Multishow
Multishow is a multipurpose file viewer for audio, video, images and text. It a multiplatform Java application. MultiShow supports examining files at multiple levels of abstraction. From the home page "The high level views show a file as audio, video, image or text. The intermediate level views show the logical structure of the file content. At the lowest level, a binary or textual representation of the file is shown."
multishow is available under a fairly liberal licence. It contains a non-commercial clause which makes it gpl incompatible, but the author Werner Randelshofer is friendly towards the ffmpeg project so if you ask him nicely, he might relicence parts of the code to (ffmpeg compatible) gpl/lgpl if you ask nicely. multishow licence