Subject: [rtcweb] JSEP: Imageattr and CVO

From: Magnus Westerlund <[email-masked]>
Date: Mon, 22 Jun 2015 11:34:46 +0200

Hi,

I got an action point at the interim to check on what 3GPP and GSMA says 
about their usage of a=imageattr and CVO (Coordination of Video 
Orientation).

3GPP SA4 in TS 26.114 (Which defines CVO) there is discussion about the 
usage of a=imageattr when a endpoint is not CVO capable, but it appears 
to fail to be explicit about interpretation of imageattr when using CVO. 
As the text says that for a non CVO capable endpoint one have to express 
both orientations (x,y) and (y,x) in imageattr and perform the rotation 
prior to encoding.

This appear to support the proposed interpretation for JSEP, i.e. that 
one expresses the supported max resolution without rotation using 
imageattr.

Bo Burman intend to prepare an contribution to 3GPP SA4 in their 
upcoming meeting in two weeks time and see if SA4 can come to agreement 
on this interpretation and write it into their specifications. So in 
time for Prague we will hopefully be able to conclude on this.

Cheers

Magnus Westerlund

----------------------------------------------------------------------
Services, Media and Network features, Ericsson Research EAB/TXM
----------------------------------------------------------------------
Ericsson AB                 | Phone  +46 10 7148287
Färögatan 6                 | Mobile +46 73 0949079
SE-164 80 Stockholm, Sweden | mailto: [email-masked]
----------------------------------------------------------------------

---

From: Justin Uberti <[email-masked]>
Date: Wed, 24 Jun 2015 04:28:31 +0000

Great. Thanks for tracking this down.