[Tig] ASC CDL in the DPX header

Jim Houston jdhouston at earthlink.net
Wed Oct 7 06:57:11 BST 2009


I don't think that CDL belongs in headers of files.
There are too many files to update if a change is made and that
process is slow.

Metadata shouldn't be replicated needlessly because it is then hard
to keep it all up to date.

The choice to have CDL available in an EDL, ALE, or XML file that
oversees a sequence of images is exactly the right place for those CDL
values to be.  It does require keeping track of your EDL and changes  
to a timeline,
but that is what editors do.  An XML file can be used to cover all the  
files in
a directory, or you can use reference links to an XML file as well.

It isn't a question of how many bytes are in the data to be put into a  
header,
it is the seek and open time for an application to go through all the  
file
headers to find the spots where it changes.   Load the file headers
for a movie,  say 140,000 frames, and see how long that takes.
It will be obvious why metadata that applies to large sequences of
images belongs elsewhere.


Jim Houston
co-author of ASC-CDL documents.




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