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

[Ken McGaugh]

Florian wrote:
>
>Given the replies to my last mail, I'll try again:  Please vote for one of
>the following:
>
>     A) DPX-style film edge codes, as listed in section 6.1 of SMPTE 268M,
>        "File Format for Digital Moving-Picture Exchange", but with two
>        additional fields (perfs per frame, perfs per count).
>
>         film manufacturer ID code
>         film type
>         prefix
>         count
>         offset in perfs
>         perfs per frame (default value: 4)
>         perfs per count (default value: 64)
>
>        The "perfs per frame" field is necessary to convert the "offset
>        in perfs" to a frame number (count + frame).  This covers the 35mm
>        3-perf format.
>        In order to cover 65mm formats, where the count increments every
>        80 or 120 fields, an additional "perfs per count" field is needed
>        in order to determine the number of frames between two given film
>        edge codes.
>

If we limit our definition of the keycode to be that which can uniquely
identify a frame on film, then we don't need the "perfs per count" above.

Because of production pressures, I've already implemented the above but
without the "perfs per count", so obviously I'm biased against it. :)

But if this is what everybody wants I'll convert all our recent scans.

--Ken