// AACTrackImpl aacTrack = new AACTrackImpl(Ac3Example.class.getResourceAsStream("/sample.aac"));
AACTrackImpl aacTrack = new AACTrackImpl(new FileInputStream("/Users/magnus/Projects/castlabs/cff/Solekai015_1920_29_75x75_v2/Solekai_BeautifulTension_15sec_160k.aac"));
Movie m = new Movie();
m.addTrack(aacTrack);
DefaultMp4Builder mp4Builder = new DefaultMp4Builder();
IsoFile isoFile = mp4Builder.build(m);
FileOutputStream fos = new FileOutputStream("output.mp4");
isoFile.getBox(fos.getChannel());
fos.close();