Frequent crashes .. no debugging??

[opentrack]

Frequent crashes .. no debugging??

[sthalik]

What OS is it? Only OSX is known to have severe problems at the moment.

[chsims1]

Sorrry, used to abbreviating arch-linux to arch....so OS is linux.

Compiles and runs fine. Choosing point tracker and start works ok .. starts tracking. If I try and stop this then it hangs ... just sits there apparently doing nothing.

[sthalik]

It's likely an issue with the build environment. It worked for me with no problems for a long while. Almost all of the codebase is portable, and doesn't use any platform-specific bits.

Could be linking against 2 different versions of one library, or anything... Unless you submit a backtrace, it's impossible to solve it.

[chsims1]

Thanks for the comment ... not sure that I will get round to that.

[sthalik]

What's your Qt graphics system anyway? Use "raster" and not "native". Run like this:

./opentrack -graphicssystem raster

With native, there are nasty Linux-only bugs. Hope this helps!

[chsims1]

Nope, made no difference.

I have made an attempt to use gdb to get a backtrace ... what is the best way to get it to you (15kB)?

Try here: https://gist.github.com/chsims1/8396314

[sthalik]

Looks like camera can't be properly opened, and blocks during frame retrieval. Hence, attempt to stop the tracking process, as shown in the backtrace, locks up the app.

This isn't something that can be fixed inside opentrack.

See how threads 4, 5 and 1 interact.

[chsims1]

BTW, the camera (PS3 eye) works fine in FTNoIR under Windows. Is this a linux peculiarity?

[sthalik]

That's a kernel bug. Try updating to 3.12 or later.

[chsims1]

uname -r
3.12.6-1-ARCH

[sthalik]

You could be missing ehci/xhci in the kernel, while having the camera connected to an USB3 port. It could be an old version of opencv, or old version of libv4l2.

Does "qv4l2" show frames from the camera, or does it lock up like opentrack?

[chsims1]

qv4l2 works fine.

local/opencv 2.4.8-1
Open Source Computer Vision Library

[sthalik]

Does opentrack ever show a frame in the software's video feed, or is it consistently blank?

Does qv4l2 work at the same framerate as opentrack, or only at 30 hz? Try switching the camera port to a different USB controller, i.e. USB2 instead of possibly USB3.

[chsims1]

opentrack works fine ie.shows video/points. It hangs when I attempt to stop the video/tracking.

qvl2 works at a variety of framerates.

hmm, need to find which are the usb2 ports to answer that one.

[sthalik]

In ftnoir_tracker_pt.h:68, change "int commands" to "volatile int commands".

In ftnoir_tracker_pt.cpp:48, comment out the "QMutexLocker lock(&mutex);" line.

It could indeed be a Linux-specific issue.

Does it help?

If we can't get it working within 20 minutes, will answer further responses after 17:00 CET. Already late :)

[chsims1]

Just plugged webcam directly into usb port rather than hub. It now crashes with the following message:

OpenCV Error: Assertion failed (count >= 4) in cvFindHomography, file /build/opencv/src/opencv-2.4.8/modules/calib3d/src/fundam.cpp, line 235
terminate called after throwing an instance of 'cv::Exception'
what(): /build/opencv/src/opencv-2.4.8/modules/calib3d/src/fundam.cpp:235: error: (-215) count >= 4 in function cvFindHomography

Aborted (core dumped)

[sthalik]

% git pull

The version of opencv you're using is incompatible with the change, that's since been reverted.

I'll fix the mutex starvation anyway. Done. FWIW, it's only PT that has this problem.

If there's any ambiguity, it's opentrack that needs to be pulled, opencv is fine.

[chsims1]

Ok that solved that problem. Still hanging on attempting to stop video though

[sthalik]

Can you verify that aforementioned lines in .cpp and .h are commented out qmutexlocker and "volatile int commands", respectively?

[chsims1]

Yep, lines confirmed.

[sthalik]

It's actually tracker thread in tracker.cpp that blocks. Sorry for the misdiagnosis.

What's the GNU CC version? Seems like an obvious bug given volatile status of bool Tracker::should_stop.

Don't get me wrong though, will work around the issue, but only after getting back home. Too involved to do now.

If you want to fix it on your own, make QMutex in tracker.h public, then move the QMutexLocker line in tracker.cpp to the top, right after "forever {", but before "if (should_stop)". Then in facetracknoir.cpp:stopTracker, add "QMutexLocker(&tracker->mtx);" on line 421, just after "if (tracker) {". The changes are quite involved and not a proper fix, but can't think of anything simpler right now, and have to leave.

[chsims1]

Thanks for your efforts. I will look later .... things to do now. Cheers!

local/gcc-libs-multilib 4.8.2-7

Since your change to git earlier, hanging behaviour has changed .... no longer hangs permanently. Instead hangs for a minute or so, before reporting that "Tracker:: Thread stopping"

What does "HEAD-HASH-NOT FOUND" in window title bar mean? (I didn't notice this previously)

[sthalik]

What's your GCC version? Will you be here today to test patch?

[sthalik]

Titlebar version is taken from Git and it seems like the repo's either malformed or there's no Git installed on the system.

Try this:

https://gist.github.com/sthalik/8406027

[sthalik]

Should be fixed now. Can you confirm?

[chsims1]

Hi, yes it works fine now ,,,, tyvm. Impressive speed of resolution. I'll go and have a play now.