Sample rate in chops is not always tied to the frames pr second you operate in. If you are sampling audio for example you might want higher sample rates. But i agree it could at least be $FPS. I put this in my houdini.env: “`FPS = 25 HOUDINI_CHOP_UNITS = frames“` This sets FPS in your hip to 25(i dont do any film work), sets Sample Rate in chops to 25 and Unit in chops to Frames. I always mess up when its set to Seconds(default)