Hiiiii,
           I am Jitendra,Comm.Engg. making Reed-Solomon Codec using specs
of ITU-J.83 Annex-B.
Specs are :
n=128,k=122,
under GF(128),
7-bit symbol, 
Generator Polynomial : 
G(x)=(x+alpha^1)(x+alpha^2)(x+alpha^3)(x+alpha^4)(x+alpha^5);
As per the standard I come up with a encoder, But I didnt have any
reference to verify/check my codeword. In matlab, RS functions are taking
n and k parameters such that n-k differece must be +ve even integer.
Here while encoding, we have to set n=127.and that's is max value for n
under GF(128) for 7-bit symbol.
After Generating 127 symbols CW, 128th symbol is generated by evaluating
CW on 6th power alpha.

Decoder side, I calculated 5 syndromes by evaluating 127-symbol CW at
alpha,...alpha^5 and 6th syndromes by evaluating 128-symbol CW at
alpha^6.
But I am not able to decode it.

If you have any usefull information on this let
me know. 

Thanks,
Jitendra.
jitendra.sn@gmail.com
jitendra_nalawade@yahoo.co.in