author  Alexander Simm

The partition entry ID indicates the partition entry in the FD item
information box. A zero value indicates that no partition entry is
associated with this sample entry, e.g., for FDT. If the corresponding FD
hint track contains only overhead data this value should indicate the
partition entry whose overhead data is in question.
return  the partition entry ID

The FEC overhead is a floating point value indicating the percentage
protection overhead used by the hint sample(s). The intention of
providing this value is to provide characteristics to help a server
select a session group (and corresponding FD hint tracks). If the
corresponding FD hint track contains only overhead data this value should
indicate the protection overhead achieved by using all FD hint tracks in
a session group up to the FD hint track in question.
return  the FEC overhead