Image is distorted when converting from OpenCVFrameConverter.ToOrgOpenCvCoreMat using a mp4 video

[MachineIntelligence6]

Im trying to converting Frame from to Mat but the image is distorted. below is the link of the video and code.

`package com.mi6.surf;

import org.bytedeco.ffmpeg.global.avutil;
import org.bytedeco.javacv.FFmpegFrameGrabber;
import org.bytedeco.javacv.Frame;
import org.bytedeco.javacv.FrameGrabber.Exception;
import org.bytedeco.javacv.OpenCVFrameConverter;
import org.opencv.core.Mat;

public class Grabber {

private FFmpegFrameGrabber grabber;

private final OpenCVFrameConverter.ToOrgOpenCvCoreMat converter;

public Grabber() {
	avutil.av_log_set_level(avutil.AV_LOG_QUIET);
	converter = new OpenCVFrameConverter.ToOrgOpenCvCoreMat();
}

public void setVideo(String videoFilename) throws Exception {
	System.out.println("Setting Video in Grabber. ");
	grabber = new FFmpegFrameGrabber(videoFilename);
	
	System.out.println("Starting Grabber. ");
	grabber.start();
}

public long getTotalTime() {
	return grabber.getLengthInTime();
}

public Mat getFrameAt(long timestamp) throws Exception {
	System.out.println("Getting Frame at "+ timestamp);
	grabber.setTimestamp(timestamp);
	Frame frame = grabber.grabImage();
	
	if(frame==null || frame.imageWidth ==0 || frame.imageHeight==0)
		throw new Exception("Cannot Extract Frame at timestamp: "+ timestamp);
	
	return converter.convert(frame);
}

public void stopGrabber() throws Exception {
	System.out.println("Stopping Grabber. ");
	grabber.stop();
}

}

`package com.mi6.opencv;

import org.bytedeco.javacpp.Loader;
import org.bytedeco.javacv.FrameGrabber.Exception;
import org.bytedeco.opencv.opencv_java;
import org.opencv.core.Mat;
import org.opencv.highgui.HighGui;

import com.mi6.surf.Grabber;

/**

• Hello world!

*/
public class Test2 {

public static void main(String[] args) throws Exception {
	
	Loader.load(opencv_java.class);
	
	String videoFilename = "C:\\Users\\Mi6\\Desktop\\Jobs 2013.mp4";

	long timestamp = (long) ((2) * 1000_000); //2 sec

	Grabber grabber = new Grabber();

	grabber.setVideo(videoFilename);
	
	Mat objectImage = grabber.getFrameAt(timestamp).clone();
	
	HighGui.imshow("Object Image", objectImage);
	HighGui.waitKey(0);
	
}

}
[Distorted Image](https://1drv.ms/u/s!As2o7s_R_SwDghtwCI07dH87epJI?e=H8tMQG)
Video Link

[saudet]

That's a known limitation of the official Java API. Don't use it if you need custom strides like this, or please report upstream.

[MachineIntelligence6]

If I use same video and extract frame from java2Dframeconverter and save bufferedimage, I get correct image. If we use OpenCVFrameConverter and get Mat image and save it the image get distorted and give schew/stretch or distort image. I think there is some problem with open cv converter.

[saudet]

Like I said, this is a problem with the Java API of OpenCV. There is no such limitations with the C++ API of OpenCV. Instead of using Java API, please use the C++ API, and you will not have this issue.

If you cannot use the C++ API of OpenCV, there is nothing else I can do here. Please report this issue upstream.

[MachineIntelligence6]

ok got it now, i was thinking there was problem with java from your last comment, but its now clear to me its problem with Java API of OpenCV, i will try to find a work around and report this error. Thank you

[saudet]

Actually, it looks like the Java API was fixed. There's a new constructor that we can use to set the stride here:
http://bytedeco.org/javacpp-presets/opencv/apidocs/org/opencv/core/Mat.html#Mat-int-int-int-java.nio.ByteBuffer-long-
I've updated OpenCVFrameConverter in the last commit. Please give it a try with the snapshots: http://bytedeco.org/builds/

[MachineIntelligence6]

Thank you, working perfectly.