# Command: kern¶

## COMMAND¶

kern – translate selected Humdrum pitch-related representations to **kern

## SYNOPSIS¶

 kern [-x] [inputfile ...] [> outputfile.krn]

## DESCRIPTION¶

The kern command transforms various pitch-related inputs to corresponding **kern representation <../representations/kern.html>__s. For example, the **pitch token Ab2‘ will be output as the **kern token AA-‘. Continuous pitch-related representations, such as frequency (**freq) and cents (**cents) are rounded-off to the nearest equally-tempered pitch. Hence, **freq values between 254.178 and 269.291 will be output as the **kern token for middle C – c’.

Pitches in **kern <../representations/kern.html#Pitch>__ are encoded as equally-tempered values at concert pitch. Kern is not able to represent pitch deviations from equal temperament. Diatonic pitch names are encoded using the letters A to G. Octaves are indicated by a system of upper- and lower-case letters, and by letter repetition. Middle C is represented by the single lower-case letter c’. The C an octave above is represented by two lower-case letters: cc’ – with each successive octave adding another letter. The C an octave below middle C is represented by a single upper-case C’. The C an octave lower yet is represented by two upper-case letters: CC’ – and so forth. Changes of octave are deemed to occur between the pitches B and C. Thus the B below middle c’ is rendered as a single upper-case B’; the B below cc’ is b’ and so forth. Sharps are indicated by the octothorpe sign (#) whereas flats are indicated by the minus sign (-).

The kern 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 **kern) refer to Section 2 (Representation Reference) of this reference manual.

 **cents hundredths of a semitone with respect to middle C=0 **degree scale degree including octave designation **freq frequency in hertz (abbreviated Hz.) **fret fretted-instrument pitch tablature **MIDI Music Instrument Digital Interface key-press tablature **pitch American National Standards Institute pitch notation (e.g. “A#4”) **semits equal-tempered semitones with respect to middle C=0 **solfg French solfège system (fixed doh’) **specC spectral centroid (in hertz) **Tonh German pitch system

Input representations processed by **kern*.*

For numerically-oriented inputs, such as **cents, **freq, **MIDI, **semits, and **specC, variant enharmonic spellings are selected for output according to the prevailing key signature or explicit key indication. (Refer to key and key signatures in Section 3 (Humdrum Tandem Interpretations). Hence, in the key of G minor, F-sharp and E-flat spellings will be output rather than G-flat and D-sharp. Kern recognizes the presence of key, or key signature tandem interpretations. If no key or key signature is encountered in the input, a default key of C major is assumed. Kern is sensitive to both pitch-class and pitch-height key signatures. In the case of pitch-height key signatures, the user can specify complex spelling preferences, such as F#2 rather than Gb2, but Gb3 rather than F#3, etc. See SAMPLE OUTPUT below.

It is recommended that output files produced using the kern command should be given names with the distinguishing .krn’ extension.

## OPTIONS¶

The kern command provides the following options:

 -h displays a help screen summarizing the command syntax -x suppresses printing of non-pitch-related signifiers

Options are specified in the command line.

In the default operation, kern outputs any non-pitch-related signifiers in addition to the kern value. For example, the **pitch token “A6zzz” will result in the output “aaazzz” – that is, after translating A6 to “aaa”, 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 upper- or lower-case letters from A-G. Consider the case of the **freq token “aA#5”; after translating “A#5” to “aa”, the leading non-pitch-related signifier “a” will be prepended to the output, hence the value “aaa” – which will undoubtedly cause confusion. The -x option is useful for eliminating non-pitch-related signifiers from the output. For most inputs, the -x option is recommended.

## SAMPLE OUTPUTS¶

The following example illustrates the use of kern. The input contains six pitch-related spines – two of which (**deg and **cocho) cannot be processed by kern. In addition, there are two non-pitch-related spines (**embell and **metpos). 

