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vlcj

vlcj-5 requires VLC 4.0 as a minimum baseline - VLC 4.0 is currently in development and it may be some time before it is released.

If you are looking for a stable combination of vlcj and VLC then switch to the vlcj-4.x branch instead.

vlcj

The vlcj project provides a Java framework to allow an instance of a native VLC media player to be embedded in a Java application.

You get more than just simple bindings, you also get a higher level framework that hides a lot of the complexities of working with LibVLC.

vlcj is primarily developed and therefore extensively tested on Linux - it does also work just fine on Windows and OSX, although there may be some limitations on OSX.

Additionally, whilst not supported as one of the main platforms, this version of vlcj has been tested and shown to be working on contemporary Raspberry Pi builds.

At least JDK 8 is required.

vlcj-4.7.x, which is still current, is the last version of vlcj that was built against JDK 1.6.

This version of vlcj requires VLC 4.0.0 as a minimum, no earlier version is supported.

This is the open source vlcj project page, see also the 'official' home page where you can find more information as well as some new simple tutorials.

Build Status

Continuous Integration

Maven Central

News

Project status update 7th March 2021:

vlcj-5.0.0-SNAPSHOT currently has feature parity with the in-development LibVLC 4.0.0 - we're basically waiting for VLC 4.0 final to be released, or for any new native API to be added to be added to LibVLC.

If you have a stable pre-release build of VLC 4.0.0 you should be fine to use the current vlcj-5.0.0-SNAPSHOT version.

But as of right now, there's nothing much more to be done on vlcj until the next major version of VLC is released - and that is likely yet to be quite some time away.

  • Future, 2021 - vlcj 5.0.0 release, significant changes for LibVLC 4.0.0, minimum Java version now Java 8 LTS.

All releases are at available at Maven Central.

You can follow @capricasoftware on Twitter for more vlcj news.

Swing/AWT, JavaFX, OpenGL

Core vlcj embeds native media players in Swing/AWT applications. This has been the foundation of vlcj since the earliest versions. This is still fully supported and still works well, in fact it is still likely the most performant solution.

However, recent versions of JavaFX introduced the PixelBuffer component, providing direct access to a shared native memory buffer that can be used by vlcj/LibVLC as a "callback" video buffer. This performs really well. even when using multiple concurrent video players.

Another factor to consider here is that contemporary macOS does not support AWT at all, so JavaFX is a very good option on that platform.

For more information see the vlcj-javafx and vlcj-javafx-demo projects.

A further possibility with this "callback" approach to video rendering is that with vlcj-5.x and VLC 4.x it becomes very easy to embed a media player in an OpenGL application. This should give very good playback performance, possibly right on a par with the embedded approach, but it would mean foremost developing an OpenGL application.

For more information see the vlcj-lwjgl-demo project.

The beauty of vlcj's design and architecture means adopting any of these approaches is near identical in usage, only a single video surface abstraction is the difference.

vlcj-5

vlcj-5 is primarily an incremental feature-release, preserving the vlcj-4 API as much as possible.

Major New Features

Headline changes:

  • requires LibVLC 4.0.0+
  • requires Java 8+
  • full support for LibVLC native "video engine" rendering, specifically via OpenGL
  • fast vs precise native seeking when setting media position/time
  • native generation of in-memory thumbnail pictures
  • new native track selection API - this makes it possible to reliably make use of video Sample Aspect Ratio (SAR) when rendering video using the "callback" video players and means e.g. DVD video now can render properly with callback players

For a full list of changes in this release, check the release milestones:

Examples

All of the examples have been moved to the vlcj-examples project.

Known Issues

  • When using the new alternate renderer API, if you attempt to play another media while a media is already being sent to something like Chromecast you may experience problems - even if you stop the current media first. The cause of this is currently unknown, but it may be a native issue.

Tutorials

New tutorials for vlcj-4 are available here.

These tutorials are still valid for vlcj-5.

There are simple tests or demo applications available for pretty much every aspect of vlcj functionality, these are provided in the vlcj-examples project.

There is also a major demo application available at the vlcj-player project page.

Building vlcj - sun.misc.Unsafe

When compiling with Maven it is simply not possible to suppress the warnings about using sun.misc.Unsafe.

Maven Dependency

Add the following Maven dependency to your own project pom.xml:

<dependency>
    <groupId>uk.co.caprica</groupId>
    <artifactId>vlcj</artifactId>
    <version>5.0.0</version>
</dependency>

The core vlcj project now no longer contains the required JNA bindings to LibVLC, these are provided instead by the separate vlcj-natives project. The vlcj core project therefore has a new required dependency on the vlcj-natives project.

If you are using Maven (or similar) to manage your dependencies, the vlcj-natives dependency will be handled automatically for you (you only need to explicitly add vlcj to your project, not vlcj-natives).

If you are installing vlcj manually, then you will need to include the new vlcj-natives jar file along with the existing vlcj jar file.

Threading Model

This section is very important.

With vlcj-4 and later, every native event coming from LibVLC is processed on the native callback thread. This should give some small performance gains when compared with vlcj-3.

The critical issue is that it is generally not permitted to call back into LibVLC from the event callback thread. Doing so may cause subtle failures or outright hard JVM crashes.

A prime example of the sort of trap waiting for you is the very common case of handling a media player "finished" event so that you can then play the next item in a play-list:

mediaPlayer.events().addMediaPlayerEventListener(new MediaPlayerEventAdapter() {
    @Override
    public void finished(MediaPlayer mediaPlayer) {
        mediaPlayer.media().play(nextMrl); // <-- This is VERY BAD INDEED
    }
});

In this example, the finished method is being invoked on a native callback thread owned by LibVLC. The implementation of this method is calling back into LibVLC when it invokes play. This is very likely to cause a JVM crash and kill your application.

