I had not put the tarball in. I repeated everything but now I have a
crash. I attach the cin5.log. Maybe the tarball of ffmpeg4.4 and
related patches should be removed?
Yeah,it seems so (because it tries to reuse ffmpeg-4.4 patches.
patch -d ffmpeg* -p1 < src/ffmpeg-4.4.patch0
Be sure to check configure.ac for correct ffmpeg version!