Here's the best way I've found:
Determine the manufacturer code and media type of the media. On Linux, I used
cdrecord
dev=XXX -atip | grep -i 'manufacturer\|media type'
, whereXXX
is the code for the Blu-ray burner as listed bycdrecord -scanbus
.Look up the manufacturer and media type codes at http://www.blu-raydisc.info/licensee-list/discmanuid-licenseelist.php . The table on that site identifies "recording type" (i.e. HTL or LTH) and also write speed from these codes.