Re: [Openexr-devel] KeyKodes (a recap)

[Ken McGaugh]

On 30 Sep 2004, at 22:53, Tom Dilligan wrote:
> Things I'm not clear on:
>
>    In the KeyCode structure: The perfOffset is in perforations or in
>    frames? I think that it should be in perfs, I've observed that 
> cineon
>    files store the perfOffset in frames, and dpx files store perfOffset
>    in perfs. If the cineon convention is chosen an additional field 
> will
>    need to be used to denote the perf offset to the actually align
>    the images.

I too feel the perfOffset should be in perfs, not inn frames.  One 
thing I'm
unclear on is if the perfOffset stored in a dpx includes the frame's
perf alignment (ie. "p1"), or is it merely just the cineon-style frame
offset multiplied by the number of perfsPerFrame?  Unfortunately I
don't have access to any dpx sequences here to test this, just cineons.

If it is the latter, then we might need an additional member to store 
this.

> Am I missing anything?

A few more things from me.  I think it would be nice if the IlmImf 
library supplied
routines (or methods) for looking up the film manufacturer code and 
film type
characters from the numbers stored in the keycode.  I would also like a 
routine
to to build a human readable string of the keycode.  And I imagine it 
would
be handy to have routines to do keycode math.

Many thanks Tom for contributing to this discussion.

--Ken