Fix for both 'ffmpeg_set_outputfile: permission denied' errors in log (3/min) and duplicate movie files in /var/lib/motion

[u2n]

From a side note in this thread two months ago, the fix was found to be the addition of the following line to motion.conf:

movie_duplicate_frames off

Current documentation states, "Users should never use this option...," which leads one to the (false) assumption that off is the default.

Or it may be that off is the original default and it gets switched on during initial or later config changes? Either way, in trying to debug just the error messages, the guide tends to lead one away from this setting - which is the source of the problem!

So guess I'm asking whether it's better to leave the behavior as-is and modify the guide text to something like:

"If permission errors are seen in the log, or files appear unexpectedly in /var/lib/motion, set this option to off."

Or leave the guide text as-is and modify the code so that this setting remains off in all cases unless explicitly enabled?

Lots of posts around the net (many, but not all, also running some version of debian) attest to the trouble with this. So it would seem that some action is indicated.

Offered as a suggestion, as always, and with appreciation for the work all this takes.