[Libav-user] adding digital watermark to mpeg4 video

[Igor R]

Hello,

In my project I get mpeg4 video stream from a network (proprietary
protocol) and mux it into some container (say avi).
Now we'd like to put a protecting "watermark" on this stream. Just to
clarify: I don't mean a semi-transparent text over the video, but a
digital signature of the stream, which would verify its authenticity.
I know MS WMV format supports such a feature through special
watermarking DMOs, but as for standard mpeg4 video streams in standard
containers (avi, mp4 etc) - I haven't managed to find sufficient
information.
So I've got several questions: 1) Is it theoretically possible to add
such a signature to mpeg4 video - either in avi or any other
container? 2) Is it possible with libav* (with or without recoding the
original stream)? If yes, what APIs should I look at? 3) If I already
have a signature, is it possible somehow to store it along with the
stream, as a metadata?

Thanks.