How to convert the level values to db values ?

To convert the audio levels you have to know the codec chip gives a logarithmic hex value,

in the SNMP MIB table or in the Status report you will get the decimal value,
to convert it to dbFS it works in the following way:

(hex)

0000  (decimal = 0) = 

2000 (decimal = 8192) =  -12 dbFS

4000 (dezimal = 16384) = - 6 dbFS

7FFF (decimal = 32767) =  0 dbFS

That means:

(db)    decimal value

-96 = 2*0

-84 = 2

-72 = 2*2

-61 = 2*2*2

-45 = 2*2*2*2

-39 = 2*2*2*2*2

-33 = 2*2*2*2*2*2

-27 = 2*2*2*2*2*2*2

-24 = 2*2*2*2*2*2*2*2

-21 = 2*2*2*2*2*2*2*2*2

-18 = 2*2*2*2*2*2*2*2*2*2

-15 = 2*2*2*2*2*2*2*2*2*2*2

-12 = 2*2*2*2*2*2*2*2*2*2*2*2

-9   = 2*2*2*2*2*2*2*2*2*2*2*2*2

-6   = 2*2*2*2*2*2*2*2*2*2*2*2*2*2

-3   = 2*2*2*2*2*2*2*2*2*2*2*2*2*2*2