Re: [rtcweb] resolutions in draft-cbran-rtcweb-codec-01

[Ralph Giles <[e-mail]>]

On 17 November 2011 17:10, Aron Rosenberg <[e-mail]> wrote:

> I would suggest dropping 720x480 as it is neither 16:9 or 4:3 ratio, but a
> non-standard 3:2 ratio.

720x480 is a standard SD broadcast/DVD-Video resolution. With
non-square pixels and overscan, it can represent either 4:3 or 16:9.
Both proposed baseline codecs in this draft support non-square pixels,
since a lot of video is in this format.

I don't know how useful it is to have this as a SHOULD, but I would
ask why the corresponding PAL resolution (576 lines) isn't also
included if this one is considered useful.

> From a camera perspective 1024x768 and 800x60[0] are
> not well supported in video modes.

That's true, but these are common VGA screen resolutions. I think it's
useful to have them for presentations and screencasting. 1024x768 has
been a standard format for conference presentations for more than a
decade, and 800x600 is a useful fallback.

As to how this SHOULD should be read, I think the point here is that
while some devices have fixed formats due to hardware constraints,
others (like a desktop browser) are quite flexible, so it's helpful to
have a list of common resolutions implementers can choose to offer in
the absence of other constraints, and to test against.

 -r