In cases such as this, you should make use of an asynchronous task-executor queue conveniently provided by the MediaPlayer object passed to the listener method:

mediaPlayer.events().addMediaPlayerEventListener(new MediaPlayerEventAdapter() {
    @Override
    public void finished(final MediaPlayer mediaPlayer) {
        mediaPlayer.submit(new Runnable() {
            @Override
            public void run() {
                mediaPlayer.media().play(nextMrl);
            }
        });
    }
});

You should not use this mechanism for all of your event handlers, only those that will call back into LibVLC.

Other high-level vlcj components may also provide their own asynchronous task executor, it is not limited to the media player.

An added caveat for vlcj-4 and later is that when you implement event handling you must be sure to execute quickly, and to not block the native thread with any long-running operation.

Your event handler implementations must not throw an Exception, failure of your event handlers to catch and handle any thrown exception may prevent other listeners from being notified of the event.

If you are attempting to use multiple media players in your application, or using media players from multiple threads, you may need to take some extra care so that you do not have multiple threads calling into LibVLC concurrently. You may encounter subtle bugs and races that are very difficult to diagnose.

In addition, you must take care not to update Swing UI components from the native thread - all Swing UI updates are supposed to go via the Swing Event Dispatch Thread (EDT).

You can achieve this in the usual way by using SwingUtilities#invokeLater in your event handler:

mediaPlayer.events().addMediaPlayerEventListener(new MediaPlayerEventAdapter() {
    @Override
    public void finished(MediaPlayer mediaPlayer) {
        SwingUtilities.invokeLater(new Runnable() {
            @Override
            public void run() {
                // ...change UI state here...
            }
        });
    }
});

Garbage Collection

This section is also very important.

Ordinarily when developing with Java you will be used to not thinking about the scope and life-cycle of the objects that you create, instead you will rely on the garbage collector in the Java Virtual Machine to just take care of things for you.

With vlcj's MediaPlayerFactory, MediaPlayer, and associated classes, you must take care to prevent those objects from being garbage collected - if you do not, at best your media player will simply unexpectedly stop working and at worst you may see a fatal JVM crash.

Those vlcj objects wrap a native resource (e.g. a native media player). Those media player resources know nothing about any JVM. So just because a native media player is still "alive" it will not prevent your object instance from being garbage collected. If your object instance does get garbage collected, the native resource still has no idea, and will will keeping sending native events back to the JVM via a callback. If your object is gone, that native callback has nowhere to go and will most likely crash your JVM.

A very common mistake is to declare vlcj objects on the local heap in some sort of initialisation method:

    private void setup() {
        MediaPlayerFactory factory = new MediaPlayerFactory();
        EmbeddedMediaPlayer mediaPlayer = factory.mediaPlayers().newEmbeddedMediaPlayer();
        // ... other initialisation ...
    }

When this method returns, the factory and mediaPlayer objects go out of scope and become eligible for garbage collection. The garbage collection may happen immediately, or some time later.

The most common solution is to change those local heap declarations to class fields:

    private MediaPlayerFactory factory;

    private EmbeddedMediaPlayer mediaPlayer;

    private void setup() {
        factory = new MediaPlayerFactory();
        mediaPlayer = factory.mediaPlayers().newEmbeddedMediaPlayer();
        // ... other initialisation ...
    }

This is fine and will work in most cases, but you must still make sure that the enclosing class does not itself get garbage collected!

See this vlcj garbage collection tutorial for more information.

Privacy Considerations

When parsing media, depending on configuration, it may be possible that a remote network access is made for meta data and album/cover art. This may unintentionally expose sensitive data regarding the media being parsed.

To affirmatively prevent all network access for meta data, consider using the --no-metadata-network-access argument when creating a MediaPlayerFactory.

It should also be possible to prevent such network accesses by using appropriate ParseFlag values when requesting to parse media.

Even with network access disabled, some media cover art may still appear locally (e.g. ~/.cache/vlc) - this does not necessarily mean that a remote network request was made for the cover art, rather the art that was already embedded in the media file was extracted to this temporary cache directory.

In any case, you need to be aware of this issue and inform users of your application about it.

Documentation

The vlcj project page is at github.

Online Javadoc is available here:

Examples

There are many examples in the vlcj-examples project showing how to use vlcj.

For a more complete example of a feature-rich media player built with vlcj, see vlcj-player.

Related Projects

Support

Free support for Open Source and non-commercial projects is generally provided - you can use github issues for this purpose.

Commercial services for vlcj are provided by Caprica Software.

Support for commercial projects is provided exclusively on commercial terms - send an email to the following address for more information:

mark [dot] lee [at] capricasoftware [dot] co [dot] uk

LibVLC Discord

Join the chat at https://discord.gg/3h3K3JF

vlcj is part of the LibVLC Discord Community server. Feel free to come say hi!

License

The vlcj framework is provided under the GPL, version 3 or later.

If you want to consider a commercial license for vlcj that allows you to use and redistribute vlcj without complying with the GPL then send an email to the address below:

mark [dot] lee [at] capricasoftware [dot] co [dot] uk

Contributors

Contributions are welcome and will always be licensed according to the Open Source license terms of the project (currently GPL).

However, for a contribution to be accepted you must agree to transfer any copyright so that your contribution does not impede our ability to provide commercial licenses for vlcj.