# Handel *Dixit Dominus* HWV 232 — répétiteur / piano rendering architecture ## Canonical accompaniment rendering workflow v1 FINAL **Status:** canonical production method **Date:** 8 Oct 2026 **Scope:** canonical accompaniment method through Movement 8 FINAL **Companion canonical documents:** ```text DIXIT_REHEARSAL_METHODS_canonical_through_mvt8_FINAL.md DIXIT_MODULAR_PLAYER_ARCHITECTURE_v1_FINAL_updated_through_mvt8_FINAL.md ``` This document is authoritative for the **accompaniment construction and piano-rendering layer** of the project. Its purpose is to prevent three distinct decisions from becoming conflated: ```text what Handel wrote ↓ what the rehearsal piano should play ↓ what piano timbre renders that accepted MIDI ``` The first two are musical/structural decisions. The third is a rendering decision. A change in piano sound must not silently change the accepted notes, rhythms, ties, voicing, or reduction logic. --- ## 1. Canonical layered model Use this separation: ```text literal instrumental score extraction ↓ instrumental QC / tie / tuplet validation ↓ accepted rehearsal reduction MIDI ↓ canonical piano rendering chain ↓ canonical WAV master ↓ web MP3 ↓ hidden player calibration ``` Each layer should be independently reproducible. Do not collapse the pipeline into "generate a piano WAV". --- ## 2. Decide the accompaniment strategy from the written texture Two accompaniment cases are now established. ### A. Sparse continuo texture If the score supplies essentially: ```text solo voice + continuo / figured bass ``` the rehearsal accompaniment may require a cautious harmonic realisation. Movement 2 — *Virgam virtutis tuae* — is the canonical example. The realisation should remain subordinate to the written bass and figures. Do not invent gratuitous pianistic activity. ### B. Fully written orchestral texture If Handel has already written enough independent upper voices to define the harmony, reduce those written voices directly. Movement 3 — *Tecum principium* — is the canonical example: ```text RH / upper texture: Violin I Violin II Viola I Viola II LH / bass: continuo ``` General rule: > Fully written harmony should be reduced before harmony is invented. The répétiteur is a rehearsal representation of Handel's written texture, not an attempt to reproduce an unrelated published piano reduction. --- ## 3. Literal instrumental extraction must close before reduction Do not repair parser errors inside the reduction layer. For every instrumental staff: - parse literal pitches; - parse literal durations; - parse active clef; - parse accidentals; - identify ties; - identify rests; - identify candidate tuplets; - validate every measure against the active metre. Proceed to reduction only when there are **zero unexplained bar-closure errors**. Movement 3 final instrumental extraction: ```text Violin I 403 events Violin II 257 events Viola I 190 events Viola II 194 events Continuo 244 events confirmed instrumental ties: 12 unexplained bar-closure errors: 0 ``` This is the model standard. --- ## 4. Tuplets: engraving topology proposes; metre validates Do not classify every three-note beam group as a triplet. Canonical inference: 1. use common physical beam-group identity to identify a triplet candidate; 2. evaluate that interpretation against exact measure closure; 3. choose the smallest necessary set of tuplet interpretations that closes the bar correctly; 4. preserve ordinary quavers where straight duration already closes the metre. Movement 3 continuo bar 35 is the regression case: ```text dotted crotchet + three ordinary beamed quavers = exactly one 3/4 bar ``` Those three quavers are **not** a triplet. --- ## 5. Ties are structural, not cosmetic Confirmed ties must survive into the accompaniment MIDI. Canonical MIDI behaviour: ```text tie source -> note-on tie destination -> NO new note-on final tie note -> note-off ``` Do not re-articulate a tied bass or upper voice merely because a new bar begins. ### Harmonic reattack rule Movement 2 exposed a subtler failure: A tied bass was correctly sustained, but the generated RH chord was re-struck at the tie destination, making the whole piano texture sound as though the