pchcps - convert frequency to octave.pitch-class
pchcps (frequency)
Given a frequency in Hz (cycles per second), pchcps returns that value expressed in ``octave.pitch-class'' (oct.pc) notation. oct.pc is a way to use standard "western" keyboard notes without having to look up the pitch-frequency conversion. It works by arbitrarily assigning the octave of middle-C to 8.00. Any semitone above middle-C is added as a "hundredth" to the left of the decimal point, i.e. 8.01 is the C# just above middle-C, 8.02 is the D, 8.03 is the D# (Eb), etc. up to 8.12, which is equivalent to 9.00. 9.01 is then the C# one octave and a semitone abouve midddle-C.
The fun thing about this notation is that you are not limited to keyboard-notes. A pitch specification of 7.07542389 will select a frequency that is somewhere about half-way between the G (7.07) and Ab (7.08) just below middle-C. Different RTcmix instruments will require the pitch or frequency to be specified in different ways, although the scorefile commands cpspch, octcps or other related commands can do most necessary conversions.
See the other format conversion routines for more information.