CODEWITHSUNDEEP
javavideo-streamingvlcvlcj
anvijost
anvijost

Reputation: 1

Streaming Desktop in VLCJ

I'm trying to write a Java program which allows one user to act as a server and stream their desktop (video & audio), then other users act as clients and watch the live stream of their desktop (similar to Twitch, Webex, Skype screenshare, etc). I am using VLCJ for this, although I have no commitment to using it so if there is a better solution I'm all ears. Here is the code, which is copied from the link I provide below:

package test.java;

import uk.co.caprica.vlcj.discovery.NativeDiscovery;
import uk.co.caprica.vlcj.player.MediaPlayerFactory;
import uk.co.caprica.vlcj.player.headless.HeadlessMediaPlayer;
import test.java.VlcjTest;

/**
* An example of how to stream a media file over HTTP.
* <p>
* The client specifies an MRL of <code>http://127.0.0.1:5555</code>
*/
public class StreamHttp extends VlcjTest {

    //when running this it requires an MRL (Media Resource Locator)
    //fancy term for saying the file you want to stream. This could be a url to another
    //location that streams media or a filepath to a media file you want to stream
    //on the system you are running this code on.
    public static void main(String[] args) throws Exception {
        new NativeDiscovery().discover();
        if(args.length != 1) {
            System.out.println("Specify a single MRL to stream");
            System.exit(1);
        }

        //the media you are wanting to stream
        String media = args[0];
        //this is the IP address and port you are wanting to stream at
        //this means clients will connect to http://127.0.0.1:5555
        //to watch the stream
        String options = formatHttpStream("127.0.0.1", 5555);

        System.out.println("Streaming '" + media + "' to '" + options + "'");

        //this creates a the actual media player that will make calls into the native
        //vlc libraries to actually play the media you supplied. It does it in
        //a headless fashion, as you are going to stream it over http to be watched
        //instead of playing it locally to be watched.    
        MediaPlayerFactory mediaPlayerFactory = new MediaPlayerFactory(args);
        HeadlessMediaPlayer mediaPlayer = mediaPlayerFactory.newHeadlessMediaPlayer();

        //this simply starts the player playing the media you gave it
        mediaPlayer.playMedia(media, options);

        // Don't exit
        //basically you don't want the thread to end and kill the player, 
        //so it just hangs around and waits for it to end.
        Thread.currentThread().join();
    }

    private static String formatHttpStream(String serverAddress, int serverPort) {
        StringBuilder sb = new StringBuilder(60);
        sb.append(":sout=#duplicate{dst=std{access=http,mux=ts,");
        sb.append("dst=");
        sb.append(serverAddress);
        sb.append(':');
        sb.append(serverPort);
        sb.append("}}");
        return sb.toString();
    }
}

I pass "screen://" as a parameter to this program. When I run the code, I get this error message:

[000000000038b250] access_output_http access out: Consider passing --http-host=IP on the command line instead.
[000000001ccaa220] core mux error: cannot add this stream
[000000001cc72100] core decoder error: cannot create packetizer output (RV32)

I tried searching for a solution but all I could find was this: Video Streaming in vlcj and although this user had the same error, I couldn't solve my problem from this link, although I did use the StreamHttp code sample from it. I am a relatively inexperienced programmer so if I missed an obvious solution then I apologize. I am using Java 1.8, Windows 7 64 bit.

Upvotes: 0

Views: 1174

Answers (1)

caprica
caprica

Reputation: 4146

You need something like this:

String media = "screen://";
String[] options = {
    ":sout=#transcode{vcodec=FLV1,vb=4096,scale=0.500000}:http{mux=ffmpeg{mux=flv},dst=:5000/"
};

The key things shown here are a "sout" string to transcode the video, then another appended "sout" string to stream (in this case via http).

In this example string, for http streaming only the port (5000, arbitrarily chosen) is specified. No host is specified, so it means localhost. You could have something like "dst=127.0.0.1:8080/" or whatever you need.

You will have to choose/experiment with the specific transcoding/streaming options that you want. There is no one size fits all for those options.

Foot-note:

You can actually use VLC itself to generate this string for you.

Start VLC, then choose the media you want to play.

Instead of pressing "Play", use the widget to select "Stream" instead. This opens the Streaming wizard where you can pick all of your options.

At the end of the wizard, before you start playing, it shows you the string you need.

Upvotes: 1

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