recip — beat-proportion representation
The recip scheme is able to represent durations according to the traditional system of beat-proportions (rather than according to elapsed- or clock-time.) Durations are specified through the use of integer numbers and augmentation dots. With the exception of the value zero, durations are represented by reciprocal numerical values. For example:
Representations of Duration in recip
The number zero (0) is reserved for the breve duration (i.e. a duration of twice the length of a whole note). Dotted durations are indicated by adding the period character (.) after the numerical value:
|2.||dotted half duration|
|8..||doubly-dotted eighth duration|
Representation of Dotted Durations in recip
Any number of augmentation dots may follow the duration integer.§ § Notice that the period is used both to indicate Humdrum null tokens and recip augmentation dots. In parsing recip spines, there is never any confusion concerning the meaning of the period: as a null token, the period will appear isolated from all other characters (by tabs or carriage returns). As an augmentation dot, the period will always follow a number.
Triplet and other irregular durations are represented in a somewhat more arcane, though no less logical fashion. Consider, for example, the quarter-note triplet duration. Three quarter triplets occur in the time of four quarters or one whole duration. If we divide a whole duration ("1") into three equal parts, each part has a duration of one-third. The corresponding reciprocal integer for 1/3 is 3, hence recip represents a quarter-note triplet as a "third-note" — 3. Similarly, eighth-note triplets are represented by the integer 6 while sixteenth-note triplets are represented by the integer 12. Eighth-note quintuplets (5 in the time of 4) will be represented by the value 10 (a half duration divided by 5).
In general, the way to determine the recip equivalent of an arbitrary "tuplet" duration is to multiply the number of tuplets by the total duration which they occupy. If 7 notes of equal duration occupy the duration of a whole-note ("1"), then each septuplet is represented by the value 7 (i.e. 1 x 7). A more extreme example is 23 notes in the time of a doubly-dotted quarter. The appropriate recip duration can be found by multiplying 4 by 23 (equals 92) and adding the appropriate augmentation dots. Thus "92.." is the correct recip encoding for a note whose duration is 23 notes in the time of a doubly-dotted quarter.
The recip representation can be used to encode a sequence of time-spans or successive durations. The units are inverse time units.
Barlines are represented using the "common system" for barlines — see barlines.
It is recommended that files containing predominantly recip data should be given names with the distinguishing `.rcp' extension.
The following table summarizes the recip mappings of signifiers and signifieds.
|.||dotted duration; null token|
A sample document is given below:
!! Gustav Holst **recip *M5/4 =1 12 12 12 4 4 8 8 4 =2 *-
The following Humdrum command accepts recip encoded data as input:
<span class="tool">timebase</span> reformat <span class="rep">recip</span> score with constant time-base <span class="tool">urrhythm</span> characterize the rhythmic prototype in a passage -- ------------------------------------------- ------------------------------------------------------
The following tandem interpretations can be used in conjunction with recip:
Tandem interpretations for recip
barlines, **date, **metpos, **ordo, **recip, **takt, **time, timebase, **URrhythm, urrhythm, **Zeit