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Cannot open/view/grab/read IP Camera using OpenCV

I am using OpenCV to grab an IP Camera's stream and frames. Here is a snippet of my code:
import org.opencv.core.Core;
import org.opencv.core.Mat;
import org.opencv.imgproc.Imgproc;
import org.opencv.videoio.VideoCapture;
import org.opencv.videoio.Videoio;
import org.opencv.imgcodecs.*;
import org.opencv.core.Rect;
import org.opencv.core.Size;
public class Main {
public static void main(String[] args) {
String newCameraIP = "http://10.12.18.11/mjpg/video.mjpg";
VideoCapture cap = new VideoCapture();
if (cap.open(newCameraIP)) {
System.out.println("Camera opened from " + newCameraIP);
} else {
System.out.println("No camera found at " + newCameraIP + ". Trying USB ports...");
}
USB cameras work fine but when I try to use an IP Camera, I receive the following error message:
VIDEOIO(cvCreateFileCapture_AVFoundation (filename)): raised unknown C++ exception!

I just had this exact problem using Python on OSX. The solution for me was to rebuild opencv using the --with-ffmpeg flag.

Incomplete java.net.URL.openStream() stream

I’m using java.net.URL.openStream() to access a HTTPS resource. The returned stream is incomplete for some URLs: for the example below, it yields a 1,105,724 byte-file whereas the same URL accessed from a browser yields a 5,755,858 byte-file (even when "disabling" Content-Encoding).
And it doesn’t even throw an exception.
What am I missing?
import static java.nio.file.Files.copy;
import java.io.IOException;
import java.io.InputStream;
import java.net.URL;
import java.nio.file.Paths;
public class Test {
public static void main(String... args) throws IOException {
try (final InputStream in = new URL(
"https://upload.wikimedia.org/wikipedia/commons/9/95/Germany_%28orthographic_projection%29.svg").openStream()) {
copy(in, Paths.get("germany.svg"));
}
}
}
Edit
I’ve tested this code a lot of times (on different networks, but always on JRE 1.8.0_60 / Mac OS X 10.11.4), and sometimes it’s suddenly "starting to work".
However, switching to another of my problematic URLs (e.g. "https://upload.wikimedia.org/wikipedia/commons/c/ce/Andorra_in_Europe_%28zoomed%29.svg") enables me to reproduce the issue.
Does this mean that it is a server issue? I’ve never seen it on a browser though.

It's working fine.
As others have suggested there may be a problem with your network, try connecting to another network.
package test;
import java.io.InputStream;
import java.net.URL;
import java.nio.file.Files;
import java.nio.file.Path;
import java.nio.file.Paths;
import java.nio.file.StandardCopyOption;
public class TestMain2 {
public static void main(String[] args) {
System.out.println("Started");
try (final InputStream in = new URL(
"https://upload.wikimedia.org/wikipedia/commons/9/95/Germany_%28orthographic_projection%29.svg")
.openStream()) {
Path outputFile = Paths.get("test.svg");
Files.copy(in, outputFile, StandardCopyOption.REPLACE_EXISTING);
System.out.println("Output file size : " + outputFile.toFile().length());
System.out.println("Finished");
} catch (Exception ex) {
ex.printStackTrace();
}
}
}
Output
Started
Output file size : 5755858
Finished

Decoding .webm format doesn't return any BufferedImages

My code here is compiling correctly, but I am running into the problem that my ArrayList of BufferedImages is always empty. Honestly I don't have any knowledge regarding ImageIO or the likes!
import java.awt.image.BufferedImage;
import java.io.File;
import java.io.IOException;
import java.util.ArrayList;
import javax.imageio.IIOException;
import javax.imageio.ImageIO;
import javax.imageio.ImageReader;
import net.sf.javavp8decoder.imageio.WebPImageReader;
import net.sf.javavp8decoder.imageio.WebPImageReaderSpi;
class MyProj{
public static void main(String[] args) throws IOException{
System.out.println("Main");
ArrayList<BufferedImage> collectedImg=getFrames();
}
static ArrayList<BufferedImage> getFrames() throws IIOException{
File MyWebM= new File("/users/case3/mcclusm4/workspace/LineTech/src/goal.webm");
ArrayList<BufferedImage> frames = new ArrayList<BufferedImage>();
try{
ImageReader ir = new WebPImageReader(new WebPImageReaderSpi());
ir.setInput(ImageIO.createImageInputStream(MyWebM));
for(int i = 0; i < ir.getNumImages(true); i++)
frames.add(ir.read(i));
}catch(IOException e){}
return frames;
}
}

First of all dont catch Exception and do nothing:
catch (Exception e) {}
Now when an exception is catched it silently fails without any information.
Change catch to print stacktrace: e.printStackTrace() and post it.

Disclaimer: I have never tested the code in question myself. But...
From looking at the source code of net.sf.javavp8decoder.imageio.WebPImageReader it cannot decode WebM files. It only supports single frame WebP files.
If you stop swallowing the exception and ignoring it, as suggested by #robocoder, you should get an IIOException with the message "Bad WEBP signature!".

How to setup zxing library on Windows 8 machine?

I have images of codes that I want to decode. How can I use zxing so that I specify the image location and get the decoded text back, and in case the decoding fails (it will for some images, that's the project), it gives me an error.
How can I setup zxing on my Windows machine? I downloaded the jar file, but I don't know where to start. I understand I'll have to create a code to read the image and supply it to the library reader method, but a guide how to do that would be very helpful.

