Remote Music Player

This program is a music player that can be controlled remotely via a web interface. My use case is very simple: I have a desktop PC hooked up to a TV and speakers, and I'd like to be able to control what plays on the speakers using my laptop or cell phone. There is probably some existing program that I could use to accomplish this task, but I thought it would be a fun little programming project.

How to Use

The program is a Maven project in the remote-music-player subdirectory. You can launch the music player by running the following command from that directory:

mvn clean javafx:run

In order to run the music player and play music successfully, you'll need to edit config.xml to change the baseDir element to contain the path of the top-level directory holding your music files.

The music player provides a web interface that you can use to remotely control playback. It uses the ports specified in config.xml. To open the web interface, use a web browser to connect to the HTTP port listed in the config file. For example, if the HTTP port is set to 8080 on a computer with IP address 192.168.0.1, then you can access the web interface by navigating a web browser to http://192.168.0.1:8080.

Local Music Browser (work-in-progress)

I have started working on an interface for controlling the music player from the local computer using an Xbox controller. With this feature, the music player could be controlled either from another device or from the computer itself. I'm using the JXInput library to read controller input. My plan is to implement this feature gradually without breaking any existing functionality. When I'm done implementing it, I'll update this README to reflect its presence.

Using JavaFX with Maven

The JavaFX documentation provides some quick-start instructions for using JavaFX with Maven but doesn't explain the example in depth, so it took me a little while to figure out which bits of the example are necessary. Below are some notes about what I discovered.

It looks like in order to have your program successfully reference JavaFX classes, your pom.xml file needs to have the javafx-maven-plugin plugin with a mainClass configuration element set to your program's main class, and you need to launch the program using mvn javafx:run. If you just try to run mvn package and then run the program with java, you'll get a NoClassDefFoundError.

Furthermore, in order to use the JavaFX MediaPlayer class to play media, you need to create and use it inside of a class that extends JavaFX's Application rather than an ordinary command-line program with a main() method. Attempting the latter will give you an IllegalStateException saying "Toolkit not initialized." However, you do not have to actually create and show a Scene inside of the Application's start() method in order to play media.

I would like to make an executable JAR file, but I can't figure out how to make one that works properly with JavaFX. It seems like there is a way to do so with a modular JavaFX project and jlink, but I can't get it to work. For now, I've created a batch script that just calls mvn javafx:run to launch the program on Windows.

Project history

Originally, I wanted to write an app that would capture audio from one computer and stream it to another computer (so that I could capture audio on my laptop and stream it to my desktop). However, after reading these StackOverflow posts, I began to suspect that capturing audio from the sound card is not possible, at least in Java and using my current hardware:

• https://stackoverflow.com/q/2869898
• https://stackoverflow.com/q/44604880

As a result, I switched gears to make a program that plays locally stored mp3 files, with file selection and playback controlled by a web interface. This approach has the downside that I can't play songs from Apple Music or YouTube, but it has the advantage of supporting a wider range of client devices, like a smartphone or tablet.

Helpful links

Playing sound files with Java:

• https://stackoverflow.com/q/6045384
• https://openjfx.io/openjfx-docs/

Running a Java HTTP server with embedded Jetty:

• https://www.eclipse.org/jetty/documentation/current/advanced-embedding.html
• https://www.eclipse.org/jetty/documentation/current/maven-and-jetty.html

Using WebSockets:

• https://developer.mozilla.org/en-US/docs/Web/API/WebSockets_API
• https://github.com/TooTallNate/Java-WebSocket
• https://stackoverflow.com/questions/37857272/invalidstateerror-on-websocket-object

Using JSON:

• https://developer.mozilla.org/en-US/docs/web/javascript/reference/global_objects/json
• https://github.com/google/gson

Styling a web page with CSS:

• https://developer.mozilla.org/en-US/docs/Learn/CSS

Running code on the JavaFX Application Thread:

• https://noblecodemonkeys.com/switching-to-the-gui-thread-in-javafx/

Capturing device audio (old project plan):

• https://stackoverflow.com/q/31738072
• https://stackoverflow.com/q/28122097
• https://docs.oracle.com/javase/tutorial/sound/sampled-overview.html