Scope

As played by is an MEI customization. It defines how an MEI document carries, beside the score, a record of one or more performances of it: which written note a sounded event realised, when it was struck, how long and how loud. The record lives in performance, and nothing outside it is constrained.

Two applications currently make use of this customization, the MPM Desk and the verovio fork on branch aligned-mei, which lays a score out along performed time rather than notated duration.

Performance information is encoded in the when element.

What is added

recording is not a member of att.source in MEI 5.1, so it cannot name the take it records. Both readers rely on that name: it is how a document holding several takes says which one a given when belongs to, and how the verovio option performanceRecording selects one. The alternative would be avFile, which names a file rather than the manifestation the header already describes.

Whether this is the right way round is an open question. Asking the MEI community to put recording into att.source would remove the need for a customization at this point altogether.

What is narrowed

A when in a recording takes one of five shapes, told apart by type and by which of data and absolute are present. A match has both, because there is a written note and a moment it sounded at. A deletion has only data, because the note was never played. An insertion has only absolute, because something sounded that the score does not write. A substitution has both and sounds at a pitch the score does not give. A pedal event has only a moment.

absolute is restricted to whole milliseconds written with the ms unit. The same holds for extData of type duration.

A pedal event may carry the pedal's travel over the press in an extData of type travel: pairs of a time in whole milliseconds, counted from absolute, and a position from 0, the pedal up, to 1, the pedal fully down, ascending in time. Where a pedal event carries its travel, absolute is the moment the pedal left rest and duration runs until it returned there; a reader that wants a switch takes the crossings of one half. Where it does not, the record is the switch, and absolute is the moment the pedal was pressed. The travel need not hold every sample the source had. A vertex wherever the position moved by more than a reader would draw, and both ends of every stretch at one position, are enough to redraw the line. The modelled bellows of a reproducing piano arrive this way, with the relay's delay and the traversal in the line rather than thresholded away.

The type of an extData is drawn from a closed list.

Constraining type on when also constrains the when elements inside a clip, which this format does not otherwise use. A document that needs clip for its own purposes is outside the scope of this customization.

Known pitfalls

performance is a member of model.resourceLike, which music admits only before front and body. Appending it to music puts it after body, where MEI does not allow it.

References Devaney, Johanna, and Hubert Léveillé Gauvin. . 20 (2019), 81–91. https://doi.org/10.1007/s00799-017-0229-3 Neumann, Joshua, and Kristina Richts-Matthaei. . , 2024. https://works.hcommons.org/records/mb7px-jtd86

Schema One performance of the score, named by the manifestation it was taken from. A recording must name its take in @source, so that a document holding several takes can say which one a when belongs to. The @source of a recording must be a reference of the form '#id' resolving to an element of this document, usually a manifestation. Two recordings carry the same @source, so neither can be selected by it. A match names the written note in @data. A match names the moment it sounded in @absolute. A deletion names the written note in @data. A deletion has no @absolute, because the note was never played. An insertion has no @data, because there is no written note for it to point at. An insertion names the moment it sounded in @absolute. An insertion carries the pitch that sounded in extData of type 'pitch', since the score does not give it. A substitution names the written note in @data. A substitution names the moment it sounded in @absolute. A substitution carries the pitch that sounded in extData of type 'pitch', which is what makes it a substitution rather than a match. A pedal event has no @data, because it realises no written note. A pedal event names in @absolute the moment it was pressed, or, where it carries its travel, the moment it left rest. The @data of a when must be a reference of the form '#id' resolving to an element of this document. The @absolute of a when is written in whole milliseconds with the 'ms' unit. Other forms MEI allows are read differently by the two readers this format serves. A when carrying @absolute states @abstype='smil'; the verovio fork warns on any other value. An ornamentAnchorConfidence is written together with an ornamentAnchorConfidenceOf naming which quantity it holds. An unlabelled number cannot be compared across files. The ornament fields describe an anchor, so they require an ornamentAnchor to describe. Which of the five shapes this record takes. A written note that sounded. A written note that was not played. A note that sounded without being written. A written note that sounded at another pitch. A press of the sustaining pedal. A press of the soft pedal. A velocity or a pitch is a whole number from 0 to 127. A duration is written in whole milliseconds with the 'ms' unit, for the reason given for @absolute. A tick count and an ornament slot are whole numbers. A confidence is a number from 0 to 1. An ornamentAnchor is a reference of the form '#id' resolving to an element of this document. A travel belongs to a pedal event; a note has none. A travel is a list of pairs 'ms:position' separated by whitespace: the milliseconds whole and counted from @absolute, the position from 0 (up) to 1 (down). The pairs of a travel ascend in time. An ornamentAnchorFrom says whether the model named the anchor ('model'), whether an ornament sign in the score settled a ranking the model was unsure of ('model-and-sign'), or whether it was guessed from the timing ('timing'). Which measurement or judgement this datum holds. MIDI velocity, 0 to 127. How long the note sounded, in whole milliseconds. The MIDI pitch that sounded. The MIDI pitch the score writes, where another sounded. The onset in the ticks of the source recording. The duration in the ticks of the source recording. A pedal's travel over the press: pairs of milliseconds since @absolute and position from 0 (up) to 1 (down), ascending in time. How sure the aligner was of this record, from 0 to 1. What a reader made of the divergence. Who is responsible for that reading. How sure that reader was. The written note this sounded note decorates. How the anchor was arrived at. How sure the anchor is, from 0 to 1. Which quantity that confidence holds. Where this note falls within its ornament. An as-played-by document records at least one performance, so its music holds a performance with a recording in it.