[rtcweb] Video resolution SHOULDs (Re: resolutions in draft-cbran-rtcweb-codec-01)

On 11/17/2011 11:19 AM, Roni Even wrote:
>
> Hi,
>
> The text in the draft on video codec is
>
> o MUST support a minimum resolution of 320X240
>
> o SHOULD support resolutions of 1280x720, 720x480, 1024x768,
>
> 800x600, 640x480, 640 x 360 , 320x240
>
> I propose adding 1920 x 1080 to the SHOULD. This resolution are used
> by video conferencing systems
>

I think I want to object to making this a SHOULD, but it's possible we
just don't understand the requirement the same way....

The RFC 2119 SHOULD definition says:

3. SHOULD This word, or the adjective "RECOMMENDED", mean that there
may exist valid reasons in particular circumstances to ignore a
particular item, but the full implications must be understood and
carefully weighed before choosing a different course.

When designing an RTCWEB implementation for my mobile phone, with its
(comparatively) microscopic screen and anemic processor and battery, it
takes approximately zero seconds to decide that I won't waste energy
(literally) on decoding HD; I'll make sure I negotiate down to something
more sane for me if someone's unkind enough to suggest it to me.

I would be happy to write the requirement as

SHOULD support resolutions of 1920x1080, 1280x720, 720x480, 1024x768,

800x600, 640x480, 640 x 360 , 320x240 if these resolutions can be
displayed on the target device

but I would not be happy to just extend the requirement as it is
proposed today.

(Yes, I know, this means that I've turned down-negotiation of video
resolution into a MUST. I think it already is, but I think we haven't
talked explicitly about it.)

> I also assume that there will be a way to negotiate the video
> parameters (no issue if we use offer/ answer RFC 3264)
>
> Roni Even
>
>
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