To decrease MIDI jitter send to external equipment I need HR timer as
source for the sequencer.
It's not needed for MIDI internal Linux or for audio.
There is something strange.
Sometimes I get a bad message:
"This system has no accessible HPET device (Device or resource busy)"
E.g. if I try to use the attached script, everything is fine, if I run
jackd -Rch -dalsa -dhw:0 -r96000 -p512 -n2 -Xseq & sleep $time
qtractor $song_path$song_name$song_version & sleep $time
qjackctl & sleep $time
and nothing else, there's no bad message.
If I run qjackctl before I run qtractor, there will be a bad message.
If I run any of the other programs, in any order, there will be a bad
message.
If I keep away the -c h option for jackd, I can run all applications in
any order and there's no bad message. Doing this, I didn't check if HR
timer is fine as sequencer timer source, but I'm sure that HR timer is
fine with Qtractor only, when using the -c h option for jackd, because
then the jitter is decreasing significantly, I once made a test.
Is this something I should post at LAD?
#!/bin/sh
# sh start-session
song_path=""
song_name=""
song_version=""
song_date="Dec/27/2009"
time=1
hpet_max_user_freq=64
song_info="\n
######################################################################\n
# Project: $song_path$song_name$song_version\n
# $song_date Ralf Mardorf\n
# ralf.mardorf at alice-dsl dot net\n
#\n
# License for all artwork in the folder /$song_name:\n
# Creative Commons\n
# by-nc-sa = Attribution-NonCommercial- ShareAlike\n
# http://creativecommons.org/licenses/by-nc-sa/3.0/\n
# Namensnennung-NichtKommerziell-Weitergabe unter gleichen Bedingungen\n
# http://creativecommons.org/licenses/by-nc-sa/3.0/de/\n
######################################################################\n"
if [ $USER = "root" ] ; then
echo "\nOnly a user is allowed to run this script :)\n"
else
############################################################################################
sudo chgrp audio /dev/hpet
echo "\n/etc/sysctl.conf"
echo -n "dev.hpet.max-user-freq = "
cat /etc/sysctl.conf | grep dev.hpet.max-user-freq=
echo "\n"
echo -n "/proc/sys/dev/hpet/max-user-freq = "
cat /proc/sys/dev/hpet/max-user-freq
echo "\nMaking sure that the value is set to "$hpet_max_user_freq
sudo sysctl -w dev.hpet.max-user-freq=$hpet_max_user_freq
sudo modprobe snd-hrtimer
echo
echo -n "/proc/sys/dev/hpet/max-user-freq = "
cat /proc/sys/dev/hpet/max-user-freq
echo "\nSetting up CPU frequency scaling for 64 Studio."
echo "On Suse as user run the alias \"cpu-p\" or as root run \"cpufreq-set
-gperformance\"."
sudo cpufreq-selector -g performance
echo
############################################################################################
echo "\nRestoring session :)"
echo $song_info
#echo "jackd -Rch -dalsa -dhw:0 -r96000 -p512 -n2 -Xseq"
#jackd -Rch -dalsa -dhw:0 -r96000 -p512 -n2 -Xseq & sleep $time
echo "jackd -Rdalsa -dhw:0 -r96000 -p512 -n2 -Xseq"
jackd -Rdalsa -dhw:0 -r96000 -p512 -n2 -Xseq & sleep $time
#qtractor $song_path$song_name$song_version & sleep $time
qjackctl & sleep $time
a2jmidid & sleep $time
patchage & sleep $time
phasex & sleep $time
Jc_Gui & sleep $time
qtractor $song_path$song_name$song_version
fi
exit 0
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