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

From: Ralph Giles <[email-masked]>
Date: Fri, 2 Dec 2011 15:18:16 -0800

On 29 November 2011 21:18, James M. Polk <[email-masked]> wrote:

> not meaning to open a can of worms, but what still requires interlaced
> video? Most new things convert I to P, but less of these convert P to I.

I guess I didn't respond to this, but what Harald said is a good
summary. There are certainly still interlaced display devices in
active use. For example, the screen in our video conferencing room
only does 1080i, not 1080p, but the issue is more going the other
direction.

There are reasons to produce interlaced content still; for high-motion
sources (like sport) the additional temporal resolution can give a
better experience without the (mostly unsupported) overhead of 60p.
That said, interlaced media support shouldn't be a requirement for
this draft.

 -r

---

From: Stephen Botzko <[email-masked]>
Date: Mon, 5 Dec 2011 16:38:50 -0500

> That said, interlaced media support shouldn't be a requirement for

I believe there is a lot of IPR on interlaced coding, which should also be
taken into account.

It is quite easy to convert 30p to 60i for display.

On the other hand, turning 60i to 30p for progressive PC displays is
certainly possible, but most software PC players do a very poor job of it.
Interlaced coding and deinterlacing both carry a delay penalty.

So I think interlaced media should be a non-requirement for RTCWEB.

BTW, ESPN uses 720p60 instead of 1080i60 in order to get better motion
handling, so I am puzzled by the (mostly unsupported) comment.

- sb

>  -r
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