[opendtv] Re: MPs back Ofcom stance on spectrum sale
- From: Craig Birkmaier <craig@xxxxxxxxx>
- To: opendtv@xxxxxxxxxxxxx
- Date: Mon, 21 May 2007 11:19:59 -0400
At 7:28 AM -0400 5/21/07, Tom Barry wrote:
One could image the next rational step up in frame rate to be 48,
50, 60, or 72 Hz. Anybody guess if 60 Hz will be the likely target?
The rational thing to do would be to move to 24/36/72 Hz.
36 is more than adequate for most low motion applications like
talking head shows, and is enough of an improvement over 24P to be
useful, whereas 30P is not being used because it is too close to 24P.
48P is also interesting.
As for 60P, I am beginning to wonder if we will ever be rid of 59.94.
Also, anybody ever seen what it looks like to display 72Hz on a 60
Hz fixed frequency display? Is the judder noticeable or is already
fast enough to hide it?
I have seen tests of 72P on 60P. This is typically done by dropping
every sixth frame. It looks OK, but any form of pull-down/pull-up is
a kludge.
The real question is why would anyone build a fixed frequency display today?
The major advantage of emerging display technologies is that they are
frame rate flexible for updates that are at a lower rate than the
maximum refresh.
One could also imagine the next rational step to be variable frame
rate content - i.e. the frame rate changes based on the scene
requirements.
Back in 1992 when we put together the SMPTE Task Force Report on
digital image architecture we discussed the possibility of only
refreshing portions of the scene that are changing, in much the same
way that computers only update that portion of the video output
buffer that needs to be updated. One can imagine sensors that
determine if there has been a change in the value for a sample site
since the last refresh, and only send the data for those pixels that
are changing.
Ther are MANY ways to improve imaging acquisition and display systems
that we have not even begun to explore...
Regards
Craig
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