bass had been attacked again. Canonical rule: > If an RH attack occurs exactly on a confirmed bass-tie destination, repeats > the existing voicing, and there is no new harmonic/figured-bass instruction, > sustain the existing texture rather than re-striking it. If harmony genuinely changes over the tied bass, the upper texture may move. Tie QC must therefore inspect the **whole accompaniment texture**, not just the literal bass MIDI events. --- ## 6. The accepted MIDI is the musical master of the accompaniment Once the reduction has passed listening QC, freeze the MIDI independently from its rendered piano sound. For Movement 3: ```text accepted musical reduction: dixit_mvt3_repetiteur_piano_v1.mid ``` When the piano timbre was later found to differ from Movements 1 and 2, the correct repair was: ```text reuse accepted v1 MIDI unchanged ↓ rerender through canonical piano chain ``` Do **not** regenerate the reduction merely to change timbre. Core rule: > Notes/timing and instrument rendering are separate versioned layers. --- ## 7. Canonical piano rendering chain The accepted common piano timbre for the project is: ```text renderer: FluidSynth SoundFont: /usr/share/sounds/sf2/FluidR3_GM.sf2 instrument: FluidR3 General MIDI Acoustic Grand Piano FluidSynth gain: -g 0.6 sample rate: 44100 Hz ``` Canonical command pattern: ```bash fluidsynth -ni -g 0.6 \ /usr/share/sounds/sf2/FluidR3_GM.sf2 \ INPUT.mid \ -F OUTPUT.wav \ -r 44100 ``` This rendering family was established in Movement 1 and retained for the accepted Movement-2 répétiteur. Movement 3 was initially rendered with a different piano sound; it was later rerendered from the accepted v1 MIDI through this FluidSynth/FluidR3 chain and accepted as matching the earlier movements. Therefore: > FluidSynth + FluidR3_GM.sf2 is the canonical répétiteur piano renderer unless > a future project-wide change is explicitly evaluated and accepted. Do not silently fall back to another installed SoundFont merely because it is available. --- ## 8. Canonical WAV versus web encoding The canonical accompaniment render should first exist as an uncompressed WAV. Movement-3 matched-timbre render: ```text /home/ajp/dixit/mvt3/ dixit_mvt3_repetiteur_piano_v2_FluidR3.wav ``` The web player should use a derived MP3. Typical project web encoding: ```bash ffmpeg -i INPUT.wav \ -ac 1 \ -ar 32000 \ -codec:a libmp3lame \ -b:a 96k \ OUTPUT.mp3 ``` A higher-bitrate audition MP3 may also be produced, e.g. 160 kb/s. Never treat the web MP3 as the canonical musical master. Hierarchy: ```text accepted MIDI + canonical WAV > web MP3 ``` --- ## 9. Do not bake player balance into the master audio Raw piano render level and rehearsal-player balance are separate concerns. The canonical WAV should not be destructively amplified or normalised merely to make a particular web-player slider position convenient. Instead: ```text raw rendered level ↓ hidden per-stem calibration ↓ visible mixer percentage ``` The visible mixer defaults to 70%. The hidden calibration compensates for differences between renderers, voicebanks, and accompaniment masters. --- ## 10. Recalculate calibration after a timbre/render change A new piano render can differ dramatically in raw level even when it represents the same MIDI. Therefore a timbre rerender invalidates the previous hidden calibration. Movement 3 is the canonical example. Original Movement-3 piano render: ```text required hidden piano calibration ≈ 9.0 ``` That unusually high factor reflected the quiet raw render, not a musical desire for ninefold piano emphasis. After rerendering through the canonical FluidR3 chain: 1. compare the raw new piano level with an accepted reference piano; 2. account for the movement's master gain; 3. derive a new starting hidden calibration; 4. audition musically; 5. freeze only after listening. A calibration value belongs to: ```text specific audio render + specific player gain structure ``` It does not belong permanently to "Movement 3 piano". --- ## 11. Reference-based starting calibration Movement 2 is a useful accepted reference because its final piano is already part of the common FluidR3 family. Accepted Movement-2 player values: ```text