The sevent sid_timesig sets the time signature for the track. a "time signature" SEvent has the following structure overlaid on the sevent structure: typedef struct { UBYTE type; /* = SID_TimeSig */ unsigned timeNSig :5, /* time sig. "numerator" is timeNSig + 1 */ timeDSig :3; /* time sig. "denominator" is 2^timeDSig:* * 0 = whole note, 1 = half note, 2 = * * quarter note,....7 = 128th note */ } STimeSig; [Implementation details. Unsigned ":n" fields are packed into n bits in the order shown, most significant bit to least significant bit. An STimeSig fits into 16 bits like any other sevent. warning: some compilers don't implement bit-packed fields properly. E.g., Lattice C pads a group of bit fields out to a LONG, which would make an STimeSig take 5-bytes! In that situation, use the bit-field constants defined below.] The field type contains the value SID_TimeSig, indicating that this sevent is a "time signature" event. The field timeNSig indicates the time signature "numerator" is timeNSig + 1, that is, 1 through 32 beats per measure. The field timeDSig indicates the time signature "denominator" is 2^(timeDSig), that is each "beat" is a 2^(-timeDSig) note (see SNote division, above). So 4/4 time is expressed as timeNSig = 3, timeDSig = 2. The default time signature is 4/4 time. Be aware that the time signature has no effect on the score's playback. Tempo is uniformly expressed in quarter notes per minute, independent of time signature. (Quarter notes per minute would equal beats per minute only if timeDSig = 2, n/4 time). Nonetheless, any program that has time signatures should put them at the beginning of each trak when creating a form smus because music editors need them. Instead of the bit-packed structure STimeSig, it might be easier to assemble data values by or-ing constants and to disassemble them by masking and shifting. In that case, use the following definitions. #define timeNMask 0xF8 /* bit mask for the timeNSig field */ #define timeNShift 3 /* shift count for timeNSig field */ #define timeDMask 0x07 /* bit mask for the timeDSig field */