Generate MP4 video file by sequence PNG images in Java 8

Question

After testing several tools for Windows 10 found on the network, I had great difficulty in finding one that could carry around 5,000 PNG images in sequence and convert it into a video that was transmitted at the speed I wanted. I wasted a lot of time on something that is apparently simple.

The known ffmpeg would be a good alternative, but it did not work on my Windows 10 (permission denied). I tested a lot of free software, but most of it crashed or closed abruptly.

Until others can suggest a good solution here, preferably free, I will post my answer below, with a solution built on Java 8 itself.

Answer 1

Below my simple solution in Java 8 using NIO and JCodec.

1. JCodec maven dependencies

   <dependency>
       <groupId>org.jcodec</groupId>
       <artifactId>jcodec</artifactId>
       <version>0.2.2</version>
   </dependency>
   <dependency>
       <groupId>org.jcodec</groupId>
       <artifactId>jcodec-javase</artifactId>
       <version>0.2.2</version>
   </dependency>
   

2. JCodecPNGtoMP4.java source

   /**
    * Using NIO e JCodec to convert multiple sequence png images to mp4 video file
    * Copyright (C) 2019  Leonardo Pereira (www.leonardopereira.com.br)
    *
    * This program is free software: you can redistribute it and/or modify
    * it under the terms of the GNU General Public License as published by
    * the Free Software Foundation, either version 3 of the License, or
    * (at your option) any later version.
    *
    * This program is distributed in the hope that it will be useful,
    * but WITHOUT ANY WARRANTY; without even the implied warranty of
    * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    * GNU General Public License for more details.
    *
    * You should have received a copy of the GNU General Public License
    * along with this program.  If not, see <http://www.gnu.org/licenses/>.
    */
   import java.awt.image.BufferedImage;
   import java.io.File;
   import java.nio.file.DirectoryStream;
   import java.nio.file.Files;
   import java.nio.file.Path;
   import java.nio.file.Paths;
   import java.util.ArrayList;
   import java.util.Arrays;
   import java.util.Comparator;
   import java.util.List;
   
   import javax.imageio.ImageIO;
   
   import org.jcodec.api.awt.AWTSequenceEncoder;
   import org.jcodec.common.io.NIOUtils;
   import org.jcodec.common.io.SeekableByteChannel;
   import org.jcodec.common.model.Rational;
   
   /**
    * @author Leonardo Pereira
    * 18/03/2019 23:01
    */
   public class JCodecPNGtoMP4 {
   
       private static void sortByNumber(File[] files) {
           Arrays.sort(files, new Comparator<File>() {
               @Override
               public int compare(File o1, File o2) {
                   int n1 = extractNumber(o1.getName());
                   int n2 = extractNumber(o2.getName());
                   return n1 - n2;
               }
               private int extractNumber(String name) {
                   int i = 0;
                   try {
                       int s = name.lastIndexOf('_')+1;
                       int e = name.lastIndexOf('.');
                       String number = name.substring(s, e);
                       i = Integer.parseInt(number);
                   } catch(Exception e) {
                       i = 0; // if filename does not match the format then default to 0
                   }
                   return i;
               }
           });
           /*
           for(File f : files) {
               System.out.println(f.getName());
           }
           */
       }
   
       private static void generateVideoBySequenceImages(String videoFilename, String pathImages, String imageExt) throws Exception {
           SeekableByteChannel out = null;
           try {
               out = NIOUtils.writableFileChannel(videoFilename);
   
               // for Android use: AndroidSequenceEncoder
               AWTSequenceEncoder encoder = new AWTSequenceEncoder(out, Rational.R(25, 1));
   
               Path directoryPath = Paths.get(new File(pathImages).toURI());
   
               if (Files.isDirectory(directoryPath)) {
                   DirectoryStream<Path> stream = Files.newDirectoryStream(directoryPath, "*." + imageExt);
   
                   List<File> filesList = new ArrayList<File>();
                   for (Path path : stream) {
                       filesList.add(path.toFile());
                   }
                   File[] files = new File[filesList.size()];
                   filesList.toArray(files);
   
                   sortByNumber(files);
   
                   for (File img : files) {
                       System.err.println("Encoding image " + img.getName());
                       // Generate the image, for Android use Bitmap
                       BufferedImage image = ImageIO.read(img);
                       // Encode the image
                       encoder.encodeImage(image);
                   }
               }
               // Finalize the encoding, i.e. clear the buffers, write the header, etc.
               encoder.finish();
           } finally {
               NIOUtils.closeQuietly(out);
           }
       }
   
       public static void main(String[] args) throws Exception {
           String videoFilename = "C:/outputVideo.mp4";
           String pathImages = "C:/pathImages";
           generateVideoBySequenceImages(videoFilename, pathImages, "png");
       }
   }