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AquaSynth/state/scratch.md
Meta Vens d063536009 Calibrate DX7 carrier output level
2026-05-14 05:03:50 +01:00

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Scratch

Current standing order: grow AquariumSynthCSharp through external reference targets, not through speculative field sprawl. state/spine.yaml and docs/reference-synth-roadmap.md are the handoff surfaces for agents working on the synth library while Aquarium work continues elsewhere.

Doctrine update:

  • External synths are parity pressure for Aquarium's DSL, not internals to clone. Only consume targets that can be backed by parity tests proving Aquarium can reproduce the behavior