Bug#537906: Workaround available
I hit the same problem, which is that synfig is passing options to
ffmpeg which ffmpeg doesn't understand, namely -loop -hq -title blah.
Probably a previous version of ffmpeg understood these options, but
the latest one appears not to. The proper fix is therefore to update
synfig to use the correct options for ffmpeg.
In the meantime, I wrote a python script called ffmpeg which you could
keep somewhere on your path ahead of /usr/bin. It simply strips out
the bogus options and invokes the real ffmpeg.
Yes I know it's a bit of a dodgy solution, but needs must ...
# ffmpeg - a work-around for synfig to filter out the bogus arguments that
# get passed in when rendering
original_args = sys.argv
new_args = 
while len(original_args) > 0:
arg = original_args.pop(0)
if arg == "-loop" or arg == "-hq":
elif arg == "-title":