Is it possible to legally progressive play Windows Media DRM tracks as they are downloaded from a HTTP link?
I've managed to do this without DRM but someone here told me it wasn't possible with DRM. Is this true?
And if so with what set of libraries or technologies?
I'm pretty sure it's possible and not illegal either. Normally, information about content encryption and actual encrypted content is kept separate in the same container. That is to say, metadata is not encrypted but content is. To support progressive download, the content is normally encrypted i small transferable ordered chunks. Your DRM client uses the metadata to locate a license server, next a license and content key is acquired from the license server. Next, your client downloads the content "chunk-per-chunk" ,decrypts each chunk, and renders it as a motion picture while it is downloading.
For information on SDK's, check out the different components here.