Re: [MMUSIC] New Version Notification for draft-abhishek-mmusic-superimposition-grouping-00.txt

[Paul Kyzivat <[e-mail]>]

On 12/12/20 2:06 PM, Christer Holmberg wrote:
> Hi,
> 
> A few comments (some of which I gave already previously):

Christer covered most of what I wanted to say. I'll just add a few 
tweaks below.

> Q1:
> 
> In Section 1, where you talk about the limitations of the mechanism, you should mention that CLUE must be used something more "fancy" is needed.
> 
> ---
> 
> Q2:
> 
> In Section 3, you require a specific order of the m- lines in the SDP. I think SDP explicitly says that the order of m- lines is not relevant. Also, I know that parsers may change the orders of the m- lines.
> 
> (I also think that any counting should start from 1, not 0)
> 
> My suggestion would be to have an explicit "order" attribute instead.

I think it would be acceptable to use the order of the tokens in the 
a:group line to define the ordering of the "layers". The "lowest" layer 
would then be the background on which the others are overlain. (Whether 
the lowest layer is the first or last in the list is TBD.)

> ---
> 
> Q3:
> 
> The example in Section 6 talks about "a background video". But, this background video is not described in the SDP.
> 
> Related to that, if the SDP describes multiple "background videos", you need to describe how you map superimposed videos to a specific background video.
> 
> Based on the text in Section 3 (see Q2), I am not sure whether the 0th m- line is supposed to be the background video, but the text in Section 6 says that both m- lines are for superimposed video streams.

See my comment above.

The background layer would presumably have a transparency of zero.

(It would also be good to specify that if the transparency attribute is 
omitted it defaults to zero.)

> ---
> 
> Q4:
> 
> What happens to the superimposed videos if I disable/remove/mute the background video?
> 
> ---
> 
> Q5:
> 
> This is editorial, but please call the group attribute something else than just "S". "supim", "spim" or something :)

Yes please. "S" is way to cryptic.

	Thanks,
	Paul

> Regards,
> 
> Christer
> 
> 
> 
> -----Original Message-----
> From: mmusic <[e-mail]> On Behalf Of Rohit Abhishek
> Sent: lauantai 12. joulukuuta 2020 0.28
> To: [e-mail]
> Subject: [MMUSIC] FW: New Version Notification for draft-abhishek-mmusic-superimposition-grouping-00.txt
> 
> Dear All,
> 
> A new version of the draft “SDP Superimposition Grouping framework” has been uploaded.
> We have changed the name from  “SDP Overlay Grouping framework for immersive telepresence media streams” to  “SDP Superimposition Grouping framework” as the previous name wasn’t an accurate description of the content. Therefore, we had to start from version 00.
> 
> Thank you all for the comments/suggestions on the previous draft.
> We have tried to address them in this version. Specifically, a transparency attribute and an informative Section on relationship with CLUE has been added.
> 
> Comments/Questions/Feedbacks are welcome.
> 
> Best Regards,
> Rohit
> 
> On 12/11/20, 12:41 PM, "[e-mail]" <[e-mail]> wrote:
> 
> 
>      A new version of I-D, draft-abhishek-mmusic-superimposition-grouping-00.txt
>      has been successfully submitted by Rohit Abhishek and posted to the
>      IETF repository.
> 
>      Name:		draft-abhishek-mmusic-superimposition-grouping
>      Revision:	00
>      Title:		SDP Superimposition Grouping framework
>      Document date:	2020-12-11
>      Group:		Individual Submission
>      Pages:		8
>      URL:            https://www.ietf.org/archive/id/draft-abhishek-mmusic-superimposition-grouping-00.txt
>      Status:         https://datatracker.ietf.org/doc/draft-abhishek-mmusic-superimposition-grouping/
>      Htmlized:       https://datatracker.ietf.org/doc/html/draft-abhishek-mmusic-superimposition-grouping
>      Htmlized:       https://tools.ietf.org/html/draft-abhishek-mmusic-superimposition-grouping-00
> 
> 
>      Abstract:
>         This document defines semantics that allow for signaling a new SDP
>         group "S" for superimposed media in an SDP session.  The "S"
>         attribute can be used by the application to relate all the
>         superimposed media streams enabling them to be added as an overlay on
>         top of any media stream.  The superimposition grouping semantics is
>         required, if the media data is separate and transported via different
>         sessions.
> 
> 
> 
> 
>      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.
> 
>      The IETF Secretariat
> 
> 
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