MIDI TUNING STANDARD

In music, the 'MIDI Tuning Standard', or MTS, is a specification of musical pitch agreed to by the MIDI Manufacturers Association. It allows for both a bulk tuning dump message, giving a tuning for each of 128 notes, and an individual tuning message.
If f is a frequency in hertz, then we may compute a corresponding logarithmic frequency value by
:$d\; =\; 69\; +\; 12\; cdot\; log\_2(f/440).$
Since 440 Hz is the standard concert A, and since that is represented in MIDI terms by the integer 69 (nine semitones above middle C, which is 60), this gives a real number which expresses pitch in a manner consistent with MIDI and integer notation. These numerical units do not seem to have a recognized name, though it has been called the ''dollar'' in analogy to cents. While "dollars" and cents do not represent the same thing, since the former is a logarithmic measure of frequency and the latter a logarithmic measure of frequency ratios, a difference of one dollar equals one hundred cents. Given this "dollar" value, we can convert back to frequency by
:$f\; =\; 440\; cdot\; 2^\{(d-69)/12\}$
so that the two notations are equivalent.
The pitch values of MTS can be briefly described as dollar values, converted into three digits of base 128. These are byte-sized digits, represented in hexadecimal notation by 00 through 7F, which is to say, from 0 to 127 in base 10. The first byte digit represents the MIDI note, or integer notation, value. The next two digits allow the semitone to be divided into
128² = 2¹⁴ = 16384 parts, which means the octave is divided into 196608 equal parts. These parts are 100/16384 = 0.0061 cents in size, which is far below the threshold of human pitch perception and which therefore allows a very accurate representation of pitch.

Contents

Programs supporting MTS

See also

External links

MTS specification

Microtonal music software supporting MTS

Programs supporting MTS

Most software making use of MIDI does not support, or at least fully support, MTS. In particular there is a notable lack of MIDI players which play files using it. Software which does support the MIDI tuning standard includes
Scala, TiMidity, L'il Miss Scale Oven, Max Magic Microtuner, and the Native Instruments FM7 softsynth.

See also

★ Microtonal music

★ Microtuner

★ Musical tuning

External links

MTS specification

★ MTS specification

★ Detailed MTS specification

★ MTS extensions

Microtonal music software supporting MTS

★ L'il Miss' Scale Oven (Mac)

★ Scala (Windows, Linux, Mac)

★ TiMidity++ (Windows, Linux, Mac)