Re: [avtext] Frame marking & VP9 SVC

Sergio Garcia Murillo <sergio.garcia.murillo@gmail.com> Tue, 28 March 2017 17:02 UTC

To: "Mo Zanaty (mzanaty)" <mzanaty@cisco.com>, "avtext@ietf.org" <avtext@ietf.org>
References: <ebdc7854-b390-d0e4-cfd1-d7df9c65aba4@gmail.com> <D4FFF329.6BA66%mzanaty@cisco.com>
From: Sergio Garcia Murillo <sergio.garcia.murillo@gmail.com>
Message-ID: <081e824d-f986-0818-267d-7cb13e836bb4@gmail.com>
Date: Tue, 28 Mar 2017 19:02:48 +0200
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Subject: Re: [avtext] Frame marking & VP9 SVC
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Hi Mo,

Thanks for checking it out.

Just one comment, please take into account that in PERC context the 
payload is encrypted, so the SFU will not have access to the media 
payload and will only be able to rely on the frame marking extensions to 
perform the selective forwarding.

Best regards
Sergio

On 28/03/2017 18:53, Mo Zanaty (mzanaty) wrote:
> Hi Sergio,
>
> Good catch. The VP9 payload format has changed since the Frame Marking 
> LID extensions were defined. The VP9 authors expect it may change 
> further. Based on discussion during today's AVT session, we will 
> remove VP9 from the Frame Marking draft (which will help avoid MIS-REF 
> later), and move that information to the VP9 payload format so it can 
> evolve without diverging.
>
> The discussion on U and P bits was more nuanced. The main point is 
> Frame Marking should help identify when layer refresh has occurred and 
> when layer up switching is possible. We will add some text on this for 
> simple, fixed scalability structures, and note that complex, non-fixed 
> structures require payload-specific inspection and logic that no extra 
> bits will completely eliminate.
>
> Cheers,
> Mo
>
> From: avtext <avtext-bounces@ietf.org 
> <mailto:avtext-bounces@ietf.org>> on behalf of Sergio Murillo 
> <sergio.garcia.murillo@gmail.com <mailto:sergio.garcia.murillo@gmail.com>>
> Date: Tuesday, March 28, 2017 at 9:54 AM
> To: "avtext@ietf.org <mailto:avtext@ietf.org>" <avtext@ietf.org 
> <mailto:avtext@ietf.org>>
> Subject: [avtext] Frame marking & VP9 SVC
>
> Hi,
>
> I have been implementing the framemarking for PERC and I have some 
> doubts regarding the VP9 LID mapping.
>
> First, is that according to 
> https://tools.ietf.org/html/draft-ietf-payload-vp9-03 there are no 
> quality layers on VP9 SVC they are considered as case of spatial layers:
>
>     VP9 supports quality layers as spatial layers without any resolution
>     changes; hereinafter, the term "spatial layer" is used to represent
>     both spatial and quality layers.
>
> So, shouldn't the LID reference to the spatial layer ID only  and omit 
> the quality layer id completely? Also, the spatial layer id is 3 bits 
> on that draft.
>
> Also, in order to be able to implement VP9 SVC layer selection, the 
> SFU needs the information of the P and U bits of the VP9 header 
> description:
>
>     P: Inter-picture predicted layer frame.  When set to zero, the layer
>        frame does not utilize inter-picture prediction.  In this case,
>        up-switching to current spatial layer's frame is possible from
>        directly lower spatial layer frame.  P SHOULD also be set to zero
>        when encoding a layer synchronization frame in response to an LRR
>        [I-D.ietf-avtext-lrr 
> <https://tools.ietf.org/html/draft-ietf-payload-vp9-03#ref-I-D.ietf-avtext-lrr>] message (seeSection 5.4 
> <https://tools.ietf.org/html/draft-ietf-payload-vp9-03#section-5.4>).  When P is set to
>        zero, the T bit (described below) MUST also be set to 0 (if
>        present).
>
>     U: Switching up point.  If this bit is set to 1 for the current
>        frame with temporal layer ID equal to T, then "switch up" to a
>        higher frame rate is possible as subsequent higher temporal
>        layer frames will not depend on any frame before the current
>        frame (in coding time) with temporal layer ID greater than T.
>
> Without that info, the SFU won't be able to upscale, so it would be 
> required to add that information on the VP9 LID.
> Including that changes, it would be something like this:
>
>      0                   1                   2                   3
>      0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
>     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
>     |  ID=2 |  L=2  |S|E|I|D|B| TID |0|0|0|P|U|SID  |    TL0PICIDX  |
>     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
>
> Best regards
> Sergio

[avtext] Frame marking & VP9 SVC Sergio Garcia Murillo
Re: [avtext] Frame marking & VP9 SVC Mo Zanaty (mzanaty)
Re: [avtext] Frame marking & VP9 SVC Sergio Garcia Murillo
Re: [avtext] Frame marking & VP9 SVC Jonathan Lennox
Re: [avtext] Frame marking & VP9 SVC Bernard Aboba
Re: [avtext] Frame marking & VP9 SVC Sergio Garcia Murillo
Re: [avtext] Frame marking & VP9 SVC Bernard Aboba
Re: [avtext] Frame marking & VP9 SVC Sergio Garcia Murillo
[avtext] VP9 P bit (was Re: Frame marking & VP9 S… Jonathan Lennox