I have reviewed this document as part of the security directorate's ongoing effort to review all IETF documents being processed by the IESG. Document editors and WG chairs should treat these comments just like any other last call comments. This draft defines a way to ask a sender to use different image attributes using SDP. The security considerations says that this doesn't change anything, but I don't quite agree. A requestor could (accidentally or on purpose) as for some very large image size or for some kind of transformation that puts a lot of load on a transcoder, and that could be part of some DoS attack. (I've actually seen this bug triggered accidentally in a real system that did more or less this.) I'd suggest adding a paragraph to the security considerations saying that implementations should be wary of this and could include some sanity checking of inputs or could try to detect cases where lots of resources are being used and then handle that somehow. I don't know how that'd be best done, nor whether any of that should use 2119 type language, but I assume the authors can figure that out. Stephen.