1# <mp4 root> | mp4_path(".moov.trak[1]") -> box
2# box -> | mp4_path -> ".moov.trak[1]"
3# box -> | mp4_path(<mp4 root>) -> ".moov.trak[1]"
4def mp4_path(p):
5    _decode_value(
6        ( if format != "mp4" then error("not mp4 format") end
7        | tree_path(.boxes; .type; p)
8        )
9    );
10def mp4_path:
11    ( . as $c
12    | format_root
13    | mp4_path($c)
14    );