Re: [Openexr-devel] extension mandate for stereo EXRs?

[Florian Kainz]

The Multi-View OpenEXR document (see OpenEXR CVS repository) by
Peter Hillman and Matt Welford suggests that you should allow your
users to save stereo images with a .sxr extension (see below).

The .sxr extension allows software (and people) to identify stereo
images by looking at the file name.  A potential disadvantage of
the .sxr extension is that some application programs may assume
that all OpenEXR files have a .exr extension.  Those programs would
fail to open .sxr images even though they could read the files just
fine if they tried.

Florian

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    File Name Extension Support

    Users may wish to save multi-view OpenEXR files with a file
    name extension other than the commonly used .exr, for example,
    .sxr for Stereo eXR, or .mxr for Multi-view eXR. The 3-letter
    extension space is crowded, but SXR and MXR are not heavily
    used. Either or both of these may become a standard for
    multi-view OpenEXR files.

    Meanwhile, it is recommended that software vendors provide a
    mechanism allowing users to identify which file name extensions
    they will employ for multi-view OpenEXR files. For example,
    software may understand the environment variable

        MULTIVIEW_EXR_EXT="SXR"

    or provide a similar facility in a configuration file or registry
    entry.  Software can then default to saving multi-view OpenEXR
    files with this extension, and also try loading files with this
    extension as OpenEXR files before resorting to brute force
    attempts to interpret the file format from the header data. If not
    specified, the default extension for multi-view OpenEXR files should
    be .exr.


Paul Miller wrote:
> I'm currently writing my stereo EXR files with an .exr extension. Should 
> I be forcing the extension to sxr when writing stereo? Currently, I 
> don't give my users control over the extension, and I have some asking 
> for the ability to name their stereo files with an .sxr extension.