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JRuby and vlcj – A Simple Full-Screen Media Player

jRuby
by: Patrick Bacon

I recently spent some time writing a simple program to play a movie file full screen on a Linux machine. I wrote the program in JRuby using the vlcj framework, which wraps the VLC media player library libVLC.

There are a number of vlcj fullscreen examples around, including an example that comes with the vlcj source code. I had not done much JRuby/Java interop work, so it still took some work for me to get this working in JRuby. To save someone else from the same problems, I thought I would share my work here.

The following script expects the vlcj jars to be in the same directory, and expects libvlc to be installed in a standard location on the machine. The first argument to the script is expected to be the path to a movie file (e.g. movie_trailer.mp4), which will be played full screen with no window decoration.

require File.expand_path(File.dirname(__FILE__)) + "/vlcj-2.1.0.jar"

java_import Java::UkCoCapricaVlcjBinding::LibVlc
java_import Java::UkCoCapricaVlcjPlayer::MediaPlayerFactory
java_import Java::UkCoCapricaVlcjPlayerEmbeddedX::XFullScreenStrategy
java_import Java::UkCoCapricaVlcjRuntime::RuntimeUtil

java_import java.awt.Canvas
java_import java.awt.Color
java_import java.awt.BorderLayout

java_import javax.swing.SwingUtilities
java_import javax.swing.JFrame

java_import com.sun.jna.Native

class MediaPlayer
  def initialize
    library_name = RuntimeUtil.get_lib_vlc_library_name

    # If libvlc is not in a default search path add the path
    # NativeLibrary.add_search_path library_name, "/path/to/libvlc"

    Native.loadLibrary(library_name, LibVlc.java_class)
  end

  def play(mrl)
    SwingUtilities.invokeLater do
      play_movie mrl
    end
  end

  private

  def play_movie(mrl)
    media_player = build_media_player
    media_player.play_media mrl
  end

  def build_media_player
    libvlc_args = [
      "--no-plugins-cache",
      "--no-video-title-show",
      "--no-snapshot-preview",
      "--quiet",
      "--quiet-synchro",
      "--intf",
      "dummy"
    ]

    # Set up the Swing UI
    frame = JFrame.new("Media Player")
    frame.background = Color::BLACK
    canvas = Canvas.new
    canvas.background = Color::BLACK
    frame.add(canvas, BorderLayout::CENTER)
    frame.undecorated = true
    frame.visible = true

    # Set up vlcj
    media_player_factory = MediaPlayerFactory.new(libvlc_args)
    media_player = media_player_factory.new_embedded_media_player(XFullScreenStrategy.new(frame))
    media_player.video_surface = media_player_factory.new_video_surface(canvas)

    media_player.full_screen = true

    media_player
  end
end

MediaPlayer.new.play ARGV[0]

This is the simplest player possible, but there are *tons* of options for making something more sophisticated. And thanks to JRuby and vlcj writing a media player can be done from the comfort of a Ruby program.
 

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