[LAD] [64studio-users] MIDI jitter

[Ralf Mardorf]

There's still an issue with the latest Kernel and my NVIDIA, but on
Tuesday I should be able to compare my USB's to my PCI card's MIDI. I
guess @jackuser - nice -10 for rt has got no impact.
I'm thinking to run the ALSA MIDI latency test without and with hrtimer
(hpet) and without and with glxgears running.


On Sat, 2010-07-03 at 09:12 -0700, Niels Mayer wrote:
> 2010/7/3 Ralf Mardorf <ralf.mardorf at alice-dsl.net>:
> > On Fri, 2010-07-02 at 14:51 -0700, Niels Mayer wrote:
> >> sudo alsa-midi-latency-test -w 20 -r -R -i 36:0 -o 36:0
> >
> > Perhaps better without sudo.
> 
> I was just following Paul Davis' lead (*).
> 
> For me, there's probably no need for this, as my user 'npm' has
> membership in group jackuser spec'd in /etc/security/limits.conf :
> 
> > ## Automatically appended by the Planet CCRMA jack-audio-connection-kit
> > ## NPM changed '*' to @jackuser to limit priority escalation to jackd.
> > @jackuser - rtprio 99
> > @jackuser - memlock 4194304
> > @jackuser - nice -10
> 
> And /etc/group has entries like:
> 
> > jackuser:x:476:npm
> > rtkit:x:470:npm
> 
> Running as root sidesteps the need for such setup, as well as any
> permissions issues on the devices under test. From what I can tell,
> the only privileged access in the test program is indicated by the
> following output from 'alsa-midi-latency-test':
> 
> > set_realtime_priority(SCHED_FIFO, 99).. done.
> 
> .............................
> (*):
> On Fri, Jul 2, 2010 at 4:50 AM, Paul Davis <paul at linuxaudiosystems.com> wrote:
> > just for comparison, here are the results for an RME Digiface:
> > sudo /usr/bin/alsa-midi-latency-test -w -r -R -i 20:0 -o 20:0
> > ...
> >  best latency was 0.00 ms
> >  worst latency was 1.00 ms, which is great.
> 
> Better if Paul re-ran the test with "-w 20" argument so his fancypants
> RME doesn't end up unfairly claiming the 0ms latency title :-) ...
> 
> Who will claim the low-latency, low-jitter title in this epic
> battle-of-the-geek:
> VLSI-implemented midi on the VT1712 or RME's custom FPGA programming??
> [[ http://old.nabble.com/Is-RME-HDSPe-AES-supported-by-alsa--td28460997.html
> ]].
> 
> Note that RME's FPGA implemented MIDI and mixer lacks an important
> feature we get on cheap vt1712 VLSI implementations:
> MIDI control over the built-in digital mixer via envy24control:
> http://alsa-tools.sourcearchive.com/documentation/1.0.22-1/midi_8c-source.html
> (yes there's a built-in midi-controllable, 20 channel, 36-bit digital
> mixer hidden in that cheap ebay vt1712 --
> http://www.via.com.tw/en/products/audio/controllers/envy24/ ).
> 
> Digital mixing is an important feature of RME's TotalMix :
> http://www.rme-audio.de/en_support_techinfo.php?page=content/support/en_support_techinfo_hdsp_totalmix_hardware
> But MIDI control of that mixer seems to be lacking in alsa's hdspmixer
> and RME's implementation:
> http://www.rme-audio.de/forum/viewtopic.php?id=6105
> 
> -- Niels
> http://nielsmayer.com
> 
> PS: worlds' cheapest digital mixing console, take old/slow computer,
> add linux and these:
> http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=230491593275
> http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=260501295877

-- 
"Suse 11.2 - Proprietärer NVIDIA-Treiber
Beitrag von stachelmaus » 3. Jul 2010, 12:48 

Hi :)

für einen selbst gebauten Kernel 2.6.31.6-rt19 x86_64 habe ich den
proprietären NVIDIA Treiber installiert, für den neueren selbst gebauten
Kernel 2.6.33.5-rt23 x86_64 versuche ich nun ausschließlich das Modul zu
bauen, doch es funktionierte bisher nicht.

Der wesentliche Auszug aus /var/log/nvidia-installer.log ist
wahrscheinlich
"[...] test -e include/generated/autoconf.h -a -e
include/config/auto.conf || ( \
echo; \
echo " ERROR: Kernel configuration is invalid."; \
echo " include/generated/autoconf.h or include/config/auto.conf are
missing.";\
echo " Run 'make oldconfig && make prepare' on kernel src to fix
it.[...]".

Das ausführen von make oldconfig && make prepare hat nichts gebracht,
bzw. existieren die Dateien include/generated/autoconf.h und
include/config/auto.conf im Kernel src samt Inhalten.

Wozu es auch immer gut sein mag, den Kernel 2.6.31.6-rt19 gebootet habe
ich es u.a. mit sh ./NVIDIA*.run -a --no-questions -K
--kernel-name=2.6.33.5-rt23 und den Kernel 2.6.33.5-rt23 gebootet u.a.
mit sh ./NVIDIA*.run -a -K versucht.

Der natürlich nicht aktualisierte Installer für eine GeForce 7200 GS ist
NVIDIA-Linux-x86_64-195.36.15-pkg2.run.

Grüße

Ralf" (http://www.linux-club.de/viewtopic.php?f=48&t=110034)