
problem was nouveau. 

> I'm running 16ms (3x256 at 48000) latency on my new laptop using
> nouveau with fedora 13.  This is about the same as on my old laptop
> using f12 and the nvidia akmod from rpmfusion.

Glad to hear that it is working on some other hardware. There is hope...
I run 2x128 with the RME for my realtime pieces. 

> I've seen some comments about audio latency issues with nouveau
> and akmod-nvidia, and I know that nouveau and akmod-nvidia clash.
> If nouveau is causing really bad audio latency, it should be reported.

I'll try to, but it will have to wait for a couple of weeks (trip coming
up with the usual craziness of trying to finish up things before
leaving[*]). 

> Thanks for building the akmod for nvidia, and I hope your changes get
> merged into rpmfusion.  I have been using the akmod since f10 with
> no problems.  Except I had some problems with it on f13 on my new
> laptop, so I switched to nouveau, and after I cleaned out all the
> nvidia stuff it works fine.

Good!
-- Fernando

[*] nothing's easy, on the new laptop I'm using fc13 and the version of
evolution that comes with it is not happy with all my email data - for
some reason it refuses to show the INBOX of my main account, everything
else is fine, so now I'm trying to move to thunderbird (something I've
been meaning to do for a while).