Please post a backtrace including KMix debuginfo and report it here.

Distribution specific installation guides for installing debuginfo packages can be found on http://techbase.kde.org/Development/Tutorials/Debugging/How_to_create_useful_crash_reports

Especially important is that you do not forget to install the debuginfo packages for the KMix application.

As expained in my post, I attempted to download the debug tools when using the automated crash report - but the software told me that they are unavailable for kmix.

Apparently:

The packages containing debug information for the following application and libraries are missing:

/usr/bin/kmix
<this is installed in this location>
/usr/lib/x86_64-linux-gnu/libpulsecommon-1.1.so
<libpulsecommon* does not exist in the kubuntu repositories
/usr/lib/kde4/libkdeinit/libkdeinit4_kmix.so
<libkdeinit4* does not exist in the kubuntu repositories
/usr/lib/x86_64-linux-gnu/libpulse.so.0
<I have just installed libpulsedsp-dbg and libpulse0-dbg>

/usr/lib/x86_64-linux-gnu/libpulse-mainloop-glib.so.0

This is the most recent backtrace:

Application: KMix (kmix), signal: Segmentation fault
Using host libthread_db library "/lib/x86_64-linux-gnu/libthread_db.so.1".
[Current thread is 1 (Thread 0x7fa08632d780 (LWP 4030))]

Thread 3 (Thread 0x7fa0662ed700 (LWP 4032)):
#0  0x00007fa08296db75 in postEventSourcePrepare (s=0x7fa0600012d0, timeout=0x7fa0662ecc6c) at kernel/qeventdispatcher_glib.cpp:255
#1  0x00007fa07b9f371e in g_main_context_prepare () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
#2  0x00007fa07b9f3f1b in ?? () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
#3  0x00007fa07b9f4124 in g_main_context_iteration () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
#4  0x00007fa08296e426 in QEventDispatcherGlib::processEvents (this=0x7fa0600008c0, flags=...) at kernel/qeventdispatcher_glib.cpp:426
#5  0x00007fa08293dc82 in QEventLoop::processEvents (this=<optimized out>, flags=...) at kernel/qeventloop.cpp:149
#6  0x00007fa08293ded7 in QEventLoop::exec (this=0x7fa0662ecdd0, flags=...) at kernel/qeventloop.cpp:204
#7  0x00007fa08283cfa7 in QThread::exec (this=<optimized out>) at thread/qthread.cpp:501
#8  0x00007fa08291d9ff in QInotifyFileSystemWatcherEngine::run (this=0x2056e30) at io/qfilesystemwatcher_inotify.cpp:248
#9  0x00007fa08283ffcb in QThreadPrivate::start (arg=0x2056e30) at thread/qthread_unix.cpp:298
#10 0x00007fa07c55ae9a in start_thread (arg=0x7fa0662ed700) at pthread_create.c:308
#11 0x00007fa085bf34bd in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:112
#12 0x0000000000000000 in ?? ()

Thread 2 (Thread 0x7fa0658e0700 (LWP 4033)):
#0  0x00007fffe35ff8f7 in ?? ()
#1  0x00007fa07c34f15d in __GI_clock_gettime (clock_id=<optimized out>, tp=<optimized out>) at ../sysdeps/unix/clock_gettime.c:116
#2  0x00007fa082896bb4 in do_gettime (frac=0x7fa0658dfb98, sec=0x7fa0658dfb90) at tools/qelapsedtimer_unix.cpp:123
#3  qt_gettime () at tools/qelapsedtimer_unix.cpp:140
#4  0x00007fa08296eb8d in QTimerInfoList::updateCurrentTime (this=0x7fa054002660) at kernel/qeventdispatcher_unix.cpp:343
#5  0x00007fa08296eec3 in QTimerInfoList::timerWait (this=0x7fa054002660, tm=...) at kernel/qeventdispatcher_unix.cpp:450
#6  0x00007fa08296d97c in timerSourcePrepareHelper (src=<optimized out>, timeout=0x7fa0658dfc6c) at kernel/qeventdispatcher_glib.cpp:136
#7  0x00007fa08296da25 in timerSourcePrepare (source=<optimized out>, timeout=<optimized out>) at kernel/qeventdispatcher_glib.cpp:169
#8  0x00007fa07b9f371e in g_main_context_prepare () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
#9  0x00007fa07b9f3f1b in ?? () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
#10 0x00007fa07b9f4124 in g_main_context_iteration () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
#11 0x00007fa08296e426 in QEventDispatcherGlib::processEvents (this=0x7fa0540008c0, flags=...) at kernel/qeventdispatcher_glib.cpp:426
#12 0x00007fa08293dc82 in QEventLoop::processEvents (this=<optimized out>, flags=...) at kernel/qeventloop.cpp:149
#13 0x00007fa08293ded7 in QEventLoop::exec (this=0x7fa0658dfdd0, flags=...) at kernel/qeventloop.cpp:204
#14 0x00007fa08283cfa7 in QThread::exec (this=<optimized out>) at thread/qthread.cpp:501
#15 0x00007fa08291d9ff in QInotifyFileSystemWatcherEngine::run (this=0x1eaea60) at io/qfilesystemwatcher_inotify.cpp:248
#16 0x00007fa08283ffcb in QThreadPrivate::start (arg=0x1eaea60) at thread/qthread_unix.cpp:298
#17 0x00007fa07c55ae9a in start_thread (arg=0x7fa0658e0700) at pthread_create.c:308
#18 0x00007fa085bf34bd in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:112
#19 0x0000000000000000 in ?? ()

