Re: [Slim] Open Issue #26 on draft-ietf-slim-negotiating-human-language and also #27, #34 and #39

[Gunnar Hellström <[e-mail]>]

Issue #26 started as a discussion of functionality extensions. That 
topic also relate to issues #34 and #39. Because the coding depends on 
the selection of resolution on these issues.

Bernard also brought up the need for coding of indications of captioning 
that is simultaneous use of languages in 
https://www.ietf.org/mail-archive/web/slim/current/msg00730.html. It 
could have been assigned a separate issue but I include discussion of 
that need here.

When resolving the current list of issues with 
draft-ietf-slim-negotiating-human-language we need to see how the two 
discussed functionlity extensions can be coded. The extensions are: a) 
relative preference between languages in different media and the same 
direction, and b) indication of simultaneous versus alternative use of 
languages in the same direction.

This is an overview of possible solutions to the functionality 
extensions and how they depend on the selected solutions of the issues. 
I have submitted similar proposals before, but this proposal is further 
limited to the two most suitable proposals. The earlier discussion 
containing more alternatives are found in 
https://mailarchive.ietf.org/arch/msg/slim/wR7iFD_gEINQh3RMGRFnj5kzGvA

The selected solutions for the functionality extensions can be included 
in the current draft or specified in a separate draft. If it is 
specified in a separate draft, the current draft needs to be checked and 
possibly adjusted so that it allows the selected syntax of the extensions.

*A. What we have specified in draft -08 is purely for lanuage  alternatives
*

The current specification is capable of negotiation of one language per 
media and direction. There is a way to express preference between 
languages within each media and direction, but no possibility to express 
preference between languages in the same direction in different media. 
There is freedom to use more than one media simultaneously if so decided 
but no indication if that is preferred.

*B. Indication of preference between media.*

There is a need to be able to indicate which of a set of language/media 
indications are more preferred alternatives than others.

Examples:

1. A user A want to get written English in text, A can as a less 
preferred alternative accept to get spoken English.  An answering party 
B who can use text will then respond with written text and get good 
satisfaction, while another answering user C without text capability 
will answer in spoken English and have a possibility for a reasonably 
successful call.
Without this indication, the first answering party B may have seen the 
spoken and written alternatives as true equal preference alternatives 
and answered with spoken English that will result in less satisfied users.

2. A user A prefer to receive spoken language, and can accept to receive 
text.   When answering party B can use spoken language, that will be 
satisfied, otherwise written language will be used.

3. A user A prefer to use spoken language in both directions, and can 
accept to use sign language in video in both directions. Answering party 
B has a clear indication of why both signed and written is indicated and 
can answer according to its capabilities trying to satisfy the 
preference for spoken language.

4. A user A prefer to use  sign language in both directions and can 
accept to use written language in both directions. Sign language users 
will use sign language, others will use text.

5. A user A prefer to send sign language and receive text (deaf-blind 
user) and can accept to send text.  In a call with a person with similar 
preferences, text will be used both ways, otherwise sign one way and 
text the other.

*Alternative coding proposals*

B.1 Based on draft -08, add the coding of an asterisk last in an 
attribute to mean lower preference for a lanugage/media combination than 
the one(s) without an asterisk.
example where audio and text are alternatives and text preferred
m=audio
a=hlang-recv:en*
m=text
a=hlang-recv:en

The asterisk is already specified to be used as an indication that the 
call should not be denied if language preferences cannot be met, but 
there is no rule for which attribute to put the asterisk for that 
purpose. This additional use of the asterisk brings a motivation to 
keeping the asterisk as a parameter on media level. There is slight, but 
manageable interaction between the two usages of the asterisk that needs 
to be expplained in the draft.

B.2. Change to the Accept-Language syntax and let the q-values have 
scope over the whole SDP.

The Issue tracker issues #34 and #39 propose to change to a more 
condensed syntax. Both should be satisfied by using a syntax similar to 
the Accept-Language. If that route is taken, it opens for a quite clean 
way to add indication of relative preference between languages in 
different media.

Example where sign language is higher preferred than text.

  m=video 51372 RTP/AVP 31 32
  a=hlang-recv:ase;q=0.9
  a=hlang-send:ase;q=0.9


  m=text 49250 RTP/AVP 98,99
  a=hlang-send:en;q=0.5,*;q=0.1
  a=hlang-recv:en;q=0.5

Note that the asterisk is used here only with its original meaning as indication that the call
should not be denied if languages can not be matched.