Piano hidden calibration = 3.59 master gain = 0.58 ``` A useful starting estimate for a newly rerendered Movement-3 piano is: ```text new_calibration ≈ reference_calibration × (reference_master / target_master) × linear RMS-level ratio ``` where: ```text linear RMS-level ratio = 10 ^ ((reference_dB - target_dB) / 20) ``` This is a **starting point**, not an automatic musical truth. Final calibration still requires comparative listening. --- ## 12. MIDI instrument/program discipline The accompaniment MIDI should use an acoustic piano program compatible with the canonical SoundFont. If a builder creates a dedicated piano reduction MIDI, ensure its program change is explicit rather than relying on whatever program the synthesizer happens to default to. For General MIDI, Acoustic Grand Piano is program 1 in human-facing numbering (program value 0 in zero-based MIDI program-change data). Do not allow an orchestral preview program assignment to leak into the répétiteur MIDI. --- ## 13. Velocity and articulation principles The répétiteur is not intended to imitate a concert pianist. Its priorities are: 1. rhythmic clarity; 2. voice-leading clarity; 3. stable rehearsal pulse; 4. correct harmonic attacks; 5. tied-note continuity; 6. enough dynamic differentiation to avoid mechanical hammering. Do not use renderer-specific tricks to conceal incorrect notation. If articulation sounds wrong, first inspect: ```text score extraction tie interpretation MIDI note-on/off placement voicing velocity ``` before changing reverb, EQ, SoundFont, or post-processing. --- ## 14. Pedal policy Do not use sustain pedal as a substitute for correct tie handling. Pedal may be considered only if it improves the rehearsal sound without smearing contrapuntal detail. Default canonical assumption: ```text structural legato comes from correct MIDI durations/ties not from continuous sustain pedal ``` Any pedal layer introduced later should be explicit and reproducible. --- ## 15. Post-processing policy Default production principle: > Prefer the SoundFont render itself over a chain of corrective effects. Do not add undocumented: - EQ; - compression; - limiting; - reverb; - stereo widening; - loudness normalization. If post-processing becomes necessary, record the exact command/settings and apply the decision consistently across all movements. Player-side compression is a separate playback-system decision and must not be confused with alteration of the canonical accompaniment master. --- ## 16. File/version naming Version the musical reduction and rendered sound separately when appropriate. Example: ```text dixit_mvt3_repetiteur_piano_v1.mid ``` may remain the accepted note/timing master while the corrected common-timbre render becomes: ```text dixit_mvt3_repetiteur_piano_v2_FluidR3.wav ``` This means: ```text v1 MIDI = accepted musical reduction v2 audio = new render of that same accepted reduction ``` The version bump documents an audible production change without falsely implying that the score reduction was rewritten. --- ## 17. Reproduction workflow for a future movement For Movement 4 onward: ### Phase A — build the accompaniment 1. extract all relevant instrumental staves; 2. verify staff topology; 3. resolve clefs and accidentals; 4. identify ties; 5. identify tuplet candidates; 6. require exact bar closure; 7. decide: - sparse continuo → cautious harmonic realisation; - fully written texture → direct reduction; 8. produce rehearsal-piano MIDI; 9. regression-test ties and repeated harmony; 10. listen; 11. freeze the accepted MIDI. ### Phase B — render the canonical piano Use: ```bash fluidsynth -ni -g 0.6 \ /usr/share/sounds/sf2/FluidR3_GM.sf2 \ ACCEPTED.mid \ -F CANONICAL.wav \ -r 44100 ``` Then audition. ### Phase C — create the web stem Encode a derived MP3. Do not replace the canonical WAV with the MP3. ### Phase D — calibrate 1. install the web stem; 2. set a reference-derived starting hidden calibration; 3. compare against previous accepted movements; 4. adjust only the hidden calibration; 5. leave visible default at 70%; 6. freeze the accepted value in `movement.json`. --- ## 18. Regression checklist Before freezing a new accompaniment: ```text MUSICAL CONTENT [ ] literal instrumental bars all close [ ] no unexplained tuplet interpretations [ ] all confirmed ties survive into MIDI [ ] tied harmony is not falsely re-attacked [ ] accompaniment strategy matches score texture [ ] accepted MIDI has been auditioned independently RENDERING [ ] FluidSynth used [ ] exact FluidR3_GM.sf2 path used [ ] FluidSynth gain = 0.6 [ ] render sample rate = 44100 Hz [ ] explicit piano program is correct [ ] no undocumented pedal/effects/post-processing VERSIONING [ ] accepted reduction MIDI retained [ ] canonical WAV retained [ ] web MP3 treated as derivative [ ] timbre-only changes do not rewrite the MIDI PLAYER [ ] hidden calibration recalculated after any audio rerender [ ] visible mixer remains 70% default [ ] balance compared against accepted neighbouring movements [ ] calibration frozen only after listening ``` --- ## 19. Current production references ### Movement 1 — *Dixit Dominus* Established the FluidSynth / FluidR3_GM rendering family. Canonical rendering principle: ```text FluidSynth FluidR3_GM.sf2 44.1 kHz ``` ### Movement 2 — *Virgam virtutis tuae* Canonical sparse-continuo realisation example. Accepted accompaniment: ```text répétiteur piano v3 tie-aware FINAL ``` Accepted player calibration: ```text Piano 3.59 ``` Movement 2 also established the whole-texture tie rule: unchanged RH harmony must not create a false reattack over a tied bass. ### Movement 3 — *Tecum principium* Canonical fully written orchestral reduction example. Accepted musical reduction: ```text dixit_mvt3_repetiteur_piano_v1.mid ``` Accepted reduction architecture: ```text Violin I + Violin II + Viola I + Viola II ↓ upper piano texture continuo ↓ piano bass ``` The first piano render used a different timbre and was later superseded for project consistency. Accepted common-timbre rerender: ```text dixit_mvt3_repetiteur_piano_v2_FluidR3.wav ``` It reuses the accepted v1 MIDI unchanged and renders it through the same FluidSynth / FluidR3 chain as the preceding movements. This is the canonical example of separating **musical master** from **instrument-render master**. ### Movement 6 — *Dominus a dextris tuis* Accepted musical master: ```text dixit_mvt6_repetiteur_piano_v2.mid ``` Accepted canonical render: ```text /home/ajp/dixit/mvt6/dixit_mvt6_repetiteur_piano_v2.wav ``` Accepted rendering chain remains unchanged: ```text FluidSynth /usr/share/sounds/sf2/FluidR3_GM.sf2 -g 0.6 44100 Hz ``` Movement 6 established a new reduction rule for **exact simultaneous doubled orchestral unisons**. The literal v1 reduction retained both Vln I and Vln II when they struck the same pitch simultaneously, and likewise both Viola I and Viola II. A piano render then triggered the same piano key/sample twice at the same instant, creating artificial weight, especially at the full-tutti entrance around bar 81. Accepted v2 treatment: ```text within Vln I + Vln II: same attack time + same MIDI pitch -> one piano attack within Vla I + Vla II: same attack time + same MIDI pitch -> one piano attack ``` Keep all of the following distinct: ```text same-family exact unison duplication -> collapse cross-family pitch coincidence -> retain continuo coincidence -> retain true repeated note -> retain written tie -> sustain, no reattack ``` Movement-6 v2 audit: ```text logical attacks v1: 2215 logical attacks v2: 1686 duplicates removed: 529 before bar 81: 1 bars 81–148: 528 ``` This is not dynamic compression and not a player-side attenuation rule. It is a correction to the keyboard reduction itself. The accepted final player piano calibration is: ```text 1.7382 ``` at visible 70%. It was deliberately retained from the already satisfactory light first half after the v2 reduction was introduced; the bar-81 correction came from fixing note multiplicity rather than turning down the whole piano. Movement-6 timing: ```text 148 bars · 3/4 throughout · 100 BPM score/MIDI endpoint: 266.400 s FluidR3 WAV endpoint: 269.105 s renderer tail: 2.705 s ``` The natural FluidR3 tail is preserved rather than trimmed to the MIDI boundary. --- ## 20. Canonical rule summary ```text 1. Parse literally. 2. Require rhythmic closure. 