Thanks for the quick reply!
If I set an in & outpoint using mplayer, when I switch to mpv, it starts at mplayer's outpoint & just keeps playing, with no outpoint. Then when I switch back to mplayer, it starts & stops at the original in & outpoints.
If I set points in mpv, it just keeps playing. If I close the video, then reopen with mpv, it starts at the outpoint & just keeps playing, with no outpoint. If I then open in mplayer, it starts at some arbitrary point, then stops at a later point... like it slides the in & outpoints forward,
Just strange that it can't be duplicated.
Any ideas what could cause something like this, on my computer? Or in my config of smplayer?
I tried updating to the latest version of mpv... still the same.