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• FFMPEG : Generate 7.1 channel audio file with the longest time of input file

  10 juin 2020, par Anthony

  I want to use ffmpeg to generate 7.1 channel audio file from 8 different audio files.
But I found the output file's duration is decided by the input file with shortest duration.
I didn't find any parameter to auto-pad the shorter audio file or choose the longest duration as final duration.

  



  I already have seen the offlical document as below.
https://ffmpeg.org/ffmpeg-all.html
https://trac.ffmpeg.org/wiki/AudioChannelManipulation
But nothing is helpful.

  



  This is the command I use right now :

  



  ffmpeg -i fl.wav -i fr.wav -i fc.wav -i lfe.wav -i bl.wav -i bl.wav -i sl.wav -i sr.wav -filter_complex "[0:a][1:a][2:a][3:a][4:a][5:a][6:a][7:a]join=inputs=8:channel_layout=7.1[a]" -map "[a]" output.wav

  


• Java open CV hangs on VideoCapture for file if openCV is loaded with nu.pattern.OpenCV.loadShared() ;

  30 septembre 2020, par Ilya Yevlampiev

  I have a sample code from https://ratiler.wordpress.com/2014/09/08/detection-de-mouvement-avec-javacv/ with small difference in loading the open cv library in the static block using nu.pattern.OpenCV.loadShared(); :

  


  import java.awt.image.BufferedImage;
import java.io.ByteArrayInputStream;
import java.io.IOException;
import java.io.InputStream;

import javax.imageio.ImageIO;
import javax.swing.ImageIcon;
import javax.swing.JFrame;
import javax.swing.JLabel;

import org.opencv.core.CvType;
import org.opencv.core.Mat;
import org.opencv.core.MatOfByte;
import org.opencv.core.Size;
import org.opencv.imgcodecs.Imgcodecs;
import org.opencv.videoio.VideoCapture;
import org.opencv.imgproc.Imgproc;

public class JavaCVPrjt01 {
    static {
        //System.loadLibrary(Core.NATIVE_LIBRARY_NAME);
        nu.pattern.OpenCV.loadShared();
    }
    public static void main(String[] args) {
        JFrame jframe = new JFrame("HUMAN MOTION DETECTOR FPS");
        jframe.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        JLabel vidpanel = new JLabel();
        jframe.setContentPane(vidpanel);
        jframe.setSize(1280,720) ;
        jframe.setVisible(true);

        Mat frame = new Mat();
        Mat outerBox = new Mat();
        Size sz = new Size(1280,720);
        VideoCapture camera = new VideoCapture("D:/Downloads/video4.mp4");

        while (true) {
            if (camera.read(frame)) {
                Imgproc.resize(frame,frame, sz );
                outerBox = new Mat(frame.size(), CvType.CV_8UC1);
                Imgproc.cvtColor(frame, outerBox, Imgproc.COLOR_BGR2GRAY);
                Imgproc.GaussianBlur(outerBox, outerBox, new Size(3, 3), 0);

                ImageIcon image = new ImageIcon(Mat2bufferedImage(outerBox));
                vidpanel.setIcon(image);
                vidpanel.repaint();

            }
        }
    }

    public static BufferedImage Mat2bufferedImage(Mat image) {
        MatOfByte bytemat = new MatOfByte();
        Imgcodecs.imencode(".jpg", image, bytemat);
        byte[] bytes = bytemat.toArray();
        InputStream in = new ByteArrayInputStream(bytes);
        BufferedImage img = null;
        try {
            img = ImageIO.read(in);
        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        return img;
    }

}


  


  and of course, the needed dependencies were added :

  


      <dependency>&#xA;        <groupid>org.bytedeco.javacpp-presets</groupid>&#xA;        <artifactid>opencv</artifactid>&#xA;        <version>3.2.0-1.3</version>&#xA;    </dependency>&#xA;&#xA;    <dependency>&#xA;        <groupid>org.openpnp</groupid>&#xA;        <artifactid>opencv</artifactid>&#xA;        <version>3.2.0-1</version>&#xA;    </dependency>&#xA;

  


  so, code is executed right before

  


  VideoCapture camera = new VideoCapture("D:/Downloads/video4.mp4");


  


  where it hangs and I have no clues to check what is wrong on the JNI level there.

  


• How can I analyze file and detect if the file is in H.264 video format ? [on hold]

  5 octobre 2016, par codeDom

  I write software C/C++ to recover deleted files, and I need to identify files according to their binary content, so my question is there a simple way to know if a particular file is H.264 format video ? is H.264 has an signature ?

  I saw the code of FFMPEG here, but can it help me, how ?