Show HN: Claude Plays the Piano from Braille

A developer released a Show HN project that decodes Hu Haipeng's North American ASCII music braille transcription of Nicolás Ruiz Espadero's 1874 piano transcription of Gottschalk's Grande Tarantelle (IMSLP #933069, CC BY-SA 4.0) into a full expressive MIDI and audio performance. The Python decoder, brf.py, reads the braille into timed notes and handles octave marks, in-accord, repeats, triplets and quintuplets, grace notes and key changes across all 539 bars, with six places corrected against the Ditson print (IMSLP #07731), including a left-hand A major chord in bars 2, 3, 5, 440, 444 and 446 and a stray '5k' in bar 489. perform.py layers tempo at dotted-quarter = 158, rubato, dynamics and pedal, and render.swift plays the MIDI through the macOS sampler offline into an .m4a, since AVAudioUnitSampler cannot load GarageBand's EXS24 Steinway instrument (error -10868).

gottschalk-tarantelle-espadero.mp4 An expressive MIDI performance, decoded from the braille transcription of the score. The piece is Nicolás Ruiz Espadero's transcription for piano alone, Boston: Oliver Ditson, 1874. | File | What it is | |---|---| | espadero.brf | The score in North American ASCII music braille, bar-over-bar: Hu Haipeng's transcription for the Braille Orchestra and Open Braille Music projects IMSLP 933069 https://imslp.org/wiki/Grande Tarantelle%2C Op.67 %28Gottschalk%2C Louis Moreau%29 , CC BY-SA 4.0 | | brf.py | Reads the braille into timed notes the subset of the BANA Music Braille Code the file uses ; prints the decoded notes bar by bar | | perform.py | Turns the notes into the performance: tempo, rubato, dynamics, voicing, articulation, pedal | | render.swift | Plays a MIDI file through the macOS sampler, offline, into an .m4a | | gottschalk-tarantelle-espadero.mid | The performance | | gottschalk-tarantelle-espadero.m4a | The performance as audio | | LICENSE-MIT | The MIT license, for the code | | LICENSE-CC-BY-SA-4.0 | Creative Commons Attribution-ShareAlike 4.0 International, for the braille, the performances and the rest | The Python needs only the standard library 3.11 or later ; render.swift needs macOS and Swift the Xcode command-line tools . python3 perform.py espadero.brf -o gottschalk-tarantelle-espadero.mid swift render.swift gottschalk-tarantelle-espadero.mid gottschalk-tarantelle-espadero.m4a python3 brf.py espadero.brf 1 12 the decoded notes of bars 1-12 perform.py --report prints the tempo, loudness and markings of every bar; --tempo sets the dotted-quarter tempo 158 , --no-repeats skips the two repeats. For a better piano, open the .mid in GarageBand: File › Open , or drag it into an empty project. When GarageBand asks Also import tempo information? , click Import Tempo : the rubato lives in the tempo map, and without it the piece plays metronomically. If the track does not come up as a piano, pick Piano › Steinway Grand Piano in the Library. Bars and key changes line up with the score, so it reads correctly in a DAW or notation program too. render.swift cannot use GarageBand's Steinway itself: it is an EXS24 instrument over one consolidated .caf , which AVAudioUnitSampler will not load error -10868 . The braille gives every pitch and duration exactly, so no optical reading of the 1874 scan was needed. The decoder handles the code as this file uses it: octave marks and BANA's rules for unmarked octaves, intervals read down in the right hand and up in the left, interval doubling -- , full- and part-measure in-accord, measure and part-measure repeats whose extent comes from the bar's length , 16th-note grouping, triplets and quintuplets, stem signs, grace and cue-size notes, cautionary accidentals in parentheses in print, ,' … ,' in the braille , ties, slurs, fingered tremolos, hand changes within a line, first and second endings, and key changes. Every voice of all 539 bars and the two second endings adds up to exactly 6/8. Bars were compared with the Ditson print IMSLP 07731 in every section. Six places in the braille differ from the print and are corrected in brf.py CORRECTIONS : | Bars | Braille | | |---|---|---| | 2, 3, 5, 440, 444, 446 | Left-hand A major chord as A2 C♯3 E3 | A2 E3 C♯4 the tenth needs an octave mark the braille lacks | | 489 | A stray 5k after the third note | Nothing; without it the bar is exactly 6/8 | The braille leaves out the print's ossia and Facilité staves, so they are not played. The cue-size notes the score marks avec les petites notes ad lib. bars 309–322 are played, softly. Everything beyond the notes is an interpretation layered over the score's own markings: - Tempo : Tempo di Tarantella at ♩. = 158, with a light lilt on each beat. Each four-bar phrase presses forward a little and eases at its cadence. The music broadens into double bars and key changes and takes a breath after them. animando presses about 7% into its climax, rides it, then settles. dolce and pesante are a shade slower. Più mosso bar 498 is about 11% faster to the end. Fermatas are held about twice their length, and the last line is broad. - Dynamics : the printed levels, fp , sf / rfz , cresc. / dim. ramping to the next printed level and hairpins as swells . Where the print gives none, the orchestral Tutti enters at least f , and an unmarked Solo after it steps down to f . On top of that, the melody grows as it rises above its surroundings, beat 1 of each bar and beat 2, less is stressed, and eight-bar arcs give it shape. legg. , scherz. and scintillante are lighter; martellato , pesante and con impeto heavier. - Voicing : the top of each right-hand chord is louder, inner notes recede, and the bass is firm. - Chords : no chord lands all at once. Each hand places its chord separately, the left hand usually a few milliseconds ahead. Within a hand the notes fan out, mostly from the bottom up, over about 10 ms for an octave to 20–40 ms for a big chord, wider the more notes and the wider the stretch. The melody note leads in the right hand and the bass in the left. A chord never fans out over more than a third of the time to that hand's next one, so fast repeated chords stay crisp. Printed arpeggios roll from the bottom at about 30 ms a note. - Touch : staccato and staccatissimo are short, slurs and held stems legato, accents, marcato and tenuto as printed, and unmarked notes slightly detached. - Pedal : as the braille marks it, each Ped. lifting and catching again just after the beat. - Ornaments : grace notes come just before the beat, and the final D1–D2 tremolo is played out in sixteenths. - Variation : the timing wanders slowly by a few milliseconds, and velocities and releases vary a little from note to note. The randomness is seeded, so every build is the same. - Repeats : both are taken bars 141–172 and 391–422 , with their first and second endings: 603 bars, about 7½ minutes. The code brf.py , perform.py , render.swift is under the MIT license https://github.com/chris-mccoy/gottschalk-tarantelle/blob/main/LICENSE-MIT . The braille transcription in espadero.brf is by Hu Haipeng, for the Braille Orchestra and Open Braille Music projects brailleorch.org http://www.brailleorch.org , published on IMSLP https://imslp.org/wiki/Grande Tarantelle%2C Op.67 %28Gottschalk%2C Louis Moreau%29 933069 under the Creative Commons Attribution-ShareAlike 4.0 license. The MIDI and audio performances are adaptations of it, and they and the rest of the repository this README included are shared under the same license: CC BY-SA 4.0 https://github.com/chris-mccoy/gottschalk-tarantelle/blob/main/LICENSE-CC-BY-SA-4.0 . The Ditson print of 1874 that the transcription follows, and Gottschalk's and Espadero's music, are in the public domain.