Description
string 
bzcompress ( string source [, int blocksize [, int workfactor]])
     bzcompress() compresses the
     source string and returns it as bzip2
     encoded data.
    
     The optional parameter blocksize specifies
     the blocksize used during compression and should be a number from
     1 to 9 with 9 giving the best compression, but using more
     resources to do so. blocksize defaults to
     4.
    
     The optional parameter workfactor controls
     how the compression phase behaves when presented with worst case,
     highly repetitive, input data.  The value can be between 0 and
     250 with 0 being a special case and 30 being the default
     value. Regardless of the workfactor, the
     generated output is the same.