Rendering to .avi doesn't work

I have made several short animations in 0.64.0 (in Windows 7, 64-bit) which are ready for export to AVI format. However, after I started the rendering, I noticed the following error message (in red) in the command window:

Unrecognized option ‘loop_input’.
Error splitting the argument list: Option not found

The main window then said “render complete” but no AVI file is to be found.

I have downloaded the 64-bit static version (dated 26 September) of ffmpeg, so I doubt it is ffmpeg’s fault. Can someone tell me what is going wrong?

Ffmpeg has changed its CLI option in several occasions, it is quite hard to keep those command options to work on all versions and platforms.

In that case, what would be the fastest way to turn the synfig files into videos? The conversion to png works but I don’t have the time to play with ffmpeg to convert the mess.

Render to png sequence, join them using Avidemux.