SDP Response Example

Transcript

[slide196] And then the other party can respond and say okay, I can accept this kind of video or I can decline the video by the port number to 0. I can say I'm not interested in PCM encoded audio but I can take the GSM encoded audio and here is the sample rate I want you to use. So the other party sends them the requested media. So one side is saying here are the things I'm capable of. The other party says of those things you're capable of, here are the ones I'm interested in. We're set. We hope it's a non-null overlap. So if you reject all of the things the other party said they could talk, you can't have a session. So what would you have to do? You'd have to start all over again and hope they announce a new set of opportunities for you to choose what you want. Why is it the sender that's deciding what it is that they're offering? And the receiver what they want, what they will accept. [student answers: The receiver has to decide what they can play out.] The receiver has to do the play out. [student answers: It depends on the features of the CODEC what it can playout.] That's right. So the receiver has to say, I can actually manage to decode the following types of CODECs. But why does the sender have to make the offer in the first place? [student answers - not audible] Yes. If we're going to send it to them for them to play it out in a particular CODEC, we had better have the CODEC to be able to encode it, otherwise, we'd be in trouble. So that's why we don't start it the other way with the receiver saying, hey, here are all the things I can accept, We let the sender say here are all of the things I can generate, and then the receiver says, out of those, these are the ones I can decode.