[opendtv] Re: Production Codecs

  • From: dan.grimes@xxxxxxxx
  • To: opendtv@xxxxxxxxxxxxx
  • Date: Mon, 14 Jul 2008 10:48:13 -0700

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.

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.

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?

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.

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

Dan






Craig Birkmaier <craig@xxxxxxxxx> 
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07/14/2008 06:26 AM
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[opendtv] Re: Production Codecs






I would say that your best choices are DNxHD and AVC-Intra. There are 
several other codecs in QuickTime that may be useful for specific 
tasks, but I would recommend using a lightly compressed, frame based 
codec as your house format.

JPEG-2000 is also very interesting, as the sub band nature "could" 
allow for partial decoding for proxy and low bandwidth networked 
viewing of files without needing to deal with the full HD quality and 
bit rate requirements. Unfortunately I am not aware of any commercial 
products that let you do this currently.

As for formats, 720@60P is my preference if you cannot use 1080@60P. 
You can convert 720@60P to 1080@30i with very little loss of quality. 
By this I mean lower horizontal detail; you will lose some vertical 
detail when interlacing to 1080i.

I do not know of any limitation of 720@60P as a mastering format, 
sans one. 1080i can carry more horizontal detail, but it offers less 
vertical detail and you must deal with interlace issue when 
re-encoding to other formats.

 From your description, it looks like the only output that would 
require 1080i is for PBS. Given this you would be better off using 
720@60P as your mastering format for everything else, and the quality 
difference for 1080i will be minimal...after mission encoding, which 
will take away most of the extra horizontal detail anyway.

Regards
Craig



 
 
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