Video Thumbnails in Java
Solution 1:
Well, since you're not stuck with JMF, have you considered Xuggler? Xuggler is a Java API that uses FFmpeg under the covers to do all video decoding and encoding. It's free and LGPL licensed.
In fact, we have a tutorial that shows How to Make Thumbnails of an Existing File
Solution 2:
There seems to be a few examples out there that are far better than what I was going to send you.
See http://krishnabhargav.blogspot.com/2008/02/processing-videos-in-java.html.
I'd agree with Stu, however. If you can find a way to get what you want using some command-line tools (and run them using Commons-Exec), you might have a better overall solution than depending on what is essentially the Sanskrit of Java extensions.
Solution 3:
Are you sure that JMF is right for you? Unfortunately, it is not in particularly good shape. Unless you are already committed to JMF, you very well may want to investigate alternatives. Wikipedia has a decent overview at en.wikipedia.org/wiki/Java_Media_Framework
Many JMF developers have complained that it supports few codecs and formats in modern use. Its all-Java version, for example, cannot play MPEG-2, MPEG-4, Windows Media, RealMedia, most QuickTime movies, Flash content newer than Flash 2, and needs a plug-in to play the ubiquitous MP3 format. While the performance packs offer the ability to use the native platform's media library, they're only offered for Linux, Solaris and Windows. Furthermore, Windows-based JMF developers can unwittingly think JMF provides support for more formats than it does, and be surprised when their application is unable to play those formats on other platforms.
Another knock against JMF is Sun's seeming abandonment of it. The API has not been touched since 1999, and the last news item on JMF's home page was posted in November 2004.
While JMF is built for extensibility, there are few such third-party extensions.
Furthermore, editing functionality in JMF is effectively non-existent, which makes a wide range of potential applications impractical.
Solution 4:
My own server-side app shells out to FFmpeg to do the encoding. I'm 98.42% sure FFmpeg does snapshots, too. (It is an all singing, all dancing beast of a program. The command line options alone could fill a book.)
Check it out: ffmpeg.mplayerhq.hu