Re: [Openexr-devel] keycode

[Ken McGaugh]

Kevin Wheatley wrote:
> Ken McGaugh wrote:
>
> > We want to store film keycode information in our exr's, and before I
> > decide what header attribute(s) to create for this I wanted to
> > know if anybody else is doing this already.  If so, what type and
> > names did you choose for your header attributes.
> >
> > I was hoping to embed the keycode information into one string attribute
> > rather than 5 attributes of various types is is done in DPX/cineon files.
>
>
> timecode ?
> framerate ?
> ...
>
> soon you'll end up with cut down DPX format that supports HDR and
> compression ... with a decent reference implementation.
>
> That idea sounds silly, I mean who on earth would want such a thing
> :-)

I've been researching this a bit more, and I think you are right that we
shouldn't limit ourselves.  So why don't we just use the data structures
specified in the SMPTE DPX spec as the attributes themselves.  There would
be one for motion picture information, and another for television information.

For example, the motion picture information attribute might look like this:

  struct DPXMotionPictureInfo
  {
      uint8_t    filmMfgCode[2];
      uint8_t    filmType[2];
      uint8_t    perfOffset[2];
      uint8_t    prefix[6];
      uint8_t    count[4];
      uint8_t    format[32];
      uint32_t   framePosition;
      uint32_t   sequenceLength;
      uint32_t   heldCount;
      float      frameRate;
      float      shutterAngle;
      uint8_t    frameID[32];
      uint8_t    slateInfo[100];
      uint8_t    reserved[56];
  };

  typedef TypedAttribute<DPXMotionPictureInfo> DPXMPAttribute;

In the implementation, the static type name for the attribute could be "dpxmp".

Any opinions?  Should we push for it (or something like it) to be put into
the "standard" attributes?

--Ken