Alto Trombone Position Annotator

Slide positions, printed under every note — for tenor trombone sheet music played on an E♭ alto.

Sheet music

One image per page (PNG or JPG), selected in page order. Scans work best; phone photos have tilt and page curvature corrected automatically, but keep the page as flat and evenly lit as you can.

Methods — pick one or more; each gets its own PDF and MIDI files, inked in the card's colour

Octave upSame key, sounds one octave above written. The usual choice. Written pitchPlay exactly what is written, standard alto positions. Up a fourthRead with tenor positions; sounds a perfect fourth higher.

Key signature — read from the image; pick a key only to override

Major key Numbers go

Advanced settings

Ledger range Sensitivity Skip left (staff spaces)

Ignore printed accidentals (key signature only)

Skip page-curvature correction (photos)

Preparing the Python runtime. The first visit downloads about 60–90 MB; later visits use the cache.

Progress log

The ▶ buttons play each MIDI rendering right here in the page. The downloaded .mid files need a synthesizer app such as GarageBand, MuseScore or a DAW — QuickTime and VLC on macOS cannot play MIDI files, even though the files are fine. Everything runs in your browser — images never leave this device — and the progress log above streams while pages are processed. In the results, a green/blue/red number is a confident reading, * marks a note read via a detected accidental, and an orange number is a best guess — verify it by eye. A detected note with no number printed has no slide position in the chosen method (it appears as ? in the log); the space is left blank so you can pencil it in. When the key is auto-detected, the log shows a detected key line per page — if it disagrees with the printed signature, pick the key manually and run again.