What is the current situation w.r.t. multi-part exr generation in Houdini (mantra, primarily, but others as well)? I can't seem to find any information on using this feature, and it's been a while since OpenExr-2.0…

Preliminary investigations by some Nuke types have seen some significant speedups with the more optimal loading this provides.

any news on this? It's been while so there might be some progress :-)

In October 2019, there was an experimental OpenEXR driver added to H18.0. You can enable this by setting HOUDINI_OIIO_EXR=1.

https://www.sidefx.com/changelog/Main/?journal=18.0&categories=5&body=openexr&version=&build_0=&build_1=&show_versions=on&show_compatibility=on&items_per_page= [www.sidefx.com]

When Houdini reads a multi-part image, the new driver will be used automatically. But for writing, you'll have to set the environment variable.

Please send feedback on how this works for you.

When Houdini reads a multi-part image, the new driver will be used automatically. But for writing, you'll have to set the environment variable.

Is this somehow automatically set up for Karma Render Nodes?

I just installed ffmpeg (June 20th version) and tried converting some exrs to another format. But all attempts I get errors of “…multipart is not implemented….”

However if I take those exrs and create a new series of exrs from a Houdini Cops with a Rop File Output node and then in ffmpeg I am able to convert the exrs no problem.

It seems the output in Karma for exrs is different than a Rop File Output.

Karma always outputs multipart exrs. I think cops is still non-multipart for writes unless you change an env var as mark said. (I'm not sure if that variable applies everywhere in Houdini or just for Mantra)

Thanks for the confirm jsmack.

A little further information. Karma has a command line option <tt>–exrmode (mode)</tt>.
- If mode is 1 (default on all platforms except OSX), karma will output multi-part EXRs
- If mode is 0, karma will output flat EXRs (old style)
- If mode is anything else (-1 for example), the HOUDINI_OIIO_EXR variable will be used to select