Thread 1 (Thread 0x7fa08632d780 (LWP 4030)):
[KCrash Handler]
#6  0x0000000000000000 in ?? ()
#7  0x00007fa085f13e26 in ?? () from /usr/lib/kde4/libkdeinit/libkdeinit4_kmix.so
#8  0x00007fa085f0f64b in ?? () from /usr/lib/kde4/libkdeinit/libkdeinit4_kmix.so
#9  0x00007fa082953281 in QMetaObject::activate (sender=0x206eba0, m=<optimized out>, local_signal_index=<optimized out>, argv=0x0) at kernel/qobject.cpp:3547
#10 0x00007fa082953281 in QMetaObject::activate (sender=0x2070690, m=<optimized out>, local_signal_index=<optimized out>, argv=0x0) at kernel/qobject.cpp:3547
#11 0x00007fa085ee8b0c in ?? () from /usr/lib/kde4/libkdeinit/libkdeinit4_kmix.so
#12 0x00007fa085ef8df5 in ?? () from /usr/lib/kde4/libkdeinit/libkdeinit4_kmix.so
#13 0x00007fa0842d0944 in context_get_sink_info_callback (pd=<optimized out>, command=<optimized out>, tag=<optimized out>, t=0x1ee1140, userdata=0x20e3e20) at pulse/introspect.c:280
#14 0x00007fa07bf12693 in run_action (pd=0x20e4590, r=0x20e2540, command=2, ts=0x1ee1140) at pulsecore/pdispatch.c:279
#15 0x00007fa07bf12a03 in pa_pdispatch_run (pd=0x20e4590, packet=<optimized out>, creds=0x21294a0, userdata=0x20c00e0) at pulsecore/pdispatch.c:331
#16 0x00007fa0842c6bdd in pstream_packet_callback (p=<optimized out>, packet=0x204b0d0, creds=0x21294a0, userdata=0x20c00e0) at pulse/context.c:335
#17 0x00007fa07bf172a9 in do_read (p=0x2129350) at pulsecore/pstream.c:809
#18 do_something (p=0x2129350) at pulsecore/pstream.c:177
#19 0x00007fa0840b4ab3 in ?? () from /usr/lib/x86_64-linux-gnu/libpulse-mainloop-glib.so.0
#20 0x00007fa07b9f3c9a in g_main_context_dispatch () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
#21 0x00007fa07b9f4060 in ?? () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
#22 0x00007fa07b9f4124 in g_main_context_iteration () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
#23 0x00007fa08296e3bf in QEventDispatcherGlib::processEvents (this=0x1cbead0, flags=...) at kernel/qeventdispatcher_glib.cpp:424
#24 0x00007fa083658d5e in QGuiEventDispatcherGlib::processEvents (this=<optimized out>, flags=...) at kernel/qguieventdispatcher_glib.cpp:204
#25 0x00007fa08293dc82 in QEventLoop::processEvents (this=<optimized out>, flags=...) at kernel/qeventloop.cpp:149
#26 0x00007fa08293ded7 in QEventLoop::exec (this=0x7fffe351d5d0, flags=...) at kernel/qeventloop.cpp:204
#27 0x00007fa082942f67 in QCoreApplication::exec () at kernel/qcoreapplication.cpp:1148
#28 0x00007fa085f003e2 in kdemain () from /usr/lib/kde4/libkdeinit/libkdeinit4_kmix.so
#29 0x00007fa085b2276d in __libc_start_main (main=0x400630, argc=5, ubp_av=0x7fffe351db58, init=<optimized out>, fini=<optimized out>, rtld_fini=<optimized out>, stack_end=0x7fffe351db48) at libc-start.c:226
#30 0x0000000000400661 in _start ()

Can't do anything then, unfortunately. Please try again with KDE 4.8.3. I fixed KMix crashes there, so just try and report back.

(In reply to comment #3)
> Can't do anything then, unfortunately. Please try again with KDE 4.8.3. I
> fixed KMix crashes there, so just try and report back.

Regrettably I am already running 4.8.3
It's hardly the end of the world, it's just something that happens every time.

For diagnostic purposes I have also installed DosBox on my laptop, which also runs KDE 4.8.3, also on the 64-bit platform.  This also crashes Kmix when dosbox is closed.

To replicate this fault properly:

My dosbox starts automatically with the machine.  If yours does not, close kmix, then open DosBox then re-open kmix.  Kmix then has a dosbox volume slider.

Now close dosbox - either by issuing an "exit" command, or by using the close icon, or by using Alt&F4.  Kmix will now crash and offer you an opportunity to report the fault.

The ONLY happens when there is a volume slider in kmix for dosbox and dosbox is then closed.

Scratch my last comment, I have just checked my laptop and it was running 4.8.2 - I have now upgraded, it is running on 4.8.3, dosbox does not crash kmix - regardless of whether the volume slider is present for dosbox or not.  

I don't know why it does this on my main desktop machine but clearly it is isolated to it, not a general kde bug.  Please close this ticket.

Dear Bug Submitter,

This bug has been in NEEDSINFO status with no change for at least 15 days. Please provide the requested information as soon as possible and set the bug status as REPORTED. Due to regular bug tracker maintenance, if the bug is still in NEEDSINFO status with no change in 30 days, the bug will be closed as RESOLVED > WORKSFORME due to lack of needed information.

For more information about our bug triaging procedures please read the wiki located here: https://community.kde.org/Guidelines_and_HOWTOs/Bug_triaging

If you have already provided the requested information, please set the bug status as REPORTED so that the KDE team knows that the bug is ready to be confirmed.

Thank you for helping us make KDE software even better for everyone!

Dear Bug Submitter,

This bug has been in NEEDSINFO status with no change for at least 30 days. The bug is now closed as RESOLVED > WORKSFORME due to lack of needed information.

For more information about our bug triaging procedures please read the wiki located here: https://community.kde.org/Guidelines_and_HOWTOs/Bug_triaging

Thank you for helping us make KDE software even better for everyone!