Re: [Openexr-devel] Maximum channel name length

[Florian Kainz]

Yes, this behavior is to be expected.  Channel and attribute
names are at most 31 characters long.  We could raise or remove
the limit, but this would create a compatibility problem; older
versions of the IlmImf library would not be able to read files
where one or more channels have names that are longer than 31
characters.

If enough people feel that backwards compatibility is less of a
concern than truncated names, then we'll just change the library
to allow long names.

Florian



Ton Roosendaal wrote:
> Hi,
>
> It looks like channel names in files are truncated to be 31 chars (plus  
> trailing zero) maximum. That seems to be defined in ImfName.h.
>
> In Blender we make use of the features as described in  
> ImfChannelList.h, for image files with many channels to group them into  
> nested layers. Unfortunately the maximum of 32 chars seems to be for  
> the total name, not for the individual nexted parts.
>
> For example; in Blender you can define per render command:
> - Layers (geometry based, like foreground/background)
>   - Passes (shading based, like per Lamp or Combined)
>     - Channels (R,G,B,A or X,Y,Z, etc)
>
> I get errors reading back files with a channel named like:
>
> Characters_and_platform.Combined.R
>
> Which is just 34 characters...
> So, is this limited naming behaviour as expected?
>
> Thanks,
>
> -Ton-
>
> ------------------------------------------------------------------------ --
> Ton Roosendaal  Blender Foundation address@hidden  http://www.blender.org
>
>
>
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