[opendtv] Re: Some results - 1080p @ 60 is Next?

  • From: Craig Birkmaier <craig@xxxxxxxxx>
  • To: opendtv@xxxxxxxxxxxxx
  • Date: Tue, 15 May 2007 11:04:55 -0400

At 7:23 AM -0400 5/15/07, Tom Barry wrote:
I was NOT arguing for a single common image resolution or format. You might even remember that I have sometimes suggested on this list that codecs themselves continuously vary the resolution based upon bit rate budgets. The idea of a single resolution is (should be) obsolete even within a single transmission. But most codecs don't gracefully handle this idea yet.

I was also not arguing for a higher (1920x1080p) emission format. That is still not practical for most bit budgets except highdef discs. If we must use 1080i emission due to some standard then 1440x1080i is better (like BBC). And 720p is probably better yet for this once good oversampling (1080p+) cameras and equipment are available.

What I was suggesting was simply a high resolution archive format such that many different future uses of the video may be re-encoded from a good 'master'. What comes to mind is the TV shows of the early nineties or whenever that were shot in interlaced video and are fairly worthless now for highdef purposes. We have to keep in mind the syndication and re-use value of anything expensively shot now and plan for the display and distribution technology of tomorrow. We can afford the cost of the storage to do this, in multiple distributed copies.


Thanks for the clarification Tom. We are very much in agreement.

Keep in mind that we already have two 1080P emission formats 24P and 30P. What we should be rid of is the 30i format - 720@60P is clearly superior for fast action and fits the available channel bit budgets better.

Even 1920 x 1080 may not be sufficient for the kind of archival format you describe. If the source is 24P we can do it today. There were a number of demos at NAB regarding "mezzanine" encoding formats for archival purposes. The more important aspect of these formats is that they offer improved color space encoding, either 4:2:2 or 4:4:4. The 4:2:2 color encoding is not much of an improvement as it only gives you additional color detail in the horizontal axis - this was useful for interlaced formats, but not for progressive formats

4:2:0 is the equivalent for progressive formats, but is often considered to be lower than 4:2:2. In fact, this is just a quirk in the notation format. In essence it is half vertical and half horizontal color resolution. 4:2:2 increases the vertical color resolution storing it for every line - you might as well go to full 4:4:4 as there will be little impact on the encoded bit rate.

The other aspect of the mezzanine formats is that they are typically 10 bit or more for luminance.

Hollywood wants to move to 4K x 2k, both for archival purposes and for theatrical exhibition. I think that this is likely to be a more important market than 1920 x 1080@60P for TV applications.

Regards
Craig


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