Raspberry pi issue with webcam.open()

[shahbaz-]

Hello, I have created a program that uses webcam-capture 0.3.10-RC4. At first it wouldn't load the libs for Bridj and OpenImaj. I put the libs for both of those in the same folder where my application jar is. I ran my program and got the following output:

pi@rpi-smd1 /media/C4E7-7422/wcngs $ sudo java -jar wcngs.jar

SLF4J: Failed to load class "org.slf4j.impl.StaticLoggerBinder".
SLF4J: Defaulting to no-operation (NOP) logger implementation
SLF4J: See http://www.slf4j.org/codes.html#StaticLoggerBinder for further details.
Java HotSpot(TM) Client VM warning: You have loaded library /media/C4E7-7422/wcngs/libbridj.so which might have disabled stack guard. The VM will try to fix the stack guard now.
It's highly recommended that you fix the library with 'execstack -c <libfile>', or link it with '-z noexecstack'.
Exception in thread "main" java.lang.reflect.InvocationTargetException
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:606)
    at org.eclipse.jdt.internal.jarinjarloader.JarRsrcLoader.main(JarRsrcLoader.java:58)
Caused by: com.github.sarxos.webcam.WebcamException: Cannot execute task
    at com.github.sarxos.webcam.WebcamProcessor$AtomicProcessor.process(WebcamProcessor.java:57)
    at com.github.sarxos.webcam.WebcamProcessor.process(WebcamProcessor.java:122)
    at com.github.sarxos.webcam.WebcamTask.process(WebcamTask.java:38)
    at com.github.sarxos.webcam.ds.cgt.WebcamOpenTask.open(WebcamOpenTask.java:20)
    at com.github.sarxos.webcam.Webcam.open(Webcam.java:189)
    at com.github.sarxos.webcam.Webcam.open(Webcam.java:149)
    at com.github.sarxos.webcam.WebcamPanel.start(WebcamPanel.java:566)
    at com.github.sarxos.webcam.WebcamPanel.<init>(WebcamPanel.java:515)
    at com.github.sarxos.webcam.WebcamPanel.<init>(WebcamPanel.java:476)
    at com.github.sarxos.webcam.WebcamPanel.<init>(WebcamPanel.java:465)
    at main.Main.main(Main.java:12)
    ... 5 more
Caused by: java.lang.NullPointerException
    at com.github.sarxos.webcam.ds.buildin.natives.OpenIMAJGrabber.startSession(Native Method)
    at com.github.sarxos.webcam.ds.buildin.WebcamDefaultDevice.open(WebcamDefaultDevice.java:253)
    at com.github.sarxos.webcam.ds.cgt.WebcamOpenTask.handle(WebcamOpenTask.java:38)
    at com.github.sarxos.webcam.WebcamProcessor$AtomicProcessor.run(WebcamProcessor.java:66)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615)
    at java.lang.Thread.run(Thread.java:724)

Sorry for the bad text wrapping.
Any idea of what I am doing wrong?

[shahbaz-]

My code:

public static void main(String[] args) {

    WebcamPanel panel = new WebcamPanel(Webcam.getWebcams().get(0));
    panel.setFPSDisplayed(true);

    JFrame frame = new JFrame("Webcam Capture Demo");
    frame.add(panel);
    frame.pack();
    frame.setVisible(true);
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
}

[shahbaz-]

Also I used the libs that came with the JAR. I ran the program and got the from /tmp/BridjExtractedLibraries-********/. The program wouldn't even load the libraries otherwise.

[shahbaz-]

Thanks for the reply. I'll try to recompile the OpenImaj binaries.

[sarxos]

Hi @shahbaz-

Please put the recompiled binaries in the same directory as your application - it will then use OpenIMAJGrabber.so instead of the one embedded in JAR.

Please let me know if this fixed your issue.

[shahbaz-]

Still the exact same issue. Still getting an InvocationTargetException when I run it.

[shahbaz-]

I also tried letting it use the Bridj library with the JAR. Still no luck.

[shahbaz-]

Your getting the exception when constructing OpenIMAJ. It should be constructed OpenIMAJ(int, int, double). I'll try to look into the source of webcam-capture and OpenIMAJ.
EDIT: On line 56 of WebcamDefaultDriver.java you start OpenIMAJ with no params. When I ran the program another time it said that it should be constructed with the params above. Makes no sense to me because the OpenImaj.java constructor you have doesn't require any params.

[He-Pin]

hi,the armhf is ok,I have done this before,
and the performance is so low ,especially when you want send the image via Network.

[sarxos]

@shahbaz-, the InvocationTargetException is caused directly by the NPE in OpenIMAJGrabber.startSession(Native Method) and the warning about the missing params you saw is just some rubbish message which has been already fixed in newer BridJ (in 0.6.3 and above).

[shahbaz-]

Ok.What else could I try to do to fix it?