Xuggler "Could not write header" error

Question

I am making a screen recording application with Xuggler. I've basically encapsulated Java Code Geeks' Xuggler tutorial code into a runnable class for the actual recording. It should run just like the tutorial, but I'm getting some (actually a ton of) errors. The link to that code is here: JavaCodeGeeks. I'm not trying to take credit for this entire block of code.

Here is what I have so far:

import java.awt.AWTException;
import java.awt.Dimension;
import java.awt.Rectangle;
import java.awt.Robot;
import java.awt.Toolkit;
import java.awt.image.BufferedImage;
import java.io.File;
import java.util.concurrent.TimeUnit;

import javax.swing.JOptionPane;

import src.dtf.gui.GUI;

import com.xuggle.mediatool.IMediaWriter;
import com.xuggle.mediatool.ToolFactory;
import com.xuggle.xuggler.ICodec;

public class ScreenRecorder implements Runnable {

//Booleans to run and to pause.  (Pausing not implemented yet)
boolean running = true;
boolean paused = false;

//Some variables
private GUI gui;
private Toolkit tk;
private String path, name, outputFilename;
private int fps;
private long startTime;
private Rectangle recArea;
private Dimension bounds;

//Declare the MediaWriter
private IMediaWriter writer;

//Constructor
public ScreenRecorder(GUI gui) {
    //Set the GUI to the one that I'm using (Another class
    this.gui = gui;
    //Initialize variables, based on previous user input.
    tk = Toolkit.getDefaultToolkit();
    path = gui.getPath();
    name = JOptionPane.showInputDialog("Please enter a name for your video file:");
    outputFilename = path + "\\" + name + ".mp4";
    fps = gui.getFPS();
    if (gui.fullscreenChecked()) {
        recArea = new Rectangle(0, 0, tk.getScreenSize().width,
                tk.getScreenSize().height);
    } else {
        recArea = gui.getArea();
    }
    bounds = new Dimension(recArea.width, recArea.height);
}

//Start method
public void start() {
    gui.disableButtons();
    gui.changeRecordButton(false);
    running = true;
}

//Run method
public void run() {
    //Initialize
    init();
    long lastTime = System.currentTimeMillis();
    int updateTime = 1000 / fps;
    startTime = System.nanoTime();
    while (running) {
        //Limit updates
        if (System.currentTimeMillis() - lastTime >= updateTime) {
            //Ensure the recording is not paused
            if (!paused) {
                //If the user has stopped, stop
                if (!gui.isRecording()) {
                    stop();
                }
                //Take a screenshot and convert it
                BufferedImage frame = takeScreenshot();
                BufferedImage bgrScreen = convertImage(frame, BufferedImage.TYPE_3BYTE_BGR);
                //Encode video
                writer.encodeVideo(0, bgrScreen, System.nanoTime() - startTime, TimeUnit.NANOSECONDS);
                System.out.println("Recording...");
            } else if (paused) {
                System.out.println("Paused...");
            }
        }
    }
}


private void init() {
    //Make sure the given directory exists
    checkFile();
    //Ensure there is not already a file of the same name
    checkFilename();
    //Make the writer
    writer = ToolFactory.makeWriter(outputFilename);
    writer.addVideoStream(0, 0, ICodec.ID.CODEC_ID_MPEG4, bounds.width, bounds.height);
}

//Method for checking if the directory exists
private void checkFile() {
    if (!(new File(path).exists())) {
        gui.resetPath();
        JOptionPane.showMessageDialog(gui, "ERROR: File path does not exist!");
        System.out.println("ERRR");
        stop();
    }
}

//Method for checking if the given filename exists
private void checkFilename() {
    if (new File(path + "\\" + name + ".mp4").exists()) {
        JOptionPane.showMessageDialog(gui, "ERROR: File already exists!!");
        stop();
    }
}

//Method for converting the BufferedImage (Thanks JavaCodeGeeks)
private BufferedImage convertImage(BufferedImage b, int targetType) {
    BufferedImage image;
    if (b.getType() == targetType) {
        image = b;
    } else {
        image = new BufferedImage(b.getWidth(), b.getHeight(), targetType);
        image.getGraphics().drawImage(b, 0, 0, null);
    }
    return image;
}

//Method for taking a screenshot
private BufferedImage takeScreenshot() {
    try {
        Robot r = new Robot();
        return r.createScreenCapture(recArea);
    } catch (AWTException e) {
        e.printStackTrace();
        return null;
    }
}

//Stop method
public void stop() {
    gui.enableButtons();
    gui.changeRecordButton(true);
    //Make sure the writer has been initialized. (Not an incorrect filename or anything)
    if (writer != null) {
        //Close the writer
        writer.close();
    }
    //End thread
    running = false;
}

}

And here's the error that's thrown:

17:46:48.076 [Thread-2] ERROR org.ffmpeg - [mp4 @ 000000000028F660] no streams
17:46:48.123 [Thread-2] ERROR com.xuggle.xuggler - Error: could not write header for container (../../../../../../../csrc/com/xuggle/xuggler/Container.cpp:827)

I tried to fix it by adding the isHeaderWritten() if statement in the stop method, but that never gets called at all, so it must be somewhere else (or within that if statement). I don't know what line of my code throws the error, because it only gives me these two errors, which point to Xuggler, not my code. When I execute this, it creates an mp4 file but its size is 0 bytes and the file won't play. I could really use some help because I have no idea what these errors even mean, so it's hard to debug them. Thanks!

Answer 1

We're probably going to get in trouble for not honoring the Q&A-format of this website, so I'm just going to list some things you can try.

• The error you are getting regarding the header is also raised when you don't specifically call writeHeader(). You are also getting an error concerning a 'missing stream'. This suggests that Xuggler is missing some information it needs to properly add the video stream and open the writer. So start by debugging your Java application to figure out which specific line is causing the error.

• Also, try rendering each output frame to a JFrame, just before you write it. This will allow you to verify whether the BufferedImages you want to write have the proper content.

• The file you write to is an MP4, which will make Xuggler draw a couple of conclusions on desired output parameters, but you best not rely on that. Try setting the pixel format, bitrate, frame rate and time base yourself. This is why suggested you use a buffer: you would be able to write frames at a specific interval, which will guarantee the proper frame rate. The way you've set it up now will result in a variable frame rate, which some codecs and containers will not appreciate. The type of buffer isn't that relevant, you could even use an ArrayList. But naturally some data structures will be more efficient than others.

• Some codecs and file containers are a lot more forgiving than others. So try out some other codecs as well, such as H.264. You could try changing the file container as well, but MP4 usually works fine in Xuggler.

• This is unrelated to your current problem, because this has nothing to do with the output file being empty. But you should watch out for the timestamps with which you write frames. The first video frame should be at timestamp 0, but because you capture and encode in the same while-loop, the first frame will have a much higher timestamp. Also, when you pause, your application won't write any frame but the timestamp will still increase. This will cause a 'hole' in your video when you later resume recording, a small time window without any video data.