Re: [MMUSIC] comments on draft-holmberg-mmusic-sdp-mmt-negotiation-00

[Christer Holmberg <[e-mail]>]

Hi Charles,
 
>I read the draft, and I have some concerns it with. It seems that in general one needs to duplicate much of the information from each individual media description in the anymedia media description. I think I could live with that; 
>however, the bigger problem is in regard to figuring out what needs to be specified in the anymedia media description. In the good cases, you merely duplicate the SDP attributes from each individual media description in the anymedia 
>media description. In the bad case, you need to define new SDP attributes.
>Here are some related comments in regard to specific section of the existing draft.
>
>1) Section 5.2.2.2 seems to imply that accepting/rejecting an anymedia media description is always an all of nothing matter. If it contains 2 audio lines and 2 video lines, I need to accept all of them or none of them. It that is the 
>intent, it seems pretty limiting to me.

That is not the intent.

However, it is related to a more general (not specific to muliplexing) question that needs to be clarified - how individual sources/streams within an SDP m- line are rejected.

>2) Section 6.3 says directionality of anymedia applies to all media lines. This seems limiting as well. I may want to temporarily stop a video stream (i.e. make inactive or recvonly), but continue to have the audio be sendrecv.

You can use the ssrc attribute to set the directionality for individual sources/streams.

>3) Section 6.4, I think you need to be able to specify the bandwidth for each media stream in the anymedia group, so new syntax will be needed to deal with the bandwidth attribute.

Yes.

But, again, it is a generic thing for when you have multiple sources/streams per m- line.


Regards,

Christer