FFMpeg set language as Unknown or unspecified in a QuickTime MOV
-map 0:v \
-map 0:1 -metadata:s:a:0 language=zxx \
-map 0:2 -metadata:s:a:1 language=eng \
-map 0:3 -metadata:s:a:2 language=fra \
-map 0:4 -metadata:s:a:3 language=kin