After selecting filters like deblocking, sharpening, denoising, etc, MPlayer was restarted and playback continued. I then closed SMPlayer, and later on played another file.
What I expected: the filters I selected were still active.
What actually happened: all the filters were reset to their defaults (off).
I can see the logic in not persisting filters, since video files are not all the same. However it would be nice to have an option to persist them (like we can with postprocessing) for those like me who do want certain filters to persist.
I was able to work around this by
-using Process Explorer to fetch the cmdline for mplayer.exe during normal playback and again with filters enabled
-manually comparing the strings to find the diff
-removing the overhead like the process ID and realizing that the vpf-add options are the options that can be added to the MPlayer options in the Advanced options tab
Please consider adding persistence to those options