(System: Ubuntu 16.04)I tried Building using the build.sh script as well as building individual modules seperately .
Below is the description of the error
/synfig/synfig-core/src/modules/mod_libavcodec/trgt_av.cpp:199:6: error: reference to ‘AVPixelFormat’ is ambiguous
synfig/synfig-core/src/modules/mod_libavcodec/trgt_av.cpp:209:53: error: ‘AVStream {aka struct AVStream}’ has no member named ‘codecpar’
Hmmm… it looks like we have lost compatibility with old FFmpeg.
Please open file autobuild/build.sh and change on line 175 from
--with-libavcodec
to
--without-libavcodec
After that please try to do rebuild again.