*C. **Indication of simultanous versus alternative languages.*

A way is required to indicate use of captioning and other situations 
where use of simultaneous languages in different modalities are preferred:

1. Preference for hearing spoken language and simultaneously read 
written language in text. ( captioning) .   This can be provided 
automatically in some settings, but also traditionally by a manned 
service. The written language may be the same as the spoken, or another 
language.

2. Preference for hearing spoken language and simultaneously seeing the 
speaker in video.   (lip-reading).  Easily and naturally provided once 
the need is known.

3. Preference for seeing sign language and simultaneously hear spoken 
language in audio.  ( for multiple users at the terminal, or for hearing 
persons with some limited knowledge in the specified sign language )    
One of the streams is provided by an interpreter.

4. Preference for hearing spoken language and simultaneously view 
written language in video. (captioning if we accept to specify text as 
overlay on video.)

Some of these can be acceptable also if just one of the language/media 
combinations can be provided, but is much more preferred if both can be 
provided together. In other cases it is essential to get both 
simultaneously. There is a need to be able to indicate this preference 
for getting the languages together.

*Alternative coding proposals:*

C.1  Use the -t- subtag for transformed content on a language indication 
defined in RFC 6497 as an indication that this language can be provided 
or is desired together with a language in another modality. Use this 
indication together with solution B.1

Example: Indicate that written English and spoken English are desired 
together and written English expected to be transformed.  but the call 
shall not be denied if that combination is not possible, and then 
written English is preferred.

m=text
a=hlang-recv:en-t-en
m=audio
a=hlang-recv:en*

The -t- indicated with the -recv direction shall not be understood that 
the indicated language needs to be transformed. It is just an 
expectation that enables it to express that the languages should be 
provided simultaneously.

C.2. Use the Accept-Language syntax for the hlang attributes and add the 
usage rules that q-values with less than .1 difference mean languages 
with a preference to be used together. Higher differences indicate that 
they are alternatives.  Thereby it is both possible to indicate 
simultaneity and preference if the simultaneity cannot be satisfied.

  m=audio 51372 RTP/AVP 0
  a=hlang-recv:ase;q=0.5
  a=hlang-send:ase;q=0.5


  m=text 49250 RTP/AVP 98,99
  a=hlang-send:en;q=0.51
  a=hlang-recv:en;q=0.51,*;q=0.1

The q-values differences are within 0.1 so it indicates a preference for getting both together,
but if that is not possible, text is preferred.


*Judgement of the alternatives:*
I have a preference for solutions B.2 and C.2 because they are logically 
most clean. They require that we accept the proposals in Issues #34 and 
#39 to move to the Accept-Language syntax.

B.1 and C.1 are easily added to the syntax of the current draft and have 
sufficient functionality for most cases. There will be some limitations. 
B.1 helps to motivate to keep the * parameter on media level. The use of 
the -t-  language subtag in B.2 may need discussion with language coding 
experts.

Summary:  I suggest to accept the proposal in #34, and use the coding 
B.2 and C.2 above for the functionality extensions. That would mean that 
the use of the asterisk is only for non-denial indication.


Gunnar

-- 
-----------------------------------------
Gunnar Hellström
Omnitor
[e-mail]
[phone]


