Testing with the new Ubuntu 20.04 LTS shows issues compiling against the OpenCV2 headers:

../ld-chroma-decoder/opticalflow.h:34:10: fatal error: opencv2/core/core.hpp: No such file or directory
34 | #include <opencv2/core/core.hpp>
| ^~~~~~~~~~~~~~~~~~~~~~~

Since the NTSC optical flow isn't functioning, the requirement to include opencv should be removed (and once reimplemented a more up-to-date header should be included instead).