[MMUSIC] Re: Turntaking indication on the session level

[Paul Kyzivat <[e-mail]>]

Gunnar,

I'm not an expert in either the PTT stuff or your text mode stuff, so I 
might not have a lot to offer here.

Once upon a time, years ago now, there was some discussion of using half 
duplex in presence to denote PTT. But the PTT people never bought it.

As best I understand the PTT stuff in IMS (POC), it is handled via a 
special set of floor control conventions conveyed in RTP. (Someone will 
correct me if I am wrong.) Meanwhile, the media stream itself has no 
indication in SDP that it is half duplex.

So I wonder if this is so different from your usage. I think what might 
be appropriate is some way of conveying what floor control convention is 
to be followed for this stream. There could be one value that denotes 
the convention you want to use for text, and another that denotes the 
convention used for POC. (Different kinds of PTT may use different ones.)

AFAIK there is currently no attribute that does this. So maybe something 
like:

    a=floor-control-type: token

	Paul

Gunnar Hellström wrote:
> Paul,
> I changed the Subject line since we need to find another home for the
> turn-taking indication than the media-content attributes.
> 
> What I would like to find or define is a parameter on the session level that
> is just an indication about the type of limitations in communication that
> may occur on the user interface side of a SIP device.
> 
> It should not influence control of media between SIP devices, but rather be
> used to adapt the user interface of the terminal receiving this indication
> to the communication habits.
> 
> For voice, it is not really half duplex like Push To Talk, because during
> periods of voice it is possible to talk in both directions, it is only usage
> patterns that usually limit voice usage to one direction.
> 
> During text transmission. Text may be handled in a half-duplex fashion, like
> "push to text". But there are situations where more or less full duplex is
> possible.
> 
> Would you recommend to signal this kind of media restrictions in the user
> interface during a session by using the duplex="half" indication in the
> contact field?
> Note that the restrictions shall not apply to the media transport in the SIP
> call.
> 
> Gunnar
> 
> 
> ----------------------------------------------------------------------------
> -
> Gunnar Hellström, Omnitor
> [e-mail]
> 
> 
> -----Original Message-----
> From: Paul Kyzivat [mailto:[e-mail]]
> Sent: Monday, August 28, 2006 6:28 PM
> To: Gunnar Hellström
> Cc: Cullen Jennings; Arnoud van Wijk; 'Colin Perkins'; 'MMusic';
> 'Gonzalo Camarillo'
> Subject: Re: [MMUSIC] I-D
> ACTION:draft-ietf-mmusic-sdp-media-content-04.txt
> 
> 
> Gunnar,
> 
> What you are now describing is beginning to sound like the PTT (Push To
> Talk) half duplex audio.
> 
> 	Paul
> 
> Gunnar Hellström wrote:
>> Cullen,
>> Thanks for giving the media-content the required decision to move on.
>>
>> This gives us a reason to review the requirements behind the proposed
> "txp"
>> parameter for text turntaking.
>> It can in fact be a combined audio/text turn-taking procedure. Real-time
>> text and voice takes turns during a call in many cases on the PSTN side.
> And
>> then, during text periods, turn-taking is often used for text in the two
>> directions.
>>
>> That leads me to think that we should look at session level attributes.
>> Such as
>> Contact: duplex="half" or a suitable more precise indication in SIP.
>>
>> It should be remembered that the media flow itself should be left to be
> full
>> duplex on the IP side.
>>
>> More on this soon under another subject line.
>>
>> Gunnar
>>
>> --------------------------------------------------------------------------
> --
>> -
>> Gunnar Hellström, Omnitor
>> [e-mail]
>> Mob: [phone]
>> Phone: [phone]
>> www.omnitor.se
>>
>>
>> -----Original Message-----
>> From: Cullen Jennings [mailto:[e-mail]]
>> Sent: Friday, August 25, 2006 6:00 PM
>> To: Arnoud van Wijk
>> Cc: 'MMusic'; 'Gunnar Hellström' ; 'Gonzalo Camarillo'; 'Colin Perkins'
>> Subject: Re: [MMUSIC] I-D
>> ACTION:draft-ietf-mmusic-sdp-media-content-04.txt
>>
>>
>>
>> Ok, folks, with my AD hat on here, here is what I would appreciate it
>> if you would do:
>>
>> Remove these two attributes from this draft - either we have come to
>> consensus they should not be here or we have at least agreed that we
>> don't have consensus on it.
>>
>> Update the description of what are appropriate future extensions of
>> this to include text along the lines of Gonzalo's
>>
>>   "Content tokens should consist of a meta description of the
>> contents of a media stream. That is, whether the stream contains
>> slides, or is the main stream, etc. Content tokens should not
>> describe things like what to do in order to handle a stream (e.g.,
>> use user-level floor control)."