Den 2017-04-25 kl. 20:25, skrev Bernard Aboba:
> Currently 10 Issues remain open from IETF Last Call:
> https://trac.ietf.org/trac/slim/report/1
>
> These include:
> Ticket 
> <https://trac.ietf.org/trac/slim/report/1?sort=ticket&asc=1&page=1> 
> Summary 
> <https://trac.ietf.org/trac/slim/report/1?sort=summary&asc=1&page=1> 
> Component 
> <https://trac.ietf.org/trac/slim/report/1?sort=component&asc=1&page=1> 
> 	Version 
> <https://trac.ietf.org/trac/slim/report/1?sort=version&asc=1&page=1> 
> Milestone 
> <https://trac.ietf.org/trac/slim/report/1?sort=milestone&asc=1&page=1> 
> 	Type 
> <https://trac.ietf.org/trac/slim/report/1?sort=type&asc=1&page=1> 
> Owner 
> <https://trac.ietf.org/trac/slim/report/1?sort=owner&asc=1&page=1> 
> Status 
> <https://trac.ietf.org/trac/slim/report/1?sort=status&asc=1&page=1> 
> Created 
> <https://trac.ietf.org/trac/slim/report/1?sort=created&asc=1&page=1>
> #27 <https://trac.ietf.org/trac/slim/ticket/27> 	The cases in the 
> "Silly states" section 5.4 are not all silly. 
> <https://trac.ietf.org/trac/slim/ticket/27> 
> negotiating-human-language 	2.0 	milestone1 
> <https://trac.ietf.org/trac/slim/milestone/milestone1> 	defect 
> [e-mail] <mailto:[e-mail]> 	new 
> Mar 22, 2017
> #19 <https://trac.ietf.org/trac/slim/ticket/19> 	Use Media Type 
> registration template <https://trac.ietf.org/trac/slim/ticket/19> 
> multilangcontent 	
> 	
> 	enhancement 	[e-mail] 
> <mailto:[e-mail]> 	assigned 	Aug 17, 2016
> #28 <https://trac.ietf.org/trac/slim/ticket/28> 	Examples section 5.5 
> requires expansion <https://trac.ietf.org/trac/slim/ticket/28> 
> negotiating-human-language 	2.0 	milestone1 
> <https://trac.ietf.org/trac/slim/milestone/milestone1> 	defect 
> [e-mail] <mailto:[e-mail]> 
> assigned 	Mar 22, 2017
> #32 <https://trac.ietf.org/trac/slim/ticket/32> 	Audio/Video 
> Coordination <https://trac.ietf.org/trac/slim/ticket/32> 
> negotiating-human-language 	2.0 	milestone1 
> <https://trac.ietf.org/trac/slim/milestone/milestone1> 	defect 
> [e-mail] <mailto:[e-mail]> 	new 
> Mar 22, 2017
> #34 <https://trac.ietf.org/trac/slim/ticket/34> 	Use the 
> Accept-Language syntax <https://trac.ietf.org/trac/slim/ticket/34> 
> negotiating-human-language 	2.0 	milestone1 
> <https://trac.ietf.org/trac/slim/milestone/milestone1> 	defect 
> [e-mail] <mailto:[e-mail]> 
> assigned 	Mar 22, 2017
> #35 <https://trac.ietf.org/trac/slim/ticket/35> 	Have an attribute to 
> abbreviate the bidirectionally-symmetric case 
> <https://trac.ietf.org/trac/slim/ticket/35> 
> negotiating-human-language 	2.0 	milestone1 
> <https://trac.ietf.org/trac/slim/milestone/milestone1> 	defect 
> [e-mail] <mailto:[e-mail]> 
> assigned 	Mar 22, 2017
> #38 <https://trac.ietf.org/trac/slim/ticket/38> 	Routing out of scope 
> <https://trac.ietf.org/trac/slim/ticket/38> 
> negotiating-human-language 	1.0 	milestone1 
> <https://trac.ietf.org/trac/slim/milestone/milestone1> 	defect 
> [e-mail] 
> <mailto:[e-mail]> 	new 	Apr 
> 25, 2017
> #39 <https://trac.ietf.org/trac/slim/ticket/39> 	Syntax Collapse 
> <https://trac.ietf.org/trac/slim/ticket/39> 
> negotiating-human-language 	1.0 	milestone1 
> <https://trac.ietf.org/trac/slim/milestone/milestone1> 	defect 
> [e-mail] 
> <mailto:[e-mail]> 	new 	Apr 
> 25, 2017
> #26 <https://trac.ietf.org/trac/slim/ticket/26> 	Make use of the 
> asterisk modifier on media level with session scope also for media 
> level purposes <https://trac.ietf.org/trac/slim/ticket/26> 
> negotiating-human-language 	2.0 	milestone1 
> <https://trac.ietf.org/trac/slim/milestone/milestone1> 	enhancement 
> [e-mail] <mailto:[e-mail]> 	new 
> Mar 22, 2017
> #29 <https://trac.ietf.org/trac/slim/ticket/29> 	Include more fields 
> for attribute registration from 4566bis 
> <https://trac.ietf.org/trac/slim/ticket/29>
>
>
>
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-- 
-----------------------------------------
Gunnar Hellström
Omnitor
[e-mail]
[phone]