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Lately I noticed that something seems to be blocking various audio controls - mixer mostly. I can't access mixer window from taskbar, my keyboard volume knob doesn't work, mute too.

But - all the generated events are there, because when the problem goes away (usually in the range of 10-30 seconds), all the events that I generated (volume up/down, mute) are applied.

Any idea on what could that be, or how to debug it?

Straced kmix startup. And it looks like it was waitinf for some information from dbus - i see it sent and received some messages to fd=3 (which is earlier connected to /tmp/dbus-something), and then it waits 21 seconds!, and then it gets new message from dbus, message looks like:

27888 15:16:43.485816 recvmsg(3, {msg_name(0)=NULL, msg_iov(1)=[{"l\2\1\1\302\v\0\0,\0\0\0.\0\0\0\6\1s\0\6\0\0\0:1.102\0\0\5\1u\0\t\0\0\0\10\1g\0\1s\0\0\7\1s\0\5\0\0\0:1.44\0\0\0\275\v\0\0<!DOCTYPE node PUBLIC \"-//freedesktop//DTD D-BUS Object Introspection 1.0//EN\"\n\"\">\n<node>\n  <interface name=\"org.kde.KApplication\">\n    <method name=\"updateUserTimestamp\">\n      <arg name=\"time\" type=\"i\" direction=\"in\"/>\n    </method>\n    <method name=\"updateUserTimestamp\">\n    </method>\n    <method name=\"reparseConfiguration\">\n    </method>\n    <method name=\"quit\">\n    </method>\n  </interface>\n  <interface name=\"com.trolltech.Qt.QApplication\">\n    <property name=\"cursorFlashTime\" type=\"i\" access=\"readwrite\"/>\n    <property name=\"doubleClickInterval\" type=\"i\" access=\"readwrite\"/>\n    <property name=\"keyboardInputInterval\" type=\"i\" access=\"readwrite\"/>\n    <property name=\"wheelScrollLines\" type=\"i\" access=\"readwrite\"/>\n    <property name=\"globalStrut\" type=\"(ii)\" access=\"readwrite\">\n      <annotation name=\"com.trolltech.QtDBus.QtTypeName\" value=\"QSize\"/>\n    </property>\n    <property name=\"startDragTime\" type=\"i\" access=\"readwrite\"/>\n    <property name=\"startDragDistance\" type=\"i\" access=\"readwrite\"/>\n    <property name=\"quitOnLastWindowClosed\" type=\"b\" access=\"readwrite\"/>\n    <property name=\"styleSheet\" type=\"s\" access=\"readwrite\"/>\n    <property name=\"autoSipEnabled\" type=\"b\" access=\"readwrite\"/>\n  </interface>\n  <interface name=\"com.trolltech.Qt.QCoreApplication\">\n    <property name=\"applicationName\" type=\"s\" access=\"readwrite\"/>\n    <property name=\"applicationVersion\" type=\"s\" access=\"readwrite\"/>\n    <property name=\"organizationName\" type=\"s\" access=\"readwrite\"/>\n    <property name=\"organizationDomain\" type=\"s\" access=\"readwrite\"/>\n  </interface>\n  <interface name=\"org.kde.KUniqueApplication\">\n    <method name=\"newInstance\">\n      <arg type=\"i\" direction=\"out\"/>\n      <arg name=\"asn_id\" type=\"ay\" direction=\"in\"/>\n      <arg name=\"args\" type=\"ay\" direction=\"in\"/>\n    </method>\n    <method name=\"newInstance\">\n      <arg type=\"i\" direction=\"out\"/>\n      <arg name=\"asn_id\" type=\"ay\" dir", 2048}], msg_controllen=0, msg_flags=MSG_CMSG_CLOEXEC}, MSG_CMSG_CLOEXEC) = 2048 <0.000008>

It contains string "introspection" - no idea what it is about, but perhaps it could be related?

I am very willing to do additional tests/straces/whatever to solve the problem, so if you have any ideas - please speak up.

share|improve this question
What Linux Distro and Audio Card do you have? – Arctor Mar 24 '11 at 13:57
It's kubuntu maverick. as for sound card - lspci shows: 00:1b.0 Audio device: Intel Corporation 82801JI (ICH10 Family) HD Audio Controller – user7385 Mar 24 '11 at 16:48

Not an answer but lets me better format my suggestions than commenting.

Get your hands on some .wav files not sure what aplay supports natively but no point in trying to get it to support something like mp3 if it doesn't already.

Try to eliminate as my conflicting processes as possible by typing this at the command prompt.

  1. sudo init 3 ...this should drop you to the command-line only you can eliminate even more by entering single user mode sudo init 1 but it might eliminate to much not sure.

  2. Log in if not already and type alsamixer if its not found try sudo apt-get install alsa-utils first. Alsamixer will allow you to manipulate the volume with your arrow keys in the interface that it launches.

  3. Hit ctrl+alt+f1 this should bring you to a fresh command prompt login again.

  4. Execute aplay /path/to/sound.wav the file should start playing.

  5. Hit ctrl+alt+f7 to get back to the alsamixer if it is a blank prompt flip through them to find which one it is ctrl+alt+f2... etc etc.

  6. Start adjusting the volume to see if there is a delay.

sudo init 5 to get back your GUI

share|improve this answer
alsamixer works fine even in konsole/kde. i suspect the dbus, but have no idea what it could be. – user7385 Mar 24 '11 at 17:58
If the audio system works fine with alsamixer. Installing the proper drivers for your keyboard should fix that issue. Now we need to figure out what is wrong with the GUI audio mixer I have not used kubuntu so I dont know the name of it but if you could right click on the mixer and click about if it exists.. you can find out what the name of it is you could try uninstalling it and its related files and reinstalling it to see if something was broken.... – Arctor Mar 24 '11 at 19:45
after doing a search looks like it might be kmix.. an alternative to this is kalsamixer – Arctor Mar 24 '11 at 19:48
screensaver is also slow to finish. kmix is just one of applications that's easy to test. as for keyboard - keyboard works just fine. and the slowdown happens also when I click on icons (like the icon for kmix), or when closing screensaver. – user7385 Mar 25 '11 at 8:12
gahhhh why are you posting that now lol – Arctor Mar 25 '11 at 10:58

You can get rid of kmix entirely and use shorcuts instead:

amixer -c 0 set Master 3- unmute
amixer -c 0 set Master 3+ unmute
amixer -c 0 set PCM 3- unmute
amixer -c 0 set PCM 3+ unmute

The first two will raise/lower the Master volume, the last two will do the same for PCM channel.

I have them mapped to Win+Up, Win-Down, and Ctr+Win+Up, Ctr+Win+Down accordingly. No more mousing around.

share|improve this answer
Well, sure, I know. I can also bind it to keyboard shortcuts. But I'm much more interested in source of the problem, and proper fix of it, rather than workaround. – user7385 Mar 28 '11 at 22:04

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