3. Resolve ties before reduction. 4. Choose reduction strategy from the written texture. 5. Freeze the accepted accompaniment MIDI. 6. Render every accepted répétiteur through FluidSynth + FluidR3_GM.sf2. 7. Keep the canonical WAV. 8. Encode web audio only as a derivative. 9. Recalculate hidden calibration whenever the rendered audio changes. 10. Never regenerate musical content merely to change piano timbre. 11. In a piano reduction, collapse exact simultaneous same-pitch attacks from paired doubled orchestral staves when they represent one physical piano key; do not collapse cross-family coincidences or continuo. ``` That is the accompaniment/piano standard for the remainder of the project. --- ## 21. Movement 7 — *Judicabit* — piano v1 FINAL Movement 7 adds two extraction lessons before reduction. ### 21.1 Continuo clef changes are local score state The Continuo changes clef within systems. Pitch extraction therefore uses the latest active clef to the left of each note rather than a fixed staff-level clef. Canonical parser rule: ```text part default clef -> overridden by any printed in-staff clef change -> active until the next printed clef change ``` Do not allow a clef glyph from another system on the same PDF page to leak into the current system. Clef ownership must be constrained both by staff ownership and by vertical proximity to the current score system. ### 21.2 Polyphonic continuo bars validate by voice, not by summed duration Movement 7 Continuo contains genuine simultaneous written voices in: ```text bars 2, 3, 8, 13, 41, 42 ``` A monophonic bar-closure test therefore reports raw totals greater than four quarter notes: ```text bar 2 8.0 q bar 3 8.0 q bar 8 6.5 q bar 13 7.0 q bar 41 5.5 q bar 42 10.0 q ``` These are not malformed measures. The parser must separate simultaneous voices (e.g. by stem direction / voice topology) and validate each complete voice independently. For piano v1, the complete lower/bass voice is selected from each such measure: ```text bar 2 down-stem bass voice bar 3 down-stem bass voice bar 8 down-stem bass voice bar 13 down-stem bass voice + written rests bar 41 up-stem bass voice bar 42 down-stem bass voice ``` The resulting selected Continuo bass closes exactly in all 61 measures. ### 21.3 Literal extraction audit Movement 7 score: ```text 61 bars 4/4 throughout 100 BPM rehearsal tempo one-flat key signature exact score duration = 146.400 s ``` Literal instrumental extraction: ```text Violin I 594 events / 538 pitched notes Violin II 594 events / 538 pitched notes Viola I 384 events / 304 pitched notes Viola II 383 events / 304 pitched notes Violoncello/Bass 81 events / 67 pitched notes Continuo 409 events / 383 pitched notes ``` Upper strings close exactly in all 61 bars. The separate Violoncello/Bass staff is useful as an audit of the Continuo bass where it is present, but the reduction uses the Continuo bass line so that passages where the orchestral bass rests but keyboard continuo continues are preserved. ### 21.4 Reduction architecture Movement 7 is a fully written orchestral-texture case: ```text Violin I + Violin II -> upper piano texture Viola I + Viola II -> upper piano texture selected written Continuo bass voice -> lower piano texture ``` No new harmony is invented. Movement-6 same-family exact-unison collapse remains in force: ```text within Violin I + II: same attack + same MIDI pitch -> one piano attack within Viola I + II: same attack + same MIDI pitch -> one piano attack cross-family coincidence -> retain continuo coincidence -> retain true repeated note -> retain written tie -> sustain ``` Movement-7 v1 reduction audit: ```text upper-string logical spans before same-family collapse: 1684 upper-string attacks after collapse: 1170 same-family duplicate attacks removed: 514 Continuo-bass logical spans: 360 total reduction attacks: 1530 ``` Accepted musical master: ```text dixit_mvt7_repetiteur_piano_v1.mid ``` The unchanged v1 MIDI was subsequently rendered through the canonical FluidR3 chain, accepted by listening, and promoted to FINAL. ### 21.5 Historical preview render was not the canonical timbre During construction, a convenience preview was rendered through: ```text