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Re: [AVT] Q for 3984bis-06
Hi
I agree with Randell, in fact there are may cellphones today that can
both encode and decode at high levels, however the limited screensize
(or resolution) of a cell phone makes it useless to send full HD content
to a cell phone (unless it is connected to a TV or projector).
There are scenarios (not too far fetched IMHO) where a mobile user wish
to make a call to his/her friends or his famility who sit in comfortably
in front of a 50" TV. This means that we wish to send fullHD in one
direction while CIF is propably sufficient in the other direction. This
is a highly asymmetric scenario, the work on image attributes in MMUSIC
is partly done with this in mind.
I tried to address these asymmetric issues in a more generic way in
http://tools.ietf.org/id/draft-johansson-mmusic-asymmetric-media-00.txt,
it is however quite obvious that it is not too easy to do so, also the
interest is quite low.
With the above in mind I really believe it would be good if 3984bis
could make full asymmetry possible.
Regards
Ingemar
> ------------------------------
>
> Message: 2
> Date: Tue, 19 May 2009 12:24:09 -0400
> From: Randell Jesup <rjesup at wgate.com>
> Subject: Re: [AVT] Q for 3984bis-06
> To: stephen botzko <stephen.botzko at gmail.com>
> Cc: ron.even.tlv at gmail.com, Tom Taylor <tom.taylor at rogers.com>,
> avt at ietf.org
> Message-ID: <ybu63fxdpsm.fsf at jesup.eng.wgate.com>
> Content-Type: text/plain; charset=us-ascii
>
> stephen botzko <stephen.botzko at gmail.com> writes:
> >>>>
> >This is a real-world case; devices often have more encode horsepower
> >(and camera resolution) than they can actually display when
> receiving,
> >and they talk to other devices that *can* display that extra
> resolution..
> >>>>
> >
> >In our experience, the reverse situation is what actually
> happens - PCs
> >for instance frequently can decode and display HD images,
> but are often
> >limited to an SD webcam.
> >Can you name a couple of specific real devices that have these HD
> >cameras+encoders and the limited decoders?
>
> Mostly I'm not talking PC's (I agree with you there, though
> there are cases where it still may make sense, like when
> displaying video in a portion of the screen). I'm mostly
> talking mobile and dedicated devices with built-in LCDs; that
> would include Smartphones, dedicated videophones, "media"
> tablets, etc.
>
> For example, certain devices have been made with two
> different LCDs; one ~850x480, the other ~480x234, both with
> VGA-class cameras. Sending VGA content (or really anything
> beyond CIF) to the 480x234 display is just a waste of bits.
> If you wanted to and could negotiate it properly, though, you
> could send higher framerate CIF to that device, while it
> sends VGA at a lower framerate to a device that can show it.
>
>
> As for the comment about max-level=NN versus
> level-upgrade-allowed: I'd originally thought
> level-upgrade-allowed made the most sense, and in fact
> probably it does - let the answer respond with the highest
> level they can receive, and the offerer can send at whatever
> level they support.
>
> That's even easier to describe:
>
> level-upgrade-allowed=0 or 1:
> If the offer sets level-upgrade-allowed to 1, then
> an answer may
> include any level above the offered level in
> profile-level-id.
> The offerer may send at any level up to the level in
> the answer,
> and and answerer can send levels only up to the level in the
> offer. If this is not present or is set to 0, then
> the answer
> MUST NOT respond with a level greater than the level in
> profile-level-id.
>
> Note that this only allows the level to be increased in the
> answer; the profile and constraints are not allowed
> to change.
>
> --
> Randell Jesup, Worldgate (developers of the Ojo videophone),
> ex-Amiga OS team rjesup at wgate.com "The fetters imposed on
> liberty at home have ever been forged out of the weapons
> provided for defence against real, pretended, or imaginary
> dangers from abroad."
> - James Madison, 4th US president (1751-1836)
>
>
>