Crash on startup: Cannot get capabilities.

Kdenlive crashes when installing from:
#dpkg -l | grep kdenlive
ii kdenlive 0.8.0-0ubuntu0~sunab~lucid1 a non-linear video editor
ii kdenlive-data 0.8.0-0ubuntu0~sunab~lucid1 a non-linear video editor (data files)

With output:
project monitor connected
clip monitor connected
Cannot get capabilities.KCrash: Application 'kdenlive' crashing...

More info...

A backtrace gives:
Starting program: /usr/bin/kdenlive --nocrashhandler
[Thread debugging using libthread_db enabled]
project monitor connected
clip monitor connected
Cannot get capabilities.
Program received signal SIGSEGV, Segmentation fault.
0x002e0b20 in QString::fromLatin1_helper(char const*, int) () from /usr/lib/
(gdb) bt
#0 0x002e0b20 in QString::fromLatin1_helper(char const*, int) () from /usr/lib/
#1 0x002e68f4 in QString::fromAscii_helper(char const*, int) () from /usr/lib/
#2 0x083b95a9 in ?? ()
#3 0x082f131f in ?? ()
#4 0x082f29dd in ?? ()
#5 0x0809eaa1 in _start ()

A "bad" workaround:
Remove /dev/video0 and /dev/video1. Then kdenlive does not crash anymore, but bad because it disables all my v4l devices.

Further information:
#cat /etc/lsb-release

My thoughts:
I suspect my system has no (full) support for v4l2. The ioctl VIDIOC_QUERYCAP is missing. kdenlive cannot handle that.

Looking forward to version 0.8.1 ;-)


Thanks for the detailled post, your analysis seems correct. I just made a few changes that should help fixing this issue in current svn.



Do you think you could try the current development version to confirm that the startup crash is fixed?

You can install easily with sunab's ppa:

Let me know if you find time for it, so that we can prepare a bugfix release.


I installed version: 0.8.1+svn20110606.r5673-0ubuntu0~sunab~lucid1.

It doesn't crash, but I cannot continue because of the following error (shown in the kdenlive config wizard welcome screen):

Fatal Error
MLT's SDL module not found. Please check your MLT install. Kdenlive will not work until this issue is fixed.

Maybe the debian package is missing a dependency rule?

Ps. I have libmlt4 installed:
#dpkg -l | grep libmlt4
ii libmlt4 0.7.3+git20110606.7a394eef-0ubuntu0~sunab~lucid1 multimedia framework (runtime)



Oh, yes I see the same problem on a test system... Investigating the issue.

Ok, in fact the way Kdenlive checked for MLT's installation was rather ugly and broken by a recent MLT commit. I just rewrote it to correctly identify installed modules.

So you will have to wait a few days for sunab's packages to rebuild (I don't know how frequent is the update & rebuild process). As a temporary workaround to start Kdenlive, you could try to edit the file:


And look for this:


Change it to:


and Kdenlive should start without complaining.

Ok, sunab's experimental repository was just updated to the latest Kdenlive svn version, so you can update and try again, thanks


I checked, and can confirm that kdenlive does not crash anymore. Thanks!

My webcam is not detected, but I guess, as I said before, that's due to old v4l drivers in kubuntu. I do not use my webcam, so I do not really care. I can provide you with more info if you're interested.

I now run version 0.8.1+svn20110615.r5716-0ubuntu0~sunab~lucid1

I'm having trouble saving files. Kdenlive seems to hang on the "save" button.

The terminal gives (every second or so) the following output:

"kdenlive(6153): Failed to lock file "/var/tmp/kdecache-michel/kpc/kdenlive-thumbs.lock" , last result = 1"

Edit: more info in