>>
>> Resubmit this draft soon and I will start IETF LC on it. The WG can
>> provide any comments that might typically be WGLC comments in IETF LC.
>>
>> Go to work on another draft that solves the txp, user-floor problem -
>> I will do what I can to help expedite that draft. One thing  that I
>> think will help is if the draft is clear about what happens  when a
>> device that receives this signally and how that changes the receiving
>> devices behavior.
>>
>> Thanks, Cullen
>>
>>
>> On Aug 25, 2006, at 1:43 AM, Arnoud van Wijk wrote:
>>
>>> Very well.
>>> That is clear then.
>>> We shall focus on the separate SDP attribute.
>>>
>>> Arnoud
>>>
>>> Arnoud A. T. van Wijk
>>> AnnieS New Technology
>>> www.AnnieS.nl
>>> Mobile textphone (SIP): [e-mail]
>>>
>>>> -----Original Message-----
>>>> From: Gonzalo Camarillo [mailto:[e-mail]]
>>>> Sent: vrijdag 25 augustus 2006 10:02
>>>> To: Arnoud van Wijk
>>>> Cc: 'Colin Perkins'; 'Gunnar Hellström'; 'Cullen Jennings'; 'MMusic'
>>>> Subject: Re: [MMUSIC] I-D ACTION:draft-ietf-mmusic-sdp-media-content-
>>>> 04.txt
>>>>
>>>> Hi,
>>>>
>>>> my take on this would be to remove the 'user-floor' and the 'txt'
>>>> tokens
>>>> from this draft and add a clearer explanation of what the content
>>>> tokens
>>>> (current and future) should describe.
>>>>
>>>> Content tokens should consist of a meta description of the
>>>> contents of a
>>>> media stream. That is, whether the stream contains slides, or is the
>>>> main stream, etc. Content tokens should not describe things like
>>>> what to
>>>> do in order to handle a stream (e.g., use user-level floor control).
>>>> That type of stuff would be better described in a separate SDP
>>>> attribute, as suggested by Colin at some point.
>>>>
>>>> That separate SDP attribute would resolve the use cases Arnoud and
>>>> Gunnar have in mind, which are very interesting as well.
>>>>
>>>> Thanks,
>>>>
>>>> Gonzalo
>>>>
>>>>
>>>> Arnoud van Wijk wrote:
>>>>> Hi Colin,
>>>>> I agree with Gunnar and disagree with you.
>>>>> The txp content label is no different the the other content
>>>>> labels IMHO.
>>>>> And again, it is NOT about a PSTN textphone, but about turntaking be
>>>> used in
>>>>> the call since it media stream contains real-time text to be used in
>>>> turn
>>>>> taking method.
>>>>> It is not about a special phone, or limited device that is elsewise
>>>> unable
>>>>> to be connected.
>>>>> But I am still waiting on Gonzalo's view on this.
>>>>>
>>>>> Greetz
>>>>>
>>>>> Arnoud
>>>>>
>>>>> Arnoud A. T. van Wijk
>>>>> AnnieS New Technology
>>>>> www.AnnieS.nl
>>>>> Mobile textphone (SIP): [e-mail]
>>>>>
>>>>>> -----Original Message-----
>>>>>> From: Colin Perkins [mailto:[e-mail]]
>>>>>> Sent: woensdag 23 augustus 2006 10:15
>>>>>> To: Gunnar Hellström
>>>>>> Cc: Cullen Jennings; MMusic; Gonzalo. Camarillo@ericsson. com
>>>>>> Subject: Re: [MMUSIC] I-D ACTION:draft-ietf-mmusic-sdp-media-
>>>>>> content-
>>>>>> 04.txt
>>>>>>
>>>>>> Gunnar,
>>>>>>
>>>>>> On 23 Aug 2006, at 08:28, Gunnar Hellström wrote:
>>>>>>> It is allowed to have more than one content attribute.
>>>>>> True, but irrelevant.
>>>>>>
>>>>>>> There is no difference in characteristics of the txp attribute
>>>>>>> compared to the other accepted attributes.
>>>>>>> slides come from a slide showing application that has a specific
>>>>>>> expected behaviour of showing one slide at a time.
>>>>>>> Speaker has its source in a camera, a keyboard and a microphone
>>>>>>> that likely requires some polite method to be allowed to control.
>>>>>>> All have sources in devices and have a mixed meaning of device
>>>>>>> indications and preparation for human behaviour when using the
>>>>>>> contents.
>>>>>>> There is no reason to separate out txp in this collection of
>>>>>>> attributes.
>>>>>> I disagree, for the reasons I have previously explained.
>>>>>>
>>>>>>> With the new slimmed description it is of the same size and level
>>>>>>> as the others.
>>>>>> The "size and level" of the description was never the problem.
>>>>>> Instead, there is concern that its semantics don't fit with the
>>>>>> content label.
>>>>>>
>>>>>>> As I remember it, the last call just asked for an improved
>>>>>>> description, not questioning the idea to include the attribute.
>>>>>> I am explicitly questioning the inclusion of the txp label in the
>>>>>> media content draft. I believe it should be removed to a separate
>>>>>> draft, defining a new SDP attribute. We should also consider if the
>>>>>> user-floor label should be removed too.
>>>>>>
>>>>>> A simple rewording of the description of the txp label, of the type
>>>>>> you are proposing, without considering the semantics, will not
>>>>>> resolve this issue.
>>>>>>
>>>>>> Colin
>>>>>> _______________________________________________
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> 

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