About fourcc usage, I am not sure we can gain a lot here because there is some problem to take into account. Comparing 4 characters is always faster than comparing string of unknown size but to be very fast, we must compare the 4 bytes simultaneously (one 32bits value). However, in this case, we must define the endianness of the protocol (big endian is better, like any portable network protocol (TCP, IP,...) else we will have PC clients incompatible with MAC one (ABCD on PC is displayed DCBA on mac). Only a onecc can solve the problem without conversion :)

Uhm, fourcc, four character code, stress on _character_ (one byte), i e no
endianness...

/J