format of data block passed to module_ident

 0   inch/onch        number of channels
 4   ibits/obits      bits per sample
 8   iform/oform      format:
                        bits 0,1: 0=linear signed
                                  1=linear unsigned
                                  2=-LAW
                                  3=Arc-log
                        bits 2,3: currently unused (for extra formats)
                        bit 4   : 0=little endian, 1=big endian
                        bit 5   : set if module should do load/save (eg for compression)
12   ifreq/ofreq      frequency (frames per second)
16   iframes/oframes  number of sample frames in file
20   iofs/oofs        offset into file of first sample
24   iftype/oftype    file type
28   iuser/ouser      user data (16 bytes)