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).


SEE ALSO

`` **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)``


BUGS

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’.


WARNINGS

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.)