IsoFileReader.java

import java.io.File;
import java.io.IOException;
import java.io.RandomAccessFile;

/**
 * http://www.file-recovery.com/mp4-signature-format.htm
 */
public class IsoFileReader {
    public static void main(String[] args) throws IOException {
        File file = new File("test1.mp4");
        try(RandomAccessFile reader = new RandomAccessFile(file, "r")) {
            int position = reader.readInt();
            System.out.println(position);
            {
                byte[] mark = new byte[8];
                int len = reader.read(mark);
                String str = new String(mark, 0, len);
                System.out.println(str);
            }
            reader.skipBytes(4);
            {
                byte[] mark = new byte[8];
                int len = reader.read(mark);
                String str = new String(mark, 0, len);
                System.out.println(str);
            }
            reader.seek(0);
            reader.skipBytes(position);
            System.out.println(reader.readInt());
            {
                byte[] mark = new byte[4];
                int len = reader.read(mark);
                String str = new String(mark, 0, len);
                System.out.println(str);
            }
        }
    }
}