Subject: [Slim] I-D Action: draft-hellstrom-slim-simultaneous-modalities-00.txt

From: Gunnar Hellström <[email-masked]>
Date: Wed, 7 Jun 2017 13:36:22 +0200

An initial draft for identifying simultaneous modalities in real-time 
communication is available.

I would like to get acceptance of the draft as a working group draft.

Regards
Gunnar

A New Internet-Draft is available from the on-line Internet-Drafts 
directories.

         Title           : Negotiating Simultaneous Modalities  in 
Real-Time Communications
         Author          : Gunnar Hellstrom
	Filename        : draft-hellstrom-slim-simultaneous-modalities-00.txt
	Pages           : 6
	Date            : 2017-06-07

Abstract:
    In a real-time communication session, there may be a need or
    preference for receiving the same content in two or more simultaneous
    modalities.  This specification extends a mechanism for human
    language negotiation with a mechanism for indication of preference
    for, or the availability of, simultaneously provided transformations
    of original contents.  This indication enables negotiation of
    simultaneous modalities in real-time sessions.  Applications are for
    example provision of both spoken and written content in a real-time
    call (captioning), or provision of both spoken language original and
    sign language interpretation of the original language in a real-time
    session.

The IETF datatracker status page for this draft is:
https://datatracker.ietf.org/doc/draft-hellstrom-slim-simultaneous-modalities/

There are also htmlized versions available at:
https://tools.ietf.org/html/draft-hellstrom-slim-simultaneous-modalities-00
https://datatracker.ietf.org/doc/html/draft-hellstrom-slim-simultaneous-modalities-00

Please note that it may take a couple of minutes from the time of submission
until the htmlized version and diff are available at tools.ietf.org.

Internet-Drafts are also available by anonymous FTP at:
ftp://ftp.ietf.org/internet-drafts/

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---

From: Paul Kyzivat <[email-masked]>
Date: Wed, 7 Jun 2017 15:43:23 -0400

I did a quick review of these documents. My feeling is that these have 
moved to quickly to specific solution syntax without first sorting out 
exactly what the needs are. I am sympathetic to what I think the goals 
are, but am concerned that the proposed solutions are not ideal.

For instance, simultaneous-modalities indicates the languages of the 
source form and the transformed form. But it does not indicate precisely 
which media stream contains the source form. I guess the assumption is 
that there will only be one other media stream with the appropriate 
language indication. But that is just an assumption. It may well apply 
in a number of common cases, but I'm sure we can come up with more 
complex cases where that isn't true. ISTM that it would be better to 
come up with a syntax that explicitly links the source and transformed 
media streams. (E.g. a new usage of the grouping framework.)

In the modalitypref document if find the semantics fuzzy, and the 
relationship of the use of "*" for this to be even more fuzzy when 
related to its use in draft-ietf-slim-negotiating-human-language. For 
instance, I see a potential conflict between need to express degree of 
competence with a modality with preference for that modality. It may be 
that those should be handles as two distinct indicators. Further 
discussion is needed.

	Thanks,
	Paul

---

From: Gunnar Hellström <[email-masked]>
Date: Wed, 7 Jun 2017 22:44:32 +0200

Paul,  thanks for reviewing and commenting,

> are, but am concerned that the proposed solutions are not ideal.
<GH>During the lengthy discussions about the functionality that these 
two drafts add to the human-language-negotiation draft, low complexity 
has always been a strong argument for keeping notation very simple and 
rather make functionality shortcuts than allow parameters that add 
complexity. That explains why the proposals look as they do, but of 
course decisions can be made to change this approach.
> source form and the transformed form. But it does not indicate 
> precisely which media stream contains the source form. I guess the 
> assumption is that there will only be one other media stream with the 
> appropriate language indication. But that is just an assumption. It 
> may well apply in a number of common cases, but I'm sure we can come 
> up with more complex cases where that isn't true.
<GH>I think it will be straightforward to find the original. It must be 
in another media than the one with the "t" extension, because the 
human-language-negotiation draft does not allow more than one language 
negotiated per stream. If the original is a sign language, then it is to 
be found in the video stream. If it is not a sign language the original 
is to be searched in the audio specification if the "t"-extended 
language is in a written media and the opposite.  Only if we start using 
more than one media stream per media we get more complications to find 
the original. But it is still doable and we have not at all discussed 
multiple streams of the same media kind for our base draft.
> ISTM that it would be better to come up with a syntax that explicitly 
> links the source and transformed media streams. (E.g. a new usage of 
> the grouping framework.)
<GH>We have discussed the use of the grouping framework a long time ago, 
and it was not a popular solution because of the complexity it causes.

An alternative I have proposed is q-values with the extra rule that 
q-values less than 0.1 apart implies request for simultaneous 
languages/modality. But q-values have been rejected.
> competence with a modality with preference for that modality. It may 
> be that those should be handles as two distinct indicators. Further 
> discussion is needed.
<GH>I think it is often the degree of competence that causes the grade 
of preference. But sometimes it may be the
feasability of using a modality in the conversational setting, e.g. a 
noisy place.
The current coding with the * makes a shortcut in that all languages 
specified for that media gets the same preference. So the following 
reasoning cannot be coded: "I can use spoken English well, but my French 
is so bad that I prefer to use that in written modality" .
I think the preference put on the modality rather than on language level 
is a good and realistic simplification.  I agree that the co-use of the 
asterisk with the preference for non-denial of the session is not 
elegant. But its effects are mild and described in the 
modality-preference draft.

Alternatives are q-values with scope over the whole SDP or separate 
a=modalitypreference:HI  attributes.  Q-value proposals have been rejected.

Thanks,
Gunnar
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-- 
-----------------------------------------
Gunnar Hellström
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---

From: Paul Kyzivat <[email-masked]>
Date: Wed, 7 Jun 2017 17:50:22 -0400

> multiple streams of the same media kind for our base draft.

AFAIK we have not discussed it because there has been no need to. Not 
discussing doesn't mean that such usage has been excluded or that it 
needs more consideration before it can be used.

But once we start linking two streams together then it gets important. 
Leaving it to ad hoc implementation without specification is asking for 
trouble.

> and it was not a popular solution because of the complexity it causes.

I only threw that out as one possibility. But it directly fits the use 
case, and whatever complexity it brings is mitigated because it is an 
existing mechanism.

> languages/modality. But q-values have been rejected.

That addresses an entirely different problem.

> a=modalitypreference:HI  attributes.  Q-value proposals have been rejected.

ISTM that the rejections were because these were perceived as making the 
base mechanism more complex. Once this is split off as a separate 
mechanism then I think we get to revisit those discussions.

	Thanks,
	Paul