Re: [rtcweb] Summary of Application Developers' opinions of the current WebRTC API and SDP as a control surface

From: Cullen Jennings <fluffy@iii.ca> · Date: Fri, 19 Jul 2013 07:04:01 -0700

Folks wanted to sort out how mindless works fist before getting to theses smaller details but in general I think progress is being made on all of these

On Jul 17, 2013, at 2:58 PM, "Matthew Kaufman (SKYPE)" <matthew.kaufman@skype.net> wrote:

> Bernard Aboba:
>> 
>> The problem was that we never defined what mangling browsers had to
>> support. Given all the SDP specs that is actually a huge work item.
> 
> 
> This is exactly what my slides that weren't presented last November started to touch upon. It only takes a few minutes with RFC3264 and its references to start documenting cases that are clearly "valid SDP offer/answer" and yet for which I cannot for the life of me figure out what a browser should do if they're presented.
> 
> Just off the top of my head:
> 
> Can I...
> - Change the t= line to be something other than t=0 0?
> - Change the rtpmap associations before calling setLocal?
> - Change a=sendrecv to a=recvonly before calling setLocal?
> - What do you do when you see a=content:sl ?
> - What if someone adds an r= or p= or e=?
> - What is the RFC that describes a=group:BUNDLE (as seen in some browser implementations)?
> - Can I remove a=group:BUNDLE (or add it) before calling setLocal?
> - How about removing a=rtcp-mux?
> - Should I do something special at my end if you set a=ice-options:google-ice ?
> - If you put a=ssrc lines in there, can I change the ssrc before passing it back to setLocal?
> - Can I delete the a=ssrc lines?
> - Is a=rtcp:1 IN IP4 0.0.0.0 valid or not?
> - What about 0.0.0.0 in the o= line?
> - If I get a bunch of a=candidate lines, can I swap them around to change the priority before calling setLocal?
> - What if someone claims SAVP instead of SAVPF but gives me rtcp info?
>    
> At the *very least* for each and every line that comes from createOffer and createAnswer you must be able to answer the following:
> - Can I delete it?
> - Duplicate it?
> - Change it?
> - If not, how are violation handled? (Both when passed to another browser at the far end and when these modifications happen before calling setLocal)
> - And can I add additional valid SDP to what came from createOffer or createAnswer and pass it back to setLocal or not?
> 
> We appear to be nowhere near a document which explains the answers to these questions, certainly not in the W3C WG, and not in any IETF RFC or draft I can locate.
> 
> Matthew Kaufman
> 
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