In ISO/IEC 14496-15, the minimum size of a HEVCDecoderConfigurationRecord
(i.e., the contents of a hvcC box) is 23 bytes. However, the code in h265parse
checks that the size of this data is not less than 28 bytes, and it refuses to
accept caps if the check fails. The result is that standards-conformant streams
that don't carry any parameter sets in their hvcC boxes won't play.
https://bugzilla.gnome.org//show_bug.cgi?id=731783