Den 2016-04-18 kl. 15:04, skrev Black, David:
So, summarizing Magnus's concerns with proposals:
[1] Flow Type in application-facing browser API:
Propose an additional sentence:
OLD
o Flow Type: The browser provides this input as it knows if the flow
is audio, interactive video with or without audio, non-interactive
video with or without audio, or data.
NEW
o Flow Type: The browser provides this input as it knows if the flow
is audio, interactive video with or without audio, non-interactive
video with or without audio, or data. For audio that is associated
with a video flow, the flow type of the associated video MAY
be used instead of the associated audio type.
Magnus - does that new text suffice?
Yes.
[2] What does "interactive" mean in an implementation?:
We could add something along lines of ..... Currently in WebRTC, media sent over
RTP is assumed to be interactive while media streamed over HTTP is assumed not
to be. Future WebRTC extensions could allow streamed media over RTP.
I believe the proposed additional sentence addresses the question of how a browser
determines whether a video flow is interactive. This proposed sentence will need to
cite a WebRTC document that contains a statement to that effect, as I don't think this
draft is the right place to be the primary reference for that statement.
Magnus - would this approach be ok?
Yes.
/Magnus
Thanks, --David
-----Original Message-----
From: Cullen Jennings [mailto:fluffy@xxxxxx]
Sent: Friday, April 15, 2016 10:48 AM
To: Black, David
Cc: Magnus Westerlund; ietf@xxxxxxxx; tsvwg-chairs@xxxxxxxx; draft-ietf-tsvwg-
rtcweb-qos@xxxxxxxx; tsvwg@xxxxxxxx
Subject: Re: [tsvwg] Last Call: <draft-ietf-tsvwg-rtcweb-qos-15.txt> (DSCP and
other packet markings for WebRTC QoS) to Proposed Standard
On Apr 3, 2016, at 3:37 PM, Black, David <david.black@xxxxxxx> wrote:
I see a couple of Magnus's points that appear to need additional text
in the draft:
[1] Flow Type in application-facing browser API:
o Flow Type: The browser provides this input as it knows if
the flow is audio, interactive video with or without audio,
non-interactive video with or without audio, or data.
[... snip ...]
The main issue here is that to me it was not clear that "Interactive
Video with or without audio" allows for setting these DSCP values also
for the RTP stream containing audio also. This, I do see a need for
clarification on.
Propose an additional sentence:
OLD
o Flow Type: The browser provides this input as it knows if the flow
is audio, interactive video with or without audio, non-interactive
video with or without audio, or data.
NEW
o Flow Type: The browser provides this input as it knows if the flow
is audio, interactive video with or without audio, non-interactive
video with or without audio, or data. For audio that is associated
with a video flow, the flow type of the associated video MAY
be used instead of the associated audio type.
I hesitate to say anything stronger than "MAY" here.
Looks good.
[2] What does "interactive" mean in an implementation?:
We could add something along lines of ..... Currently in WebRTC, media sent over
RTP is assumed to be interactive while media streamed over HTTP is assumed not
to be. Future WebRTC extensions could allow streamed media over RTP.
The issue is that this document is called: DSCP and other packet
markings for WebRTC QoS. Then this document define something that is not
immediately mappable onto what is being defined in the other WebRTC
specifications. That is why I am raising that there need to be more
clear coupling. If that coupling is to mostly happen in another
document, can we at least then have a proposal on the table for that
change to ensure that the result is understandable.
Well, this TSVWG draft is definitely not the right place for a discussion of
when a video flow is interactive or non-interactive - I hope we can agree
on that.
Beyond that, as Cullen (Jennings) is both an author of this document and
one of the chairs of the rtcweb WG, I'd suggest that he and/or the rtcweb
WG propose an appropriate location for discussion of when a video flow
is interactive or non-interactive. This TSVWG draft would then have an
additional sentence added, e.g.,
See [TBD] for further discussion of how to determine
whether a video flow is interactive vs. non-interactive.
I believe that the added reference here ([TBD] above) would be normative.
Cullen?
That discussion happened long ago for WebRTC and we decided we did not need
a JavaScript controls point in the WebRTC API to indicate if RTP was interactive or
not. If people start doing streaming video over RTP we can come back and revisit
this and trivially add an API to indicate that in the W3C WebRTC API. Part of what
drove this decision is the likes of Netflix / ITunes / Youtube are not asking the
browser vendors for streaming media over RTSP or RTP. They think HTTP works
much better for this. Thus the browser vendors see no need for non interactive
video over RTP. I agree with Magnus that this might change some day in the
future but right now, I think it's close enough that everyone can live with it.
I'm not OK in treating it like some open issue that is still in discussion that
somehow holds up this spec - it's not.
Thanks, --David (as document shepherd)
--
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: magnus.westerlund@xxxxxxxxxxxx
----------------------------------------------------------------------