Re: [rtcweb] JSEP and video stream properties selection (a=imageattr usage)

[Harald Alvestrand <[e-mail]>]

On 09/20/2013 08:02 AM, Magnus Westerlund wrote:
> WG,
>
> In the JSEP call I commented regarding a=imageattr open issue that we
> had an original agreement from over a year ago (Vancouver) to go with
> Harald's proposal in then
> http://tools.ietf.org/id/draft-alvestrand-rtcweb-resolution-00.txt
>
> This is documented in the minutes:
> http://www.ietf.org/proceedings/84/minutes/minutes-84-rtcweb
>
>
> However, I did forget to note that there has been discussion on this
> issue after that between Harald Alvestrand and Stefan Håkansson
> primarily on the W3C list
>
> http://lists.w3.org/Archives/Public/public-webrtc/2013Aug/0051.html
>
> Where they are seriously discussing only using WebRTC API for this.
>
> It is in the context of
> https://datatracker.ietf.org/doc/draft-alvestrand-constraints-resolution/
>
> Thus I would like to point out that there appear to be some indication
> of desire move away from the consensus last year.

My thinking is that there are 3 points on the spectrum of solutions:

- Constraints at source only (the approach most thoroughly described in
draft-alvestrand-constraints-resolution).

- Constraints at destination can be sigalled in SDP, and acted on at
source (described in draft-alvestrand-rtcweb-resolution). This spec
could not be pursued as long as the "Plan X" discussions were still
unsettled, but now it should really be "a piece of cake".

- Defining a new way of signalling. This was the approach rejected in
Vancouver.

Formalistically, if the IETF decides to offer a well defined mechanism
for negotiating resolution through SDP, the W3C will certainly take up
the discussion on whether or not we should connect the API to that
functionality.

Happy to discuss more.