Do not fail when unable to detect the FFMPEG version, like windows.

CMakeLists.txt

@@ -261,16 +261,16 @@ if(FFmpeg_FOUND)
             set(FFVER_OK FALSE)
         endif()
     endif()
+
+    if(NOT FFVER_OK AND NOT APPLE)  # unable to detect on version on MacOS < 11.0
+        message(FATAL_ERROR "FFmpeg version is too old, 3.2 is required" )
+    endif()
 endif()
 
 if(NOT FFmpeg_FOUND)
     message(FATAL_ERROR "FFmpeg was not found" )
 endif()
 
-if(NOT FFVER_OK)
-    message(FATAL_ERROR "FFmpeg version is too old, 3.2 is required" )
-endif()
-
 if(WIN32)
     message("Can not detect FFmpeg version, at least the 3.2 is required" )
 endif()