freq -- translate selected Humdrum pitch-related representations to frequency


freq [-p n] [-tx] [inputfile ...] [> outputfile"]


The freq command transforms various pitch-related inputs to corresponding frequency representations. It outputs one or more Humdrum **freq spines containing numerical values (in hertz) corresponding to the fundamental frequency for pitch-related input tokens. For example, the **pitch token "C4" is transformed to 261.63 (hertz).

The freq command is able to translate any of the pitch-related representations listed below. In each case, a tuning standard of A4 equals 440 hertz is assumed. For descriptions of the various input representations (including **freq) refer to Section 2 (Representation Reference) of this reference manual.

It is recommended that output files produced using the freq command should be given names with the distinguishing `"' extension.

**cbrcritical band rate (in equivalent rectangular bandwidth units)
**centshundredths of a semitone with respect to middle C=0 (e.g. 1200 equals C5)
**cochocochlear coordinates (in millimeters)
**freqfundamental frequency (in hertz)
**fretfretted-instrument pitch tablature
**kerncore pitch/duration representation
**MIDIMusic Instrument Digital Interface tablature
**pitchAmerican National Standards Institute pitch notation (e.g. "A#4")
**semitsequal-tempered semitones with respect to middle C=0 (e.g. -12 equals C3)
**solfgFrench solfège system (fixed `doh')
**specCspectral centroid (in hertz)
**TonhGerman pitch system
Input representations processed by freq.


The freq command provides the following options:
-hdisplays a help screen summarizing the command syntax
-p noutput precision of n decimal places
-tsuppresses printing of all but the first note of a group of tied **kern notes
-xsuppresses printing of non-frequency signifiers
Options are specified in the command line.

The -p option can be used to set the precision of the output values to n decimal places. The default precision is two decimal places. Note that freq is able to process **freq as input; this feature allows the user to round-off existing **freq data to a specified precision.

The -t option ensures that only a single output value is given for tied **kern notes; the output coincides with the first note of the tie.

In the default operation, freq outputs non-pitch-related signifiers in addition to the frequency value. For example, the **pitch token "A6zzz" will result in the output "1760.00zzz" -- that is, after translating A6 to 1760.00 hertz, the "zzz" signifiers are retained in the output. For some applications, echoing non-pitch-related signifiers in the output is useful. However, in other situations, the result can prove confusing -- especially, when the non-pitch-related signifiers are numbers. Consider the case of the **kern token "8aaa"; after translating `aaa' to 1760.00 hertz, the non-pitch-related signifier `8' will also be output, hence the value 81760.00 -- which will undoubtedly cause confusion. The -x option is useful for eliminating non-pitch-related signifiers from the output. For most **kern inputs, the -x option is recommended.


The following example illustrates the use of freq. The input contains six pitch-related spines -- one of which (**deg) cannot be processed by freq. In addition, there are two non-pitch-related spines (**embell and **metpos).
!! `freq' example.
4a-]D4/48/ /52/128.11C3ct
.D4 F4/-52/237.33 6.4C3 Es3ct
rG4.r1rH2 D3.
Executing the command

freq -tx input > output"

produces the following result:

!! `freq' example.
.293.66130.81 164.8112340.92130.81ct
.293.66 349.23.23289.24 234.47130.81 155.56ct
r392.00.r1r123.47 146.83.
Both processed and unprocessed spines are output. Notice that the tied note at the beginning of measure 2 in the **kern spine has been rendered as a single note rather than as two notes (due to the -t option). Also notice that the non-pitch-related signifiers (e.g. foo) in the first notes of the **pitch, **MIDI, and **cocho spines have been stripped away (due to the -x option).


The file x_option.awk is used by this program when the -x option is invoked.


DOS 2.0 and up, with the MKS Toolkit. OS/2 with the MKS Toolkit. UNIX systems supporting the Korn shell or Bourne shell command interpreters, and revised awk (1985).


**cbr (2), cbr (4), **cents (2), cents (4), **cocho (2), cocho (4), **freq (2), **fret (2), **kern (2), kern (4), **MIDI (2), midi (4), **pitch (2), pitch (4), **semits (2), semits (4), **solfg (2), solfg (4), **specC (2), specC (4), **Tonh (2), tonh (4)