Vaiva Kazanaviciute

You can write chops to a .wav file using ROP Channel Output CHOP node, and then play that .wav as an audio file.
List of supported chop formats: https://www.sidefx.com/docs/houdini/io/formats/channel_formats.html [www.sidefx.com]

Also I would give a try using `op:/path/to/your/chop` syntax in the Audio Filename field.
Though I doubt that it will work, since mplay (the flipbook player) is a separate process from Houdini, so most likely it won't be aware of any nodes there.
Especially since the same mplay process can be used by multiple different Houdini processes simultaneously.

If your collisions are handled by a popsolver, there are options in the Collision Behavior tab of the popsolver, to add prim and UV attributes on hit.
With those attributes you can sample any attrib from the hit surface using primuv function in VEX: https://www.sidefx.com/docs/houdini/vex/functions/primuv.html [www.sidefx.com]

From `hython --help`:
"""
-j arg : sets HOUDINI_MAXTHREADS to the given value;
arg is the max number of threads
"""
Which implies that HOUDINI_MAXTHREADS env var works for hython as well.

You can check the number of threads from inside hython using `hou.maxThreads()`.
Also there's `hou.setMaxThreads(max_threads)`, but according to docs, there are some limitations.

https://www.sidefx.com/docs/houdini/hom/hou/maxThreads.html [www.sidefx.com]
https://www.sidefx.com/docs/houdini/hom/hou/setMaxThreads.html [www.sidefx.com]