I was able to do it. Downloaded the source and added the following code. Bit rustic, but gets the work done.
import com.google.zxing.NotFoundException;
import com.google.zxing.ChecksumException;
import com.google.zxing.FormatException;
import com.google.zxing.BarcodeFormat;
import com.google.zxing.DecodeHintType;
import com.google.zxing.Reader;
import com.google.zxing.BinaryBitmap;
import com.google.zxing.Result;
import com.google.zxing.LuminanceSource;
import com.google.zxing.client.j2se.BufferedImageLuminanceSource;
import com.google.zxing.common.HybridBinarizer;
import java.awt.image.BufferedImage;
import javax.imageio.ImageIO;
import java.io.File;
import java.io.IOException;
import java.util.*;
import com.google.zxing.qrcode.QRCodeReader;
class qr
{
public static void main(String args[])
{
Reader xReader = new QRCodeReader();
BufferedImage dest = null;
try
{
dest = ImageIO.read(new File(args[0]));
}
catch(IOException e)
{
System.out.println("Cannot load input image");
}
LuminanceSource source = new BufferedImageLuminanceSource(dest);
BinaryBitmap bitmap = new BinaryBitmap(new HybridBinarizer(source));
Vector<BarcodeFormat> barcodeFormats = new Vector<BarcodeFormat>();
barcodeFormats.add(BarcodeFormat.QR_CODE);
HashMap<DecodeHintType, Object> decodeHints = new HashMap<DecodeHintType, Object>(3);
decodeHints.put(DecodeHintType.POSSIBLE_FORMATS, barcodeFormats);
decodeHints.put(DecodeHintType.TRY_HARDER, Boolean.TRUE);
Result result = null;
try
{
result = xReader.decode(bitmap, decodeHints);
System.out.println("Code Decoded");
String text = result.getText();
System.out.println(text);
}
catch(NotFoundException e)
{
System.out.println("Decoding Failed");
}
catch(ChecksumException e)
{
System.out.println("Checksum error");
}
catch(FormatException e)
{
System.out.println("Wrong format");
}
}
}

The project includes a class called CommandLineRunner which you can simply call from the command line. You can also look at its source to see how it works and reuse it.
There is nothing to install or set up. It's a library. Typically you don't download the jar but declare it as a dependency in your Maven-based project.
If you just want to send an image to decode, use http://zxing.org/w/decode.jspx

How to get the single images of an mp4-Movie in Java

I want to do some image analysis on a video that's stored in .mp4 format. Therefore I need a way to just get the images of this movie in Java.
I goolged a lot and found some libraries like jcodec and jaad. BUT I wasn't able to get the things running with these libraries. And as I found out, there were examples (at least I found none) that showed my usecase.
Can you help me? Do you know any library that can do what I need and is running at least on Win7 64 bit.
Or do you know how to accomplish this with jcodec?
edit:
As I wrote, I tried it with jcodec. I found out how to get the data of a frame, but not how I can get it into something like a BufferedImage or so. I expect that these data isn't in a simple RGB format but in any compressed format or so. (Am I right with that?) I don't know to to decode this data.
You can get the data of a frame with jcodec as follows (at least as far as I understand this):
public static void main(String[] args) throws IOException, MP4DemuxerException {
String path = "videos/video-2011-09-21-20-07-21.mp4";
MP4Demuxer demuxer1 = new MP4Demuxer(new FileInput(new File(path)));
DemuxerTrack videoTrack = demuxer1.getVideoTrack();
Packet firstFrame = videoTrack.getFrames(1);
byte[] data = firstFrame.getData();
}
I also found the following:
http://code.google.com/p/jcodec/source/browse/trunk/src/test/java/org/jcodec/containers/mp4/DitherTest.java?r=70
But this isn't working (has compile errors) with the downloadable jar-package.

you could use jcodec(https://github.com/jcodec/jcodec) in the followinf program i am extracting frames from a video.
/*
* To extract frames from a mp4(avc) video
*
*/
package avc_frame;
import java.awt.image.BufferedImage;
import java.io.File;
import java.io.IOException;
import javax.imageio.ImageIO;
import org.jcodec.api.FrameGrab;
import org.jcodec.api.JCodecException;
public class Avc_frame {
/**
* #param args the command line arguments
*/
public static void main(String[] args) throws IOException, JCodecException {
long time = System.currentTimeMillis();
for (int i = 50; i < 57; i++) {
BufferedImage frame = FrameGrab.getFrame(new File("/Users/jovi/Movies/test.mp4"), i);
ImageIO.write(frame, "bmp", new File("/Users/jovi/Desktop/frames/frame_"+i+".bmp"));
}
System.out.println("Time Used:" + (System.currentTimeMillis() - time)+" Milliseconds");
}
}

import java.awt.image.BufferedImage;
import java.io.File;
import java.io.IOException;
import javax.imageio.ImageIO;
import org.bytedeco.javacpp.opencv_core.IplImage;
import org.bytedeco.javacv.FFmpegFrameGrabber;
import org.bytedeco.javacv.FrameGrabber.Exception;
public class Read{
public static void main(String []args) throws IOException, Exception
{
FFmpegFrameGrabber frameGrabber = new FFmpegFrameGrabber("C:/Users/Digilog/Downloads/Test.mp4");
frameGrabber.start();
IplImage i;
try {
i = frameGrabber.grab();
BufferedImage bi = i.getBufferedImage();
ImageIO.write(bi,"png", new File("D:/Img.png"));
frameGrabber.stop();
} catch (Exception e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}