[opendtv] Re: Production Codecs

  • From: "Richard C. Ramsden" <ramsden@xxxxxxxxxxx>
  • To: opendtv@xxxxxxxxxxxxx
  • Date: Wed, 16 Jul 2008 02:29:01 -0400

There is a hidden standard for dealing with 720p@xxxxx
It's exactly the same as 29.97. 29.97 is 59.94 fields/sec. Treat each progressive frame as an interlaced field. Drop 4 frames where in 29.97 you'd drop 4 fields. This method is used in all Harris (my employer) equipment. It's obvious, it works, and it doesn't break when you down convert.
For 23.98, I expect that some application of 3:2 pull down can resolve how drop frame can be applied.
SMPTE specs aren't very good these days. There's more that's not there, or vaguely spec'd than that is well defined. MXF is a nightmare. What actually works is an agreement by the major players on what the spec means to them. 

Rich

Tom Barry wrote:

dan.grimes@xxxxxxxx wrote:

> I would prefer to work in 1920x1080 rather than a "thin" raster (Avid
> used that term for formats other than 1920x1080, if I understood them
> correctly). I don't think we can afford 1080@60P so will likely produce 
> in 30P or 60i.
>
> We can work in 720@60P if need be.  But I hear that it has unique
> qualities and not intermixable with other media.

It would probably be good to get a dialog going on this one.
What qualities have you heard are problematic with 720@60p? For instance, are there standards for handling drop frame?
IMHO if you work in 30p you will never have smooth motion as other things become 60p, including most new displays. If you work in interlaced format now you may be stuck there forever. And again, almost all new displays are progressive.
So I personally prefer 720p/60. Once you solve the problems you will also be more ready for 1080p/60 which will eventually be used, though likely unneeded for quite awhile. 

- Tom



Anyone interested in talking about production codecs?
I would like to consider using a "house" video production codec for our new facility. The way I see it, the following are possibilities: 

AVC-Intra
DVCProHD
XDCam-HD
XDCam-EX
DNxHD
JPEG-2000 (?)

Any others to consider?

Some information on our application:
-We want to be as file based as possible with solid-state media from the field and direct outputs whenever possible (see below). -We would like to produce in 720P and 1080i, depending on the client, 1080i for airing on PBS and 720P for all formats requiring deep encoding. -Our outputs include DVD (mostly standard DVDs but blu-ray in the future, I suppose), internet streaming, submission to an SD network (OSTN) in MPEG-2, an SD cable channel on Cox (live and automated output, with the hopes of maybe an HD channel in the future), and internet VOD. 
-We edit using Avid Media Composer and do not plan to change.
I would prefer to work in 1920x1080 rather than a "thin" raster (Avid used that term for formats other than 1920x1080, if I understood them correctly). I don't think we can afford 1080@60P so will likely produce in 30P or 60i. We can work in 720@60P if need be. But I hear that it has unique qualities and not intermixable with other media. 

So what are the brain-trust's thoughts and experiences?

Dan







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