Re: [AVTCORE] I-D Action: draft-ietf-payload-vp9-11.txt

Do you know what the browsers will do if they change in a subsequent offer, whether due to SDP munging or a non-browser peer?  Or if they’re received in an answer which doesn’t match the offer?

> On Feb 4, 2021, at 11:33 AM, Bernard Aboba <bernard.aboba@gmail.com> wrote:
> 
> Jonathan said: 
> 
> "Hm.  For these, I think the best thing to do would be to see how the existing (browser) implementations handle these, since there’s deployed code here.  Justin, would you be able to ask inside Google?  And since as I understand it the SDP parsing code is separate for the different browsers, is there someone at the other browser implementations who could check those as well?"
> 
> [BA] Since there is no WebRTC API to set maxfs/maxfr, the values emitted in subsequent Offers won't change. 
> 
> On Thu, Feb 4, 2021 at 8:26 AM Jonathan Lennox <jonathan.lennox@8x8.com <mailto:jonathan.lennox@8x8.com>> wrote:
> 
> Hi, Christer - thanks for your comments.
> 
> > On Feb 2, 2021, at 2:30 PM, Christer Holmberg <christer.holmberg@ericsson.com <mailto:christer.holmberg@ericsson.com>> wrote:
> > 
> > Hi,
> > 
> > I don't know if the document will be sent to the SDP directorate, so I will give a few comments here:
> > 
> > Q1:
> > 
> > In Section 6.2.1.1., please place the m= lines and each attribute on separate lines.
> 
> Apologies, this was an xml2rfc formatting error.  I’ll fix it for the next version.
> 
> > Q3:
> > 
> > Is there a reason why profile-id is optional, since a value will always be assumed?
> 
> Since profile-id negotiation was developed relatively late in the process of writing the spec, existing implementations don’t always send it.  It seemed best to maintain compatibility here.
> 
> > Q2:
> > 
> > In Section 6.2.1, my understanding is that max-fs and max-fr are optional. Section 6.2.2 says that the answerer must maintain all configuration parameters. Does that apply to max-fs and max-fr too? If so, if the offer does not contain max-fs and max-fr, the answer cannot contain them either?
> 
> > Q4:
> > 
> > Section 6.2.2. does not define any restrictions on what can be modified in a subsequent offer, so I guess one can modify max-fs, max-fr and/or profile-id in a subsequent offer?
> 
> Hm.  For these, I think the best thing to do would be to see how the existing (browser) implementations handle these, since there’s deployed code here.  Justin, would you be able to ask inside Google?  And since as I understand it the SDP parsing code is separate for the different browsers, is there someone at the other browser implementations who could check those as well?
> 
> Thanks!
> 
> Jonathan
> 
> _______________________________________________
> Audio/Video Transport Core Maintenance
> avt@ietf.org <mailto:avt@ietf.org>
> https://www.ietf.org/mailman/listinfo/avt <https://www.ietf.org/mailman/listinfo/avt>