TimGM6mb.sf2 44.1 kHz gain 0.6 ``` Preview files: ```text dixit_mvt7_repetiteur_piano_v1_PREVIEW_TimGM6mb.wav dixit_mvt7_repetiteur_piano_v1_PREVIEW_TimGM6mb.mp3 ``` That preview was never promoted as a canonical master. The accepted unchanged MIDI was later rendered using the project-standard chain: ```bash fluidsynth -ni -g 0.6 \ /usr/share/sounds/sf2/FluidR3_GM.sf2 \ dixit_mvt7_repetiteur_piano_v1.mid \ -F dixit_mvt7_repetiteur_piano_v1.wav \ -r 44100 ``` The FluidR3 render was accepted. Movement-7 final timing and player calibration are: ```text score/MIDI endpoint: 146.400 s FluidR3/player endpoint: 148.402 s renderer tail: 2.002 s Piano hidden calibration: 2.3179 ``` Movement 7 piano v1 is therefore FINAL. --- ## 22. Movement 8 — *Conquassabit* — piano v1 FINAL Movement 8 confirms the Movement-6/7 direct-written-reduction architecture and adds a useful system-ownership regression case. ### 22.1 Literal instrumental extraction Movement 8 score: ```text 50 bars 3/4 throughout 100 BPM rehearsal tempo one-flat key signature (B-flat only) exact score/MIDI duration = 90.000 s ``` Accepted literal instrumental extraction: ```text Violin I 207 events / 198 sounding Violin II 200 events / 192 sounding Viola I 169 events / 145 sounding Viola II 170 events / 147 sounding Continuo 189 events / 171 sounding ``` Pitch ranges: ```text Violin I/II F4..C6 Viola I C4..D5 Viola II G3..A4 Continuo D2..D4 ``` There are zero instrumental ties in this movement, and every instrumental staff closes to exactly three quarter-note units in every bar. ### 22.2 Clef ownership requires both staff identity and current-system geometry The final Movement-8 system shares a PDF page with the beginning of Movement 9. An early extraction accidentally associated a lower-system Movement-9 treble clef with the Movement-8 Continuo. Canonical rule: ```text candidate clef must: belong to the named staff AND lie within / immediately relevant to the current score system ``` Do not resolve ownership by horizontal position alone on a page containing more than one score system or movement. ### 22.3 Accepted direct reduction and same-family collapse Movement 8 uses: ```text Violin I + Violin II -> upper piano family Viola I + Viola II -> upper piano family written Continuo -> lower piano family ``` No harmony is invented. Same-family exact simultaneous same-pitch spans collapse to one piano attack: ```text Violin spans before collapse: 390 duplicates removed: 67 Violin attacks after collapse:323 Viola spans before collapse: 292 duplicates removed: 9 Viola attacks after collapse: 283 Continuo attacks retained: 171 --- total piano note-ons: 777 ``` Cross-family coincidences remain separate. Continuo coincidences remain separate. True repeated attacks remain attacks. This rule represents one physical piano key and must not be confused with synthetic-vocal phase management. Vocal parts remain distinct performers even when their rendered waveforms need timing decorrelation. ### 22.4 Accepted musical master Canonical MIDI: ```text dixit_mvt8_repetiteur_piano_v1.mid ``` SHA-256: ```text 24f1bf0283d24c4813e5fa56aad756e23dd7f658754a0fb2d7eb066f62e09690 ``` The accepted render uses the canonical chain: ```bash fluidsynth -ni -g 0.6 \ /usr/share/sounds/sf2/FluidR3_GM.sf2 \ dixit_mvt8_repetiteur_piano_v1.mid \ -F dixit_mvt8_repetiteur_piano_v1.wav \ -r 44100 ``` Final timing: ```text score/MIDI endpoint: 90.000 s FluidR3/player endpoint: 92.704 s renderer tail: 2.704 s ``` Final piano hidden calibration at visible 70%: ```text 1.5852 ``` Movement 8 piano v1 is FINAL. ### 22.5 Cross-layer rule established by Movement 8 Three superficially similar “doubling” problems now have different canonical solutions: ```text paired orchestral staves hit the same piano key -> collapse within family in the reduction MIDI two cloned synthetic vocal instances have phase-correlated waveforms -> retain both written voices; decorrelate one with a fixed accepted micro-timing realization in the canonical USTX two vocal parts substantially double the same written line -> retain both voices; use light passage attenuation where musically needed ``` Never solve one of these at the wrong layer.