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Re: [tsvwg] Last Call: <draft-ietf-tsvwg-rtcweb-qos-15.txt> (DSCP and other packet markings for WebRTC QoS) to Proposed Standard
2016-05-03 11:59:22
On Tue, May 3, 2016 at 9:38 AM, Black, David
<david(_dot_)black(_at_)emc(_dot_)com> wrote:
Ted,
Thanks for expressing concerns ... I have an alternative suggestion:
I'm not so happy adding a description of where other media travels.
Thinking out loud - what if we put the text to cover both interactive
media usage
of RTP and non-interactive media usage of something else into the Web RTC
transports
draft (https://datatracker.ietf.org/doc/draft-ietf-rtcweb-transports/)?
That draft has the requisite broader scope, and it’s even not at the RFC
Editor(!).
I'm not so happy adding a description of where other media travels.
That's going
to be app-specific, and since saying "we don't know this" in the
document does not
help implementers, I'd personally rather leave it out.
Would it be reasonable (in the transports draft) to say that
- interactive video uses RTP and
- non-interactive video does not use RTP?
I think that's likely to work. If it doesn't, because there are apps which
are planning to use
RTP for game fill media or similar, then we need an API surface to indicate
the different uses.
That solves the problem in a more general way.
regards,
Ｔed
That’s close to the minimum language that’s needed to close out the
original issue
in this draft (tsvwg-rtcweb-qos), namely that implementers need a clearly
specified
means of determining whether video is interactive vs. non-interactive.
Thanks, --David
*From:* Ted Hardie [mailto:ted(_dot_)ietf(_at_)gmail(_dot_)com]
*Sent:* Tuesday, May 03, 2016 11:20 AM
*To:* Black, David
*Cc:* Paul E. Jones; Magnus Westerlund; Cullen Jennings;
tsvwg(_at_)ietf(_dot_)org;
draft-ietf-tsvwg-rtcweb-qos(_at_)ietf(_dot_)org; ietf(_at_)ietf(_dot_)org;
tsvwg-chairs(_at_)ietf(_dot_)org
*Subject:* Re: [tsvwg] Last Call: <draft-ietf-tsvwg-rtcweb-qos-15.txt>
(DSCP and other packet markings for WebRTC QoS) to Proposed Standard
On Tue, May 3, 2016 at 8:29 AM, Black, David
<david(_dot_)black(_at_)emc(_dot_)com> wrote:
Paul,
Cullen - would you be amenable to drafting a blunt RFC Editor note
for the RTP usage draft to state that all current Web RTC RTP usage is
for interactive media,
If you stop here, I personally think it is fine.
and non-interactive Web RTC media flows currently
use HTTP (and would that be HTTP over the Web RTC data channel or
something else)?
I'm not so happy adding a description of where other media travels.
That's going to be
app-specific, and since saying "we don't know this" in the document does
not help
implementers, I'd personally rather leave it out.
Obviously, the rtcweb WG will have to sign off on that RFC Editor note,
but this looks like a relatively short path to addressing the problem.
Do you want to summarize the issue to the wg now, or wait until there is a
candidate RFC editor note?
Ted
Thanks, --David (as draft shepherd)
-----Original Message-----
From: Paul E. Jones [mailto:paulej(_at_)packetizer(_dot_)com]
Sent: Monday, May 02, 2016 10:18 PM
To: Magnus Westerlund; Black, David; Cullen Jennings
Cc: ietf(_at_)ietf(_dot_)org; tsvwg-chairs(_at_)ietf(_dot_)org;
draft-ietf-tsvwg-rtcweb-qos(_at_)ietf(_dot_)org;
tsvwg(_at_)ietf(_dot_)org
Subject: Re: [tsvwg] Last Call: <draft-ietf-tsvwg-rtcweb-qos-15.txt>
(DSCP and
other packet markings for WebRTC QoS) to Proposed Standard
As I understand, we need this addition:
Currently in WebRTC, media sent over RTP is assumed to be
interactive <xref target="I-D.ietf-rtcweb-rtp-usage"/>
while media streamed over HTTP <xref target="RFC7230"/>
<xref target="RFC7540"/> is assumed not to be. Future WebRTC
extensions could allow streamed, non-interactive media over RTP.
I modified is slightly by adding "non-interactive" near the end and
inserting a reference near "interactive", though this is perhaps a
redundant reference since it appears elsewhere in the draft.
That RTP usage reference does not speak to HTTP, so I don't have a
reference to "prove" that sentence above. Is there a better reference?
Paul
------ Original Message ------
From: "Magnus Westerlund" <magnus(_dot_)westerlund(_at_)ericsson(_dot_)com>
To: "Black, David" <david(_dot_)black(_at_)emc(_dot_)com>; "Cullen Jennings"
<fluffy(_at_)iii(_dot_)ca>
Cc: "ietf(_at_)ietf(_dot_)org" <ietf(_at_)ietf(_dot_)org>;
"tsvwg-chairs(_at_)ietf(_dot_)org"
<tsvwg-chairs(_at_)ietf(_dot_)org>;
"draft-ietf-tsvwg-rtcweb-qos(_at_)ietf(_dot_)org"
<draft-ietf-tsvwg-rtcweb-qos(_at_)ietf(_dot_)org>;
"tsvwg(_at_)ietf(_dot_)org"
<tsvwg(_at_)ietf(_dot_)org>
Sent: 4/19/2016 4:46:53 AM
Subject: Re: [tsvwg] Last Call: <draft-ietf-tsvwg-rtcweb-qos-15.txt>
(DSCP and other packet markings for WebRTC QoS) to Proposed Standard
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(_at_)iii(_dot_)ca]
Sent: Friday, April 15, 2016 10:48 AM
To: Black, David
Cc: Magnus Westerlund; ietf(_at_)ietf(_dot_)org;
tsvwg-chairs(_at_)ietf(_dot_)org;
draft-ietf-tsvwg-
rtcweb-qos(_at_)ietf(_dot_)org; tsvwg(_at_)ietf(_dot_)org
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(_dot_)black(_at_)emc(_dot_)com>
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
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