Demo core dump on Ubuntu

[Winawer]

Clean install of opencv 2.4.9 on an Ubuntu 14.04 VM, bgslibrary builds fine but the demos immediately dump core.

winawer@ubuntu:~/Downloads/bgslibrary/build$ ./bgs_demo vtest2.avi
Using OpenCV 2.4.9
Openning: vtest2.avi
FrameDifferenceBGS()
OpenCV Error: Null pointer (Invalid pointer to file storage) in cvWriteInt, file    /home/winawer/Downloads/opencv-2.4.9/modules/core/src/persistence.cpp, line 2964
terminate called after throwing an instance of 'cv::Exception'
what():  /home/winawer/Downloads/opencv-2.4.9/modules/core/src/persistence.cpp:2964: error: (-27) Invalid pointer to file storage in function cvWriteInt

and

winawer@ubuntu:~/Downloads/bgslibrary/build$ ./bgs -uf=true -fn vtest2.avi
-----------------------------------------
Background Subtraction Library v1.9.1     
http://code.google.com/p/bgslibrary       
by:                                       
Andrews Sobral (andrewssobral@gmail.com)  
-----------------------------------------
Using OpenCV version 2.4.9
VideoAnalysis()
VideoCapture()
FrameProcessor()
OpenCV Error: Null pointer (Invalid pointer to file storage) in cvWriteString, file    /home/winawer/Downloads/opencv-2.4.9/modules/core/src/persistence.cpp, line 2980
std::exception:/home/winawer/Downloads/opencv- 2.4.9/modules/core/src/persistence.cpp:2980: error: (-27) Invalid pointer to file storage in  function cvWriteString

Repeated the test with other videos, including the one in the repo (video.avi). Same thing. OpenCV demos and helloworlds run fine, so I don't think it's an OpenCV issue. Compiled the code in the README as well, got the same problem:

winawer@ubuntu:~/Downloads/bgslibrary/build$ ./test
HIGHGUI ERROR: V4L/V4L2: VIDIOC_S_CROP
FrameDifferenceBGS()
select timeout
 OpenCV Error: Null pointer (Invalid pointer to file storage) in cvWriteInt, file /home/winawer/Downloads/opencv-2.4.9/modules/core/src/persistence.cpp, line 2964
 terminate called after throwing an instance of 'cv::Exception'
 what():  /home/winawer/Downloads/opencv-2.4.9/modules/core/src/persistence.cpp:2964: error: (-27) Invalid pointer to file storage in function cvWriteInt
 Aborted (core dumped)

[Winawer]

Bah, never mind, I'm clearly doing something wrong. The batch files run correctly, though I can't yet see what the difference is.

[Answeror]

You need config folder in your current working directory.

[cmaria4]

I have the same problem: OpenCV Error: Null Pointer (Invalid pointer to file storage) in cvWriteString file, C:\builds\2_4_PackSlave-win32-vc12-shared\opencv\modules\core\src\persistence.cpp, line 2980 How can I fix it? The .exe file does not run!

[andrewssobral]

Hi @cmaria4 , you need to create a config folder in your current working directory (as @Answeror says)

[mraxilus]

Shouldn't that be added to the readme then? I had the same problem.