Bug 367900

Summary:	Frequent segmentation fault when splitting tracks in timeline, related to libqtcore5.so Object disconnect
Product:	[Applications] kdenlive	Reporter:	Josh Adams <josh.rubyist>
Component:	User Interface & Miscellaneous	Assignee:	Jean-Baptiste Mardelle <jb>
Status:	RESOLVED UNMAINTAINED
Severity:	crash	CC:	snd.noise, wegwerf-1-2-3
Priority:	NOR
Version:	16.08.0
Target Milestone:	---
Platform:	Arch Linux
OS:	Linux
Latest Commit:		Version Fixed In:
Sentry Crash Report:
Attachments:	This is the output of `coredumpctl info` for the process coredump from most recent crash gdb backtrace

Description Josh Adams 2016-08-27 14:56:00 UTC

Since upgrading to 16.08.0 on Arch Linux, I suffer frequent segmentation faults in one specific case.

When splitting a track in the timeline, seemingly 20-30% of the time now it will crash the application with a Segmentation Fault.  I have attached a coredump of the problem.

P.S. - lots of *other* annoying bugs were fixed in this release, so thanks very much for that!  This segfault on track splitting, though, is new and somewhat debilitating.

Reproducible: Sometimes

Steps to Reproduce:
1. Create a new project, add an mp4 file to the clips area, drag it onto the timeline, and save it.
2. Split the mp4 file.  I do this after playing it for a bit because I am editing videos (obviously) and so I watch through them.  I frequently cut out bits (coughs, etc) and occasionally cut to speed things up (ungroup the clips, add speed to the video clip, make audio the same length as the sped up video)
3. Make splits of this sort a few times (2-6?)

Actual Results:  
After doing this some number of times (never happened the first cut so far, but generally happens by the time I've cut 5 or 6 times in one session), the UI will hang up for a bit and then the window disappears.  This is because of a segmentation fault.

Expected Results:  
Clip is split and application does not segfault :)

I'm running the nvidia proprietary driver but I doubt that's remotely related based on the attached coredump.

Comment 1 Josh Adams 2016-08-27 14:56:43 UTC

Created attachment 100808 [details]
This is the output of `coredumpctl info` for the process

Comment 2 Josh Adams 2016-08-27 15:07:03 UTC

First off, coredump itself is coming, just waiting on it to upload.  Here's some additional information.

KDE Frameworks 5.25.0
Qt 5.7.0 (built against 5.7.0)
The xcb windowing system

Comment 3 Josh Adams 2016-08-27 15:12:50 UTC

Created attachment 100809 [details]
coredump from most recent crash

Comment 4 Jean-Baptiste Mardelle 2016-09-04 20:33:26 UTC

Thanks for your report. I cannot reproduce, and I am wondering if the Kdenlive package is compiled against Qt 5.6, and if that crash could be caused by you having Qt 5.7. I am absolutely not familiar with Arch packaging so maybe it's not the problem. In that case, a gdb backtrace would be easier for me if you can provide one.

Comment 5 Josh Adams 2016-09-05 05:58:37 UTC

I provided a core dump because you can attach to it with gdb trivially. I can provide a backtrace if that would be better; can you tell me what all you would need, or why the coredump isn't sufficient, for my own edification?

Comment 6 Josh Adams 2016-09-05 06:00:27 UTC

Also kdenlive about dialog specifies it was built against qt 5.7.0 and that it was running against 5.7.0 (I provided that earlier as well)

Comment 7 Jean-Baptiste Mardelle 2016-09-05 06:06:41 UTC

Yes, I know coredump is supposed to be more useful, however when I tried using yours, it compained I was not using the same kdenlive version and was unable to produce any symbol...

My laptop is on Qt 5.6, so maybe that's related.. I do not have a sufficient knowledge of core dumps, and usually a simple crash backtrace provides enough hints about where the crash is triggered.

Comment 8 Josh Adams 2016-09-06 03:35:57 UTC

Created attachment 100946 [details]
gdb backtrace

Comment 9 farid 2016-10-05 04:02:17 UTC

I think this could be somehow related to this:
https://bugs.kde.org/show_bug.cgi?id=368302

Could you please test the described steps with the "Split audio and video automatically" button enabled in the buttom panel before the dragging any clip in the timeline and report back? 

Thanks for the help.

Comment 10 Josh Adams 2016-10-05 17:20:51 UTC

I always have that enabled, so my existing bug report was done in that state :)

Comment 11 Wegwerf 2017-02-05 11:00:57 UTC

Still present with current stable 16.12.1?

Comment 12 farid 2017-02-06 16:57:57 UTC

Hi Josh could you please provide some feedback?

Comment 13 Josh Adams 2017-02-06 17:15:15 UTC

Can't provide any more details - I was forced to move to the mac and use screenflow because the crashes were too frequent.

Unrelated: If I can get my company (dailydrip.com) nice and successful, I have every intention of contributing money to ensure an open source competitor is better in every way than the proprietary alternatives I'm having to use presently.

Comment 14 farid 2017-02-06 17:21:27 UTC

Thanks Josh, Do keep an eye on Kdenlive since this year we are finishing a refactoring which will introduce many new features and stability. Good luck!

Comment 15 Wegwerf 2017-02-06 17:33:51 UTC

There was actually a fix to MLT and a workaround in Kdenlive related to crashes caused by cutting clips just yesterday, related to some pointer handling problem. That may have improved the situation.