Comment Re:So, its for the DRM then... (Score 1) 436
Often the DRM does need to know about the stream it is encoding though. Because it will only encode part of the stream. This is true of DVDs for instance. If you let mplayer play an encoded DVD stream you will see fragments of frames. I bet the same if true of modern DRM. It uses up space to encrypt. So you just encrypt enough to make the stream unwatchable (like only only encrypt the key frames). And to do that you need to know the structure of the stream and implementing that for multiple different stream type requires being not lazy.