How we count
Sheetly reads 118 distinct printed notation marks: every clef, key signature and meter, note and rest values from a breve to a 128th, all five accidentals, repeat barlines and endings, the D.C., D.S., segno and coda family, ties, tuplets, the common articulations and ornaments, dynamics and expression marks on single-line parts, and drum notation. The count is conservative: a dotted quarter and a plain quarter count once each, not once per pitch, per octave or per key.
- A mark counts once, no matter how many pitches, octaves or keys it can appear on. A sharp is one mark, not thirty-five.
- Combinations do not count. A staccato under a slur is two marks, not a third.
- If a family is open-ended (any number over a barline count, any multi-rest length), it counts once.
- What Sheetly cannot read is listed too, in the same detail. That section is further down.
One more distinction worth keeping: coverage is not accuracy. This page says what the scanner can read; the open benchmark says how often it reads it correctly: 96% strict note F1 on clean scores, 95% on phone photographs, with the test pages and scorer downloadable. A symbol list without an accuracy figure is a brochure; the two together are a specification.
Clefs: 10
Sheetly reads the treble (G) clef on lines 1 and 2, the bass (F) clef on lines 3, 4 and 5, and the C clef on all five lines, which covers alto and tenor clef for viola, trombone, bassoon and cello parts. That is ten distinct clef positions. A printed clef is also verified after decoding: the glyph at the left edge of each staff is template-matched against what the reader decoded, so a treble clef misread as alto, which would shift every note in the system, gets caught and corrected.
- G clefs (2): treble clef, French violin clef
- F clefs (3): bass clef, baritone clef, sub-bass clef
- C clefs (5): soprano, mezzo-soprano, alto, tenor, baritone
Key signatures: 15
All of them: C major/A minor with no marks, the seven sharp keys from one sharp (G) to seven (C♯), and the seven flat keys from one flat (F) to seven (C♭). Key changes mid-piece are read wherever a new signature is printed. Which sharps and flats apply, and how to name the key, is its own guide: how to read key signatures.
Time signatures: 12 forms
Numeric meters with denominators 1, 2, 3, 4, 6, 8, 12, 16, 32 and 48, plus the two symbol forms, common time (C) and cut time (¢). That covers everything from 2/2 and 3/4 to 6/8, 12/8 and the odd meters. The printed meter of the first system is additionally read by a separate deterministic check straight off the page image, so a misread 3/4-versus-6/8 gets a second opinion. Meter changes mid-piece are read where printed, and a pickup bar shorter than the meter is kept as a pickup rather than padded out.
Notes and durations: 13 marks
Ten duration values: long, breve, whole, half, quarter, eighth, sixteenth, thirty-second, sixty-fourth and hundred-twenty-eighth notes. On top of those, the augmentation dot, the double dot, and grace notes. Chords, two or more noteheads sharing a stem, are read as chords, and a staff carrying two independent voices (the usual case in hymn books and much piano writing) keeps both voices separate. Pitch is read across the full range a page can print, ledger lines included; if you are shaky on those, see how to read ledger lines.
Rests: 11 marks
The same ten duration values as notes, whole rest to 128th rest, dotted where printed, plus the multi-measure rest, the H-bar with a count over it that condenses many silent bars into one. Multi-rests get particular care because band and orchestra parts live on them: the bar and its printed count are located geometrically on the page image, so a “12 bars of rest” sign expands to exactly twelve bars in the score, in the right place. In the player, a condensed rest bar is swept once per counted bar with a “k / N” counter so you always know where you are.
Accidentals: 5
Sharp, flat, natural, double sharp, double flat. Read per note where printed, on top of whatever the key signature already applies.
Barlines and repeats: 6
The single barline, the double barline, and the final (thin-thick) barline; then the repeat family: start repeat, end repeat, and the back-to-back end-start. Repeat dots are the classic scanner failure (small, easily lost in a dense system), so they get a dedicated second reader: the two dots beside a doubled barline are detected geometrically, anchored to the printed staff grid, and merged with what the main reader found. A repeat sign is either on the page or it is not. Nothing is inferred from context.
Ties, slurs and tuplets: 3
Slurs are read as printed. Ties deserve an honest note: the reader itself emits every curved line as a slur, and a deterministic pass then promotes the tie-shaped ones, those at the same pitch and adjacent in time, into real ties, so a held note sounds held instead of restruck. A tie survives only when both endpoints exist and the pitches match; a broken candidate is dropped rather than guessed. Tuplets are read with their ratios, triplets first among them but irregular groups too; if triplets are new to you, start with how to read triplets.
Articulation and ornaments: 10
- Articulation (5): staccato, staccatissimo, accent, tenuto, fermata
- Ornaments and effects (5): trill, turn, tremolo, arpeggio, breath mark
These are read singly and in the printed combinations, such as an accented staccato or a fermata over a trill, without the combinations inflating the count.
Dynamics and expression: 18
On a single-line part, one instrument on one staff such as a band part or a solo line, Sheetly reads the loudness and expression marks, and playback follows the dynamics: a p plays soft until the next dynamic, and an sfz lands on its note. Piano music and scores with several parts are not read for these marks yet. Every mark is checked against a fixed list, and one it is unsure of is left out rather than guessed.
