Are there any open source java libraries that can be used on desktop systems for mixing and converting two sound files(mp3/mp4 audio with 3gp/.caf) and producing a resultant compilation in say .3gp format?
Also, is there any java library for desktop systems that can convert an audio in .3gp format to a video format? Also, when converting to video we would be specifying an image resource which is to be displayed all the time video is playing.
There is a muziic encoder tool which does something similar.
Check if Xuggler will meet your needs.
I'm not knowledgeable about AV formats, but I've successfully used this to convert from one video format to another. It's just a JNI bridge to the ffmpeg suite, so if ffmpeg can do what you want, most likely Xuggler can too.