Webcam Capture API -How to get it work on Raspberry Pi?

Question

This is my first post in stackoverflows forum.

I like to refer this sarxos answer https://stackoverflow.com/a/31871593/5510077

I think I have followed API's creator Bartosz Firyns instructions exactly to get his Webcam Capture 0.3.10 API to work on my Raspberry Pi Model B+.

Files I have currently included in my classpath are:

• slf4j-api-1.7.2.jar
• slf4j-simple-1.7.2.jar
• v4l4j-0.9.1-r507.jar
• webcam-capture-0.3.10.jar
• webcam-capture-driver-v4l4j-0.3.10-20140923.154112-11.jar

I use this sarxos's example to test API, but using V4l4jDriver, because I can't get BridJ work on Raspberry Pi :

package webcam;

import java.awt.image.BufferedImage;
import java.io.File;
import java.io.IOException;
import javax.imageio.ImageIO;
import com.github.sarxos.webcam.Webcam;
import com.github.sarxos.webcam.ds.v4l4j.V4l4jDriver;

public class WebCam {

    static {
        Webcam.setDriver(new V4l4jDriver()); // this is important
    }

    public static void main(String[] args) throws IOException {

        // get default webcam and open it
        Webcam webcam = Webcam.getDefault();
        webcam.open();

        // get image
        BufferedImage image = webcam.getImage();

        // save image to PNG file
        ImageIO.write(image, "PNG", new File("test.png"));
    }
}

and receive this error:

[main] WARN com.github.sarxos.webcam.ds.v4l4j.V4l4jDriver - Modified V4L4J has not been found in classpath
Exception in thread "main" com.github.sarxos.webcam.WebcamException: java.util.concurrent.ExecutionException: java.lang.NullPointerException
    at com.github.sarxos.webcam.WebcamDiscoveryService.getWebcams(WebcamDiscoveryService.java:124)
    at com.github.sarxos.webcam.Webcam.getWebcams(Webcam.java:816)
    at com.github.sarxos.webcam.Webcam.getDefault(Webcam.java:879)
    at com.github.sarxos.webcam.Webcam.getDefault(Webcam.java:856)
    at com.github.sarxos.webcam.Webcam.getDefault(Webcam.java:834)
    at webcam.WebCam.main(WebCam.java:34)
Caused by: java.util.concurrent.ExecutionException: java.lang.NullPointerException
    at java.util.concurrent.FutureTask.report(FutureTask.java:122)
    at java.util.concurrent.FutureTask.get(FutureTask.java:192)
    at com.github.sarxos.webcam.WebcamDiscoveryService.getWebcams(WebcamDiscoveryService.java:116)
    ... 5 more
Caused by: java.lang.NullPointerException
    at com.github.sarxos.webcam.util.NixVideoDevUtils.getVideoFiles(NixVideoDevUtils.java:19)
    at com.github.sarxos.webcam.ds.v4l4j.V4l4jDriver.getDevices(V4l4jDriver.java:46)
    at com.github.sarxos.webcam.WebcamDiscoveryService$WebcamsDiscovery.call(WebcamDiscoveryService.java:36)
    at com.github.sarxos.webcam.WebcamDiscoveryService$WebcamsDiscovery.call(WebcamDiscoveryService.java:26)
    at java.util.concurrent.FutureTask.run(FutureTask.java:266)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
    at java.lang.Thread.run(Thread.java:745)
Java Result: 1

These links are dead so I can't test these jar-files:

webcam-capture-0.3.11-SNAPSHOT.jar

webcam-capture-driver-v4l4j-0.3.11-20150713.101304-10.jar

Is there anything to do to get this API working on Raspberry Pi on these days?

Answer 1

You get rid of the error and application running when you replace two files:

webcam-capture-0.3.10.jar

with this one:

webcam-capture-0.3.11.jar

and

webcam-capture-driver-v4l4j-0.3.10-20140923.154112-11.jar

with this one

webcam-capture-driver-v4l4j-0.3.11.jar

Links to these files and answered ticket from Webcam Capture API author to missing links.

Answer 2

the program above is causing lots of error on latest rpi. please use the following example https://blogs.msdn.microsoft.com/robert_mcmurray/2015/06/12/simple-java-wrapper-class-for-raspistill-on-the-raspberry-pi-2/