December 2nd, 2008

Extended support for native video codecs in JMC

There’s nothing like the right link at the right time. Remy Rakic (Twitter alias lqd) has left a link to the apparent release jars of JavaFX Desktop 1.0 in the comments on the previous entry. So i’ve decided to see whether there is anything new in the JMC department since the last time i’ve looked at it.

In the JavaFX preview, the native code was shipped directly in the jmc.dll. The download folder has the native libraries available in three platform-specific jar files (one for Windows, Mac OS X and Linux each). For Windows, the jar contains four DLLs:

  • jmc.dll as before
  • on2_decoder.dll which would be presumably responsible for the new licensed decoders
  • msvcp71.dll and msvcr71.dll which are parts of Visual C++ 7.1

Assuming that this download folder is going to be used as a centralized WebStart repository, i would venture to say that there is going to be some kind of built-in mechanism for extracting these DLLs at runtime and updating the java library path. However, in my experiments i had to extract them manually and point the -Djava.library.path to the folder that contains those DLLs. We’ll wait and see whether the final (and official) release will follow in the footsteps of SWT 3.3 that handles the locally run extraction automatically.

Apart from the new JMediaView class that is a lightweight Swing component I haven’t seen any new classes. However, this JMC drop can play all QuickTime content from the sample page, including H.264, MPEG-4, 3GPP and MPEG-2, as well as the full scale trailers from the Apple site (in H.264 format). The playback support goes a long way towards my number one wish for desktop Java in 2008, and it will be hopefully followed by the recording capabilities as well.

I’ve decided to dive a little bit deeper into the JMC internals and updated the JMCFrame class to show a skeleton implementation of a “home-grown” player. Instead of using ready-made classes such as JMediaPlayer, JMediaPane or JMediaView, i’m creating a MediaProvider from the specific URI and attaching a VideoRendererListener to its VideoRenderControl (i would guess that the JMedia* classes follow the same route, but without the source code it’s hard to tell). This certainly makes the code a little bit more complicated, but allows much greater flexibility as far as compositing and overlaying go. Here is a screenshot of the player in action:

What do you see in the screenshot? There is a JPanel with a JButton control in it. The JPanel overrides the paintComponent and paints the following three layers:

  • Gradient checkered background.
  • The contents of the current video frame with 80% opacity.
  • Information on the current media location, total duration and rate.

Using a MediaProvider with a VideoRendererListener allows some interesting things – overlaying translucent controls and HUDs, cross fading between multiple video streams and rendering video streams on arbitrary Swing components.

The new implementation supports dropping two kinds of video content:

  • Local file
  • URL

If you run the sample code locally, drag a local video file on the panel and press the play button. The content should start playing. You can also drag a URL from your favourite browser. If that URL points to a video stream, the stream will be played – tested on streaming H.264 movie trailers from the Apple site :)

If i had to choose a particularly nifty API, that would be the MediaControl in the com.sun.media.jmc.control package. To get the specific control, call MediaProvider.getControl passing the class instance of the required control (such as VideoRenderControl). The MediaProvider.getControls API will enumerate the supported controls. Here is what i see on my machine when playing video files: play, audio, video, subtitle, video render and track. Hopefully we are going to see the record control joining this group soon.