- Dynamics (14): ppp, pp, p, mp, mf, f, ff, fff, sf, sfz, fz, rfz, fp, sfp
- Hairpins (2): crescendo and diminuendo
- Rehearsal marks (1): the boxed letters and numbers a band uses to say “from letter B”
- Expression and tempo words (1): cresc., dim., rit., rall., accel., a tempo, dolce, Solo, Tutti and the other common ones, counted once as a family
Drum notation: 2
Drum parts are read on a five-line staff, or a one-line staff for claps and single instruments. Each hit is mapped to its drum by where it sits on the staff, and the part plays back on a drum kit.
- Percussion clef (1)
- X noteheads (1): hi-hat, cymbals and the other x-headed hits
Layout it understands
Not symbols, so not counted, but part of reading a page: the grand staff (two staves braced together, as in piano music), multi-staff systems with several instruments, systems of unequal width, pickup bars, key and meter changes mid-piece, and the title and composer printed at the top, which are read and attached to the score. A printed metronome mark is used for the starting tempo when it is legible; otherwise the tempo is estimated from the music and marked as estimated, never passed off as printed.
What Sheetly cannot read yet
A coverage page that only lists hits is a brochure. These are the misses, in the same detail.
- Dynamics on piano music and full scores. On a single-line part they are read (above); on a grand staff or a score with several parts, not yet.
- Lyrics. Notes of a vocal line yes; the words under them, no.
- Octave lines. 8va and 8vb passages are played at written pitch.
- Chord symbols and fretboard diagrams. The letter names and grids above the staff in lead sheets are not read.
- Fingering numbers and pedal marks. Not read.
- Glissando lines. Not read.
- Handwritten manuscript. Sheetly reads printed and engraved notation; handwriting is out of scope, and here is the honest page about that.
- Guitar tablature. Not read.
When a page contains one of these, the mark is skipped and everything around it is read normally. The rule across the whole reader is the same: read it from the page or leave it out, never invent it. If a mark you care about is missing from the wrong list, tell us at hello@trysheetly.com; this page changes when the reader does.
The arithmetic
- Clefs: 10
- Key signatures: 15
- Time signatures: 12
- Note durations, dots and grace notes: 13
- Rests and the multi-measure rest: 11
- Accidentals: 5
- Barlines and repeat barlines: 6
- Ending brackets: 3
- Navigation marks: 8
- One-bar repeat (simile): 1
- Ties, slurs, tuplets: 3
- Articulation: 5
- Ornaments and effects: 5
- Chords: 1
- Dynamics: 14
- Hairpins: 2
- Rehearsal marks: 1
- Expression and tempo words: 1
- Percussion clef: 1
- X noteheads: 1
10 + 15 + 12 + 13 + 11 + 5 + 6 + 3 + 8 + 1 + 3 + 5 + 5 + 1 + 14 + 2 + 1 + 1 + 1 + 1 = 118. Count it per dotted variant, per key or per octave, and you can advertise a much bigger number from the same reader. We would rather publish the small number and the rule than the big number and no rule.
Questions
How many music symbols can Sheetly read?
118 distinct printed marks, counted conservatively: 10 clef positions, all 15 key signatures, 12 meter forms including common and cut time, 10 note durations plus dots and grace notes, 10 rest durations plus multi-measure rests, all 5 accidentals, 6 barline forms including repeats, 3 ending brackets, 8 navigation marks (segno, coda, D.C. and D.S. forms), the one-bar repeat sign, ties, slurs, tuplets, 5 articulations, 5 ornaments, chords, 14 dynamics, 2 hairpins, rehearsal marks, expression words, the percussion clef and x noteheads. A dotted note and its plain twin count once each, not once per pitch or per meter. The arithmetic is on this page.
Does Sheetly read dynamics like p, f and hairpins?
Yes, on single-line parts. Sheetly reads 14 dynamics from ppp to fff, including sfz and fp, plus crescendo and diminuendo hairpins, and playback follows the dynamics. On piano music and scores with several parts they are not read yet.
Does Sheetly read repeat signs, first and second endings, and D.S. al Coda?
Yes. Repeat barlines, first and second ending brackets, segno, coda, To Coda, Fine, and the D.C. and D.S. instructions are all detected and written into the score. The dots, brackets and glyphs are found by deterministic computer vision anchored to the printed staff geometry rather than guessed by a language model, so a repeat sign is either found on the page or absent, never invented.
Does Sheetly read lyrics?
No. On a vocal or choir part Sheetly reads the notes, rhythms and structure of the music, and the words underneath are not transcribed. The title and composer printed at the top of the page are read and attached to the score.
What happens when a page contains a mark Sheetly cannot read?
It is left out rather than guessed at. An unreadable ornament or a dynamic marking does not disturb the notes around it: the pitches and rhythms are transcribed, the unknown mark is skipped, and playback continues as written. Sheetly’s design rule is that a mark is either read from the page or absent from the score. Nothing is invented to fill a gap.
How does symbol coverage relate to the accuracy benchmark?
Coverage says what Sheetly can read; the benchmark says how often it reads it correctly. The two are published separately on purpose: this page lists the 118 marks in the reading vocabulary, and the open benchmark measures 96% strict note F1 on clean scores and 95% on phone photographs, with the test pages, ground truth and scorer downloadable so anyone can recompute the figures.