Re: [Openexr-devel] Re: [Openexr] KeyKode offsets

[Ken McGaugh]

Kevin Wheatley wrote:
> Ken McGaugh wrote:
>
> > When you say "perf offset" above, are you talking about this second number
> > Thomas suggests, or are you just referring to the existing perf offset
> > number already in Florian's proposed KeyCode class?  Should we add another
> > offset field, and if so what should we call it?
>
>
> From a scanned image pont of view there is only one perf offset that
> makes sense to me, the one corresponding to the frame, relative to the
> nearest barcode position. As the perf offset needs dividing to get the
> frame offset, I think a perfsPerFrame attribute would work reasonably
> well, with a default assumption of '4' in its absence, either that or
> you encode a filmFormat and then have a separate
> filmFormat->perfsPerFrame conversion table, but that is a step removed
> from the real facts so I'm less inclined towards it, for instance who
> would care that its Techniscope, but knowing it is 2 perfs per frame
> helps to locate the frame.

OK, so how about this.  We use Florian's KeyCode attribute and add to it
a perfsPerFrame() member.  We then leave "filmFormat" as a seperate string
attribute so that it can be as flexible as needs be.

I would aso suggest having the perfsPerFrame() default to 0 and leave the
interpretation of that to the the software reading the keycode (with the
assumption that it would be 4 in most all cases).

Sound good?

--Ken