[opendtv] Re: Production Codecs

  • From: Craig Birkmaier <craig@xxxxxxxxx>
  • To: opendtv@xxxxxxxxxxxxx
  • Date: Tue, 15 Jul 2008 00:18:54 -0400

At 10:48 AM -0700 7/14/08, dan.grimes@xxxxxxxx wrote:
An Avid engineer told me that other formats will not mix with 720@60P because it is essentially a unique frame rate. Thus, 1080@xxxxxx (59.94 fields) would need to be transcoded before it can be used in an Avid project that is specified at the 720@60P rate. In fact, probably any format will need to be transcoded.

Rubbish.

The reality is that NOBODY is using 24P, 30P or 60P, although some products can operate at these frame rates. All commercial products for the U.S. market that I am aware of operate at 23.976, 29.97 and 59.94 either progressive or interlaced, as specified in the infamous Table 3 of the ATSC standard.

I'm not certain how Avid handles it now, but with Final Cut Pro you can intermix sources at different spatial and temporal resolutions:

http://www.apple.com/finalcutstudio/finalcutpro/support.html

Open format Timeline

The new open format Timeline in Final Cut Pro 6 lets you mix and match source material in a wide range of formats and even different frame rates. Just drag your footage into the Timeline. Freely edit a combination of HD and SD, including NTSC and PAL, all in real time. Final Cut Pro 6 offers real-time scaling and playback for video in various camera-native formats as well as Apple ProRes 422.


We might be able to transcode 720@60P material to 1080i for PBS. They have some very limiting rules that allow only certain transcoding and have often kept our material from airing because of perceived quality issues even when better than some of the material they have produced or used directly from PBS. But over all, unless we have some terrible artifacts, this should work.

Don't tell them it was shot in 720P.

There was a time when PBS ( and Discovery) would not accept anything output from a nonlinear editing system.

Because so much of our distribution will be through highly compressed media, the 720@60P makes sense. So then that might open up the codec possibilities, wouldn't you think?

Apples and oranges. Just about everything is over-compressed in emission channels. That's not your problem as they probably DO NOT want your programs delivered at emission coding rates. For your in house format you should use lightly compressed, frame based codecs such as those you listed (or you could use Apple's Pro Res 422). The choice may have more to do with what Avid supports since you want to stay with the Media Composer.


I have worked with JPEG2000 but not on at a post-production level. I don't know if it has been implemented on the production level or not.


It is being used in Hollywood, mostly for D-Cinema applications.


Which formats work well in an MXF (and BXF?) wrapper?


There is growing support for MXF, but MXF is not widely supported outside of the world where the SMPTE still holds some sway. It is used in many of the new professional recording formats from Sony and Panasonic. There is some useful information here:

http://en.wikipedia.org/wiki/MXF

XML is being used far more than MXF for metadata applications. The SMPTE is working on a schema for interchange between XML and MXF.

Avid created OMF and worked with SMPTE on MXF - I believe they use MXF with their DNxHD codec, and MXF is fully supported in Media Composer, so you should not have any problems.

Regards
Craig


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