Re: [Openexr-devel] keycode

[Daniel Fort]

Hi Ken,

I'm happy to see that film is still alive. As an assistant film editor 
maybe I can put in my 2 cents.

>     struct keyCode
>     {
>         char        filmMfgCode[2];
>         char        filmType[2];
>         char        perfOffset[2];
>         char        prefix[6];
>         char        count[4];
>     };

One item that seems to be missing is the film format. The perf offset 
becomes very important for 35mm 3-perf where the perf-1 foot is 21 
frames, perf-2 foot is 21 frames and the perf-3 foot is 22 frames long. 
You probably won't be too concerned with counting frames and 
incrementing frame and perf numbers, but knowing the original film 
format  is always a good thing--and there are lots of film formats from 
16mm (1-perf) through 65mm IMAX (15-perf). In addition, remember we are 
not necessarily counting in feet when using keynumbers. 16mm increments 
the key number twice in one foot.

Perfs per key number:

16mm - 20 perfs
35mm - 64 perfs
65mm - 120 perfs
> ...  In fact, the struct should probably have a member
> function for returning the entire keycode as an ascii string looking
> something like
>
>     EH 01 0594 5390 + 12
Don't forget to include the perf offset, something like:

          EH 01 0594 5390 + 12 p2

Like I said, this is necessary on formats like 35mm 3-perf but it 
should be optional on formats like 16mm, 35mm 4-perf, 35mm 8-perf, 65mm 
5-perf, etc.

--Dan