Re: [Openexr-devel] New framesPerSecond Attribute?

[Bob Friesenhahn]

On Fri, 13 Oct 2006, Florian Kainz wrote:

> I would like propose a new "framesPerSecond" standard attribute
> for OpenEXR:
>
> The attribute defines the frame rate at which an OpenEXR image
> sequence should be played back.  All frames in a sequence should
> have this attribute, and the attribute's value should be the same
> for all frames.  If no frame rate is specified for a sequence,
> then playback software should assume 24 frames per second.
>
> The attribute's value could be represented either as a floating-
> point number or as the quotient of two integers.  A floating-point
> number would be easier to use, but it cannot represent NTSC frame
> and field rates exactly.  A quotient would be slightly less
> convenient, but all commonly used frame rates, including NTSC,
> can be represented exactly.

The SMPTE DPX format uses your 'float' scheme.  It certainly does not 
hurt to be aligned with an existing industry standard.

A more exotic approach is to represent the rate as a frame delay 
instead.  This allows for frame playback at varying rates, with the 
possibility to hold one frame for a long time.

Bob
======================================
Bob Friesenhahn
address@hidden, http://www.simplesystems.org/users/bfriesen/
GraphicsMagick Maintainer,    http://www.GraphicsMagick.org/