Re: [Openexr-devel] Long Channel Names

[Paul Schneider]

You're talking about channel names, not file names, right?  That's got 
nothing to do with FSSpecs.  The EXR format was actually designed on 
the SGI and ported to the Mac later, so there aren't any Mac 
anachronisms in the format (hopefully not too many unix-isms either).  
32 is just a commonly used number for "string that probably isn't more 
than one word".

Lee, if you change the length of the fixed-size name in your build of 
exrlib, I would expect that other software would crash when trying to 
read your non-standard files.  The EXR format allows you to add 
arbitrary attributes to the file's header, including string attributes 
of arbitrary length.  Could your driver encode the information you need 
in string attributes, rather than channel names?  Perhaps you could use 
some kind of scheme where your channel names are "1", "2", etc, and 
there is a string attribute for each channel with the real name.  See 
ImfStringAttribute.h for more information.

- Paul

On Friday, August 15, 2003, at 07:13 AM, Darrin Cardani wrote:

> At 2:54 PM +0100 8/15/03, Lee Kerley wrote:
> > I'm new to OpenEXR development, but I have a display driver for prman 
> > that writes out EXR files.  The problem is that when I output 
> > secondary outputs from my prman render the name of the channel get's 
> > quite long.  I've noticed in the code that there is a limit of 32 
> > characters.  Is there any reason why this maximum name length is so 
> > short. I accept that in most circumstances that a channel name would 
> > normally be quite short, but in thius situation I need it to be 
> > longer.  I have altered the size of SIZE define in ImfName.h to 1024, 
> > in my own build, but would like to request that this change be 
> > included in further releases of OpenEXR.
> >
> > On a more immediate note, are there any implications with me changing 
> > this variable to 1024 as opposed to it's default setting of 32?
>
> I'm guessing this is an artifact of the Mac OS FSSpec structure which 
> is used to specify a file. Newer versions of the OS (OS 9 and above, I 
> believe) can support longer file names, but there's still a lot of 
> code out there using the old structures. So the obvious consequence is 
> that if you change it, there's a chance that you won't be able to use 
> those files on a Mac.
>
> Darrin
> --
> Darrin Cardani - address@hidden
> President, Buena Software, Inc.
> <http://www.buena.com/>
> Video, Image and Audio Processing Development
>
>
> _______________________________________________
> Openexr-devel mailing list
> address@hidden
> http://mail.nongnu.org/mailman/listinfo/openexr-devel