Re: [Slim] Issue 43: How to know the modality of a language indication?

[Randall Gellens <[e-mail]>]

At 10:21 AM +0200 10/14/17, Gunnar Hellström wrote:

>  Den 2017-10-14 kl. 04:25, skrev Randall Gellens:
>>  At 1:46 PM -0700 10/13/17, Bernard Aboba wrote:
>>
>>>   Issue 43 ( 
>>> <https://trac.ietf.org/trac/slim/ticket/43>https://trac.ietf.org/trac/slim/ticket/43 
>>> ) results from a review comment that said 
>>> that a simple way is required to decide if a 
>>> language tag is a sign language or a written 
>>> or spoken language.
>>>
>>>   Some applications scan the IANA language 
>>> registry at startup for the word "Sign" in 
>>> the tag description:
>>>
>>> 
>>> <https://www.iana.org/assignments/language-subtag-registry/language-subtag-registry>https://www.iana.org/assignments/language-subtag-registry/language-subtag-registry
>>>
>>>
>>>   Currently, there are 319 language subtags 
>>> that include "Sign Language" in their 
>>> description.
>>>   Given the current layout of the language 
>>> subtag registry, it is not clear to me that 
>>> there is an easier way to determine which 
>>> tags represent sign languages.  Nor is it 
>>> within the SLIM WG charter to develop a 
>>> modification to the language subtag registry 
>>> to address this concern.
>>>   So I am wondering whether we might resolve 
>>> this with a Note outlining the problem but 
>>> not offering a solution.
>>
>>  I think the wording in -14 addresses the 
>> comment by accepting Dale's suggestion that, 
>> rather than know non-signed tags, it's the use 
>> of the exact same tag in both an audio and a 
>> video stream that is the indicator.  That both 
>> tightens up the technical issue and simplifies 
>> it greatly.
>>
>>  The only other instance where we might add such a note would be in 5.4:
>>
>>  5.4.  Undefined Combinations
>>
>>     With the exception of the case mentioned in Section 5.2 (an audio
>>     stream in parallel with a video stream with the exact same (spoken)
>>     language tag), the behavior when specifying a non-signed language tag
>>     for a video media stream, or a signed language tag for an audio or
>>     text media stream, is not defined.
>>
>>  We could add your suggested note to 5.4.
>>
>  <GH>We can replace 5.4 with a more explicit 
> section guiding applications to how to make the 
> deduction simple. So, instead of a note, I 
> suggest that we replace 5.4 with:
>
>  5.4 Relations between media and modality
>  There is no easy way to deduct the intended 
> modality from a language tag. Other 
> specifications may introduce specific notations 
> for modality used in a media or in relation to 
> a language tag. Applications not implementing 
> such specific notations may use the following 
> simple deductions.
>  - A language tag in audio media is supposed to indicate spoken modality.
>  - A language tag in text media is supposed to indicate  written modality.
>  - A language tag in video media is supposed to 
> indicate visual sign language modality except 
> for the case when it is supposed to indicate a 
> view of a speaking person mentioned in section 
> 5.2 characterized by the exact same language 
> tag also appearing in an audio media 
> specification.
>  - A language tag in media where the modality is 
> obvious or specified for the media subtype 
> definition is supposed to indicate that 
> modality.
>  - A language tag in other media descriptions 
> than above has undefined modality.
> 
> ---------------------------------------------------------------------------------------------------------------------

The suggested text makes a very different point than what's there now:

    the behavior when specifying a non-signed language tag
    for a video media stream, or a signed language tag for an audio or
    text media stream, is not defined in this document.

    The problem of knowing which language tags are signed and which are
    not is out of scope of this document.

An implementation could, for example, have a 
table (even a static table that's fixed) of 
language tags it knows to be for signed 
languages.  It could treat other tags as for 
non-signed languages.  This would be an imperfect 
approach (yielding incorrect results if a new 
signed language tag is introduced, e.g.), but 
might be good enough.


>  My note:  by this we currently consciously 
> exclude the following use and I am ok with that:
>  -text in mp4 video
>  -audio in mp4 video ( or is that only allowed in application/mp4 ??)
>  -any modality in message media
>  -most application media, however some may have 
> explicit descriptions in subtype specifications.
>
>  The exception with a view of a speaker stands 
> out as very odd now, requiring comparison of 
> language tags used in different media 
> descriptions, and requiring simultaneous use of 
> language in two different media that is 
> otherwise out of scope for this draft. It was 
> introduced while I still hoped that we could 
> introduce other dependencies between language 
> use in different media.  It is not the most 
> urgent media/language combination to specify. 
> It is also handled in 
> draft-hellstrom-slim-modality-grouping. So, 
> assuming that we can get progress on that 
> draft, we could clean up the current draft by 
> deleting the exception. I suggest that we 
> delete the exception.

I like the suggestion to delete the exception.

The exception is in 5.2:

    Note that while signed language tags are used with a video stream to
    indicate sign language, a video stream in parallel with an audio
    stream, both using the exact same (spoken) language tag, indicates a
    request for a supplemental video stream to see the speaker.

I agree that deleting this exception makes for a 
simpler and less complex draft.

-- 
Randall Gellens
Opinions are personal;    facts are suspect;    I speak for myself only
-------------- Randomly selected tag: ---------------
    The highlight of the annual Computer Bowl occurred when Bill Gates,
who was a judge, posed the following question to the contestants:
    "What contest, held via Usenet, is dedicated to examples of weird,
obscure, bizarre, and really bad programming?"
    After a moment of silence, Jean-Louis Gassee (ex-honcho at Apple)
hit his buzzer and answered "Windows."
                                          --Recounted by Adam C. Engst