how to work out the pssh when not shown in the mpd

[rifleman1202]

In my case, this is the PSSH that EME logger gave me which obviously doesn't look right, so I converted from Base64 to Hex and trying to extract the PSSH Box based on ridibunda's explanation:

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

if the wv pssh is before the pr wv pssh then you can use this method to extract it.
take the first 8 characters in hex - which is the pssh box size padded to 8 characters
"00000040"
convert that hex value (40) to decimal and you get 64, so the total size of the pssh box is 64 bytes which is 128 characters in hex.
take the first 128 characters from the hex output and then convert it to base64 to get your wv pssh.

wv pssh hex: 000000407073736800000000EDEF8BA979D64ACEA3C827DCD51D21ED000000202218594F55545542453A6438313561306639366330323638323848E3DC959B06
wv pssh base64:
AAAAQHBzc2gAAAAA7e+LqXnWSs6jyCfc1R0h7QAAACAiGFlPVVRVQkU6ZDgxNWEwZjk2YzAyNjgyOEjj3JWbBg==

Thank you very much ElCap for responding and explaining how it works, I got it now.