> On 6 Oct 2016, at 18:48, Dale R. Worley <wor...@ariadne.com> wrote: > > Sachin Rastogi <sachin.0.rast...@gmail.com> writes: >> I have a User Agent, which can decode H.264-HP as well as H.264-BP. But it >> can encode only H.264 BP. So how should I share my offer in SDP > > Clearly, you can only express this in SDP by providing two different > m-lines, one for the send codec and one for the receive codecs. (Which > you could bundle.) The problem that I see is that very few devices will > be prepared to split sending and receiving of a video channel on > different m-lines, they will be looking for one sendrecv m-line that > they find acceptable.
Indeed; I’ve never met any SIP device that would handle two video m-lines like that. Although it’s a bit laborious, probably the most compatible way of doing this is to offer both HP and BP in a single sendrecv m-line. If the far end supports BP, you’re all good, and can send BP to them, and they could choose to send HP to you if they want. The only problem would occur if the far end offered only HP. At that point, you should re-INVITE without HP support, and see what happens - the far end may at that point decide it supports BP after all, or it may zero port it if it doesn’t support BP at all. Which is probably the result you’d expect. If one-way video was acceptable, you could re-INVITE again as sendonly HP, but that would seem a very niche case. Incidentally, HP can decode CB, so if you can encode as CB you could send that if the far end claimed to only support HP. Regards, Alan _______________________________________________ Sip-implementors mailing list Sip-implementors@lists.cs.columbia.edu https://lists.cs.columbia.edu/mailman/listinfo/sip-implementors
