Subject: [clue] Comments on draft-ietf-clue-telepresence-use-cases-01

From: Christian Groves <[email-masked]>
Date: Wed, 31 Aug 2011 11:03:08 +1000

Hello all,

As Roni mentioned I provided some comments to the authors of 
draft-ietf-clue-telepresence-use-cases-01.

Here they are:

Comments:
---------
1) Section 1 2nd paragraph: [CNG] Having participated in the work I know 
what is meant here, but if someone new reads this draft there doesn’t 
seem to be any linking text between the fact that there are multiple 
standards in use and that by describing multiple streams, 
interoperability is somehow now guaranteed? I assume it the fact that by 
allowing a common way to describe streams that systems that have 
different capabilities are able to negotiate a common set of capabilities???

2) Section 1 4th paragraph: [CNG] Will this be reworded when the 
document goes for WGLC? I take additional scenarios won’t be added after 
that time.

3) Section 2: [CNG] This section seems to convey a “mixed” message. The 
initial sentence says “ This section describes the general 
characteristics of the use cases and what the scenarios are intended to 
show. “ However a good part of the section (bullet list down) doesn’t 
talk about the use cases it’s a problem statement. Perhaps it should go 
into the introduction or be a section titled “problem statement” or similar?

4) Section 2 List item 4: "The number of audio channels"
[CNG] Should this be number and type of microphones? Or is there some 
significance of the "channel" usage?

5) Section 3: [CNG] Will there be any attempt to link the requirements 
to certain uses cases?? For example: The RTCWEB requirements document 
indicates which requirements are derived from which use cases.

6) Section 3.x: [CNG] The framework draft sect 6.1 indicates that media 
descriptions are dynamic. I.e. capabilities may change. There’s nothing 
explicit in the requirements to support this. Likewise there doesn’t 
appear to be a use case to support that. Do we need to add one for that?

7) Section 3.2 Para 2: "...and 1 screen and 1 camera at the other site, 
connected by a point to
point call."
[CNG] What’s the relevance of this text? It’s not included in the 
symmetric case? And this aspect doesn’t seem to be further discussed in 
the use case.

8) Section 3.4 Para 4: "..In a multipoint meeting, the presentation 
streams for the currently active presentation are always distributed to 
all sites in the meeting, so that the presentations are viewed by all."
[CNG] How does this relate to the framework? i.e. even though currently 
presentations are distributed to all participants the framework allows 
different video captures to be sent to different remote systems.

9) Section 3.5 Para 3: "In most cases a transcoding intermediate device 
will be relied upon to produce a single stream, perhaps with some kind 
of continuous presence."
[CNG] I’m not sure what “continuous presence” has to do with a 
transcoding device??? Maybe some clarifying text could be added?

10) Section 3.5 Para 6: "For the software conferencing participant,..."
[CNG] PC-based? Software conferencing participant isn’t in the 
introduction paragraph in sect. 3.5.

11) Section 3.6 Para 1: "The importance of this example is that the 
multiple video streams are
not used to create an immersive conferencing experience with panoramic 
views at all the site."
[CNG] I’m not getting the meaning here. Is there a word missing? i.e. 
“panoramic views at all the sites”, “panoramic view of the sites” etc?

Editorial
---------
1) List of authors mentions T.Eubanks
[CNG] should it be M.Eubanks?

2) Abstract: Telepresence conferencing systems seek to create the sense 
of <<participants>> really being present.
[CNG]I guess it’s the participants really being present rather than the 
telepresence system.

3) General: Various terms are used to indicate the apparent size of 
participants: full-size, actual-sized etc. I think we should 
consistently the same term (I think "actual sized" is being favoured). 
Otherwise we should documents the difference between these terms if some 
different is meant.

4) Sect.1 Introduction, Para 2. Addition: ...assistance and expensive 
additional equipment which translates from one vendor<<’s protocols>> to 
another...

5) Sect.1 Para 5 suggested rewording: "Point-to-point and Multipoint 
telepresence conferences are considered. In some use cases, the number 
of displays the same at all sites, in others, the number of displays 
differs at different sites. Both use cases are considered. Also included 
is a use case describing display of presentation material or content."
[CNG] The term "use case" should be used consistently i.e. instead of 
"case" or "scenario"
[CNG] “similar” means not necessary identical to i.e. different. So 
"same" should be used.

6) Sect.1 Para 6: "section" in lower case.

7) Sect.2 Para 2: (around 60") [CNG] What does it relate to, width, 
diagonal, what aspect ratio? We should probably be more specific.

8) Sect.2 Para 2 change: "The cameras used to present.." to "The cameras 
used to capture..." AND "There may also be other cameras, such as for 
document display." to ""There may also be other cameras, such as for 
document capture."

9) Sect.2 Para 2 AND General: [CNG] The terms "screen", "monitor" and 
"display" are all used interchangeably in the draft. It would be good to 
use a single term.

10) Section 2 List item 8: "Similar or dissimilar number of primary 
screens at all sites"
[CNG] As per above is this really “the same or a different” number of? 
Or is there a reason that there is some ambiguity in this definition?
Also “Type” is described against “presentation displays” is there a 
reason that the primary screens may be a different type?

11) Section 2 1st para under list [delete]: "This state of affairs is 
not acceptable for the continued growth of telepresence >>>- we 
believe<<< telepresence systems should have the same ease of 
interoperability as do telephones."

12) Section 2 2nd last paragraph [delete]: "...and simultaneously 
providing a spatial audio sound stage that is consistent with the video 
 >>>presentation<<<.
[CNG] Not to confuse a presentation video stream as opposed to a 
participant video stream.