!! kern’ example #1 **specC **pitch **MIDI **deg **metpos **cocho **Tonh **embell *M2/4 *M2/4 *M2/4 *M2/4 *M2/4 *M2/4 *M2/4 *M2/4 * * * * *tb8 * * * =1 =1 =1 =1 =1 =1 =1 =1 foo2000 G#4foo /60/bar 1foo 1 r Gis2 ct . . /-60/ . . . . . 2321 A3+20 /62/ 2 3 9.89 H2 upt . . 48/-62/ . . . . . 1807 Ab3 0/70/64 1 2 7.07 B2 ct . . 48/-70/ . . . . . 2487 C#4 /61/ 6 3 7.135 Cis4 sus . . /-61/ . . . . . =2 =2 =2 =2 =2 =2 =2 =2 3323 r . 5 1 r r . . . . 7 3 5.5 Heses2 ct 3471 D4-8 /48/ /52/ 1 2 8.11 C3 ct . . /-48/ . . . . . . D4 F4 /-52/ 2 3 7.33 6.4 C3 Es3 ct =3 =3 =3 =3 =3 =3 =3 =3 r G4 . r 1 r H2 D3 . === === === === === === === === *- *- *- *- *- *- *- *-

Executing the command

 kern -x input > output.krn

produces the following result: 

!! kern’ example #1 **kern **kern **kern **deg **metpos **cocho **kern **embell *M2/4 *M2/4 *M2/4 *M2/4 *M2/4 *M2/4 *M2/4 *M2/4 * * * * *tb8 * * * =1 =1 =1 =1 =1 =1 =1 =1 bbb g# c 1foo 1 r GG# ct . . . . . . . . dddd A d 2 3 9.89 BB upt . . . . . . . . aaa A- b- 1 2 7.07 BB- ct . . . . . . . . eeee- c# d- 6 3 7.135 c# sus . . . . . . . . =2 =2 =2 =2 =2 =2 =2 =2 aaaa- r . 5 1 r r . . . . 7 3 5.5 BB– ct aaaa d C E 1 2 8.11 C ct . . . . . . . . . d f . 2 3 7.33 6.4 C E- ct =3 =3 =3 =3 =3 =3 =3 =3 r g . r 1 r BB D . === === === === === === === === *- *- *- *- *- *- *- *-

Both processed and unprocessed spines are output. Also notice that the non-pitch-related signifiers (e.g. foo) in the first notes of the **specC, **pitch, and **MIDI, spines have been stripped away (due to the -x option).

Key signature sensitivity is illustrated in the following example. The input contains a “pitch-height key signature” – where flats and sharps pertain to only a specific absolute pitch. For example, Bb3 is preferred to A#3, although A#4 is preferred to Bb4. Similarly, C#4 is preferred to Db4, although Db5 is preferred to C#5. 

 !! kern’ example #2 **semits *K[B3-C4#F4#A4#D5-] -2 10 1 6 13 *-

Notice in the corresponding output given below, that all pitches are rendered with the correct enharmonic spelling. 

 !! kern’ example #2 **kern *K[B3-C4#F4#A4#D5-] B- a# c# f# dd- *-

## FILES¶

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

## PORTABILITY¶

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).

 **cents (2), cents (4), **degree (2), degree (4), **freq (2), freq (4), **fret (2), hint (4), **kern (2), mint (4), **MIDI (2), midi (4), **pitch (2), pitch (4), proof (4), **semits (2), semits (4), **solfg (2), solfg (4), **specC (2), specc (4), **Tonh (2), tonh (4)
When translating **pitch, **solfg, or **Tonh, inputs, kern ignores cents deviation. Hence C#6+80 is rendered as ccc#’ rather than the nearest pitch ddd’.
Humdrum representations are expected to avoid context dependency insofar as possible. This can lead to unexpected results. For example, the letter x’ in **pitch is intended to signify the presence of a double sharp. Thus the **pitch input token xyzC4’ is correctly translated by kern as yzc##’. Similarly, the **pitch input token 1yzC4’ becomes yzCCC4’. (The first numerical value is interpreted as the octave number and the trailing number 4 is interpreted as a non-pitch-related signifier.)