DWAA compression and level

[Carlo Giesa]

Hi there!

I'm trying to figure out how to render out dwaa compressed EXR images with Arnold through Gaffer and can't really find a lot of information about it.

So, setting the 'compression' property to 'dwaa' on the output seems to use the correct compression. But how can I control the compression level? It seems to default to 45. I tried to add a custom float attribute 'dwaCompressionLevel' (that's how it's called in the exr metadata) but this doesn't seem to have any impact.

Any idea?

Next idea would be to run a post render process that uses an image write node where the option is available. But ideally, I would like to avoid this.

Thanks,

Carlo

[John Haddon]

Hi Carlo,

My usual go-to for this sort of thing is `kick -info`, which prints out all the parameters Arnold accepts. In this case `kick -info driver_exr` doesn't give anything that looks like it could set compression level.

My second attempt was to create a `header:dwaCompressionLevel` parameter to see if I could sneak the level past Arnold and direct to OpenEXR. But although any other name works, this one always seems to be clobbered with 45 as a value, presumably by Arnold.

So I'm stumped - I'd suggest checking with Arnold support to see if there's some other way of approaching this.

Cheers...

John

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[Carlo Giesa]

Hi John!

Thanks for checking. I got an answer from Thiago on the Arnold Autodesk forum on that question:

Hi, this looks like it's the bug fixed by this OpenImageIO bugfix: https://github.com/AcademySoftwareFoundation/OpenImageIO/pull/4434

When we upgrade the OIIO used by Arnold hopefully we'll get this fix. For reference, we have the internal ticket ARNOLD-9055 for fixing this bug (hopefully by upgrading OIIO) and ARNOLD-16022 for doing the actual OIIO upgrade. If you see those in the Arnold release notes it means we think this has been fixed.

But this doesn't really tell me (or I don't get it) how this is supposed to work once the OIIO version used by Arnold gets updated.

Greets,

Carlo

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[John Haddon]

Oh, interesting! Looking at that snippet of OIIO source was useful. So for now it seems to work if you add an integer called `header:CompressionQuality`. And I think once Arnold upgrades to include that fix, you'll be able to make a float called `header:openexr:dwaCompressionLevel` instead.

Hope that helps...

Cheers...

John

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[Carlo Giesa]

Hey John!

That did the trick! Thanks for the hint. Let's see how that works once Arnold updates its OIIO version. If I get this correctly, this is part of OIIO since 3.0.0.0, right?

Greets,

Carlo

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