Just looked at his code:
What in blazes is a "Pointeger"? Should be "Pointer"
EDIT: And there are some other things wrong in his argument-lists
in jo_read_mp1
"OutPut" is a Reference to a pointer to Short (That's an Int16, right?), so at a guess it should be "var OutPut:PInt16" or something
in jo_readBits
first argument should be "const data:PByte"
and nevermind that when porting C/C++-code you should use the CTypes-Unit with its C-types provided