13) Section 3.2 para 3: "maneuvers" to "manoeuvres"

14) Section 3.4 bullet list, split point 2 to create point 3:
3. An educator who is presenting a multi-screen slide show. This show 
requires that the placement of the images on the multiple displays at 
each site be consistent.

15) Section 3.5 para 3 [change]: "In most cases a transcoding 
intermediate device will..." to " In most cases an intermediate 
transcoding device will..."

16) Section 3.5 para 6 [add]: "Or, it could be multiple streams, similar 
to an immersive <<telepresence system>> but with a smaller screen.

17) Section 3.5 last para [add]: "...the same way that immersive system 
signals actions."

18) Section 3.7 para 1: [CNG] The reference to Allardyce and Randal 
doesn't match the reference section "Allardyre" and "Randall"???

19) Section 7. [CNG] ITU docs are not referenced? E.g. H.239, H.264, H.323,

20) Author's addresses: Is Marshall address correct? I get a bounce when 
sending to him.

+ Other small nits, spaces missing etc. Communicated to the editor.

Regards, Christian

---

From: Roni Even <[email-masked]>
Date: Wed, 31 Aug 2011 10:24:47 +0300

Hi Christian,
Thanks for the review see inline
Roni

> -----Original Message-----
> From: [email-masked] [mailto:[email-masked]] On Behalf Of
> Christian Groves
> Sent: Wednesday, August 31, 2011 4:03 AM
> To: [email-masked]
> Subject: [clue] Comments on draft-ietf-clue-telepresence-use-cases-01
> 
> Hello all,
> 
> what is meant here, but if someone new reads this draft there doesn't

My understanding is that even though there are some standards in place there
is no standard way to describe the streams behavior or semantics preventing
interoperability even between systems with same capabilities from different
manufacturers.

> document goes for WGLC? I take additional scenarios won't be added
> after
> that time.

Propose to delete this paragraph.

> 
> 3) Section 2: [CNG] This section seems to convey a "mixed" message. The
> initial sentence says " This section describes the general
> show. " However a good part of the section (bullet list down) doesn't
> talk about the use cases it's a problem statement. Perhaps it should go
> into the introduction or be a section titled "problem statement" or
> similar?

The bullets in the section talk more about the characteristics of a general
TP systems.  I do not think it is a problem statement so maybe we should
revised the first paragraph to talk about TP system characteristics.

> descriptions are dynamic. I.e. capabilities may change. There's nothing
> explicit in the requirements to support this. Likewise there doesn't
> [CNG] What's the relevance of this text? It's not included in the
> symmetric case? And this aspect doesn't seem to be further discussed in
> the use case.

I suggest to remove the sentence on point to point call.

> different video captures to be sent to different remote systems.

This draft is about use cases. It describes how systems from different
manufacturers work so it is good to describe the presentation streams usage.

> [CNG] I'm not sure what "continuous presence" has to do with a

The transcoding device may have the capability to also create a composed
image (continuous presence)

> [CNG] PC-based? Software conferencing participant isn't in the

For consistency should be PC based in section 3.5.

> [CNG] I'm not getting the meaning here. Is there a word missing? i.e.
> "panoramic views at all the sites", "panoramic view of the sites" etc?
> 
> 
> Editorial
> ---------
> [CNG]I guess it's the participants really being present rather than the
> telepresence system.
> 
> additional equipment which translates from one vendor<<'s protocols>>
> to
> another...
> 
> [CNG] "similar" means not necessary identical to i.e. different. So
> "same" should be used.
> 
> [CNG] As per above is this really "the same or a different" number of?
> Also "Type" is described against "presentation displays" is there a

Allardyce and Randall http://adsabs.harvard.edu/abs/1983ddi..rept.....A 

> _______________________________________________
> clue mailing list
> [email-masked]
> https://www.ietf.org/mailman/listinfo/clue

---

From: Christian Groves <[email-masked]>
Date: Wed, 31 Aug 2011 20:05:08 +1000

Hello Roni,

Thanks for the responses. Please see my replies below.

Regards, Christian

> interoperability even between systems with same capabilities from different
[CNG] I agree. My point was that the current text in the use case 
document I think is overly simplistic. Being able to describe something 
suddenly doesn't solve interoperability. e.g. I can use SDP to describe 
plenty of things it doesn't mean that it will make it interoperable with 
another party. There's more built around it i.e. offer / answer to be 
able to negotiate a common set. Its the text that describes the protocol 
aspects of CLUE such as the hint->, <-capabilities, ->configure.

> Propose to delete this paragraph.
[CNG] OK
> revised the first paragraph to talk about TP system characteristics.
[CNG] I don't think all of the text is a problem statement just certain 
aspects of section 3. I think the section is a bit of mixed bag in what 
it is trying to achieve. The heading says "Telepresence Scenarios 
Overview" - there's elements of this e.g. saying what in and out of 
scope. The first sentence talks about "Characteristics" - there's 
element of this also in the paragraphs and list. Then there's text like 
the 3rd paragraph which to me reads like a problem statement.
> I suggest to remove the sentence on point to point call.
[CNG] OK
> manufacturers work so it is good to describe the presentation streams usage.
[CNG] I'm not disagreeing with leaving it in. It should be mentioned. I 
was just thinking ahead to see what requirement was derived from this 
statement. One could derive the requirement "A presentation capture 
SHALL be distributed to all participants" or "A presentation capture MAY 
be distributed to all participants or a subset". This requirement would 
then need to be supported in the CLUE framework. So I was really 
questioning what the intention was for this text?

> image (continuous presence)
[CNG] OK, I understand the intention. Could you include some clarifying 
text in an updated draft?
>> of<<participants>>  really being present.
>> not acceptable for the continued growth of telepresence>>>- we
>> to an immersive<<telepresence system>>  but with a smaller screen.
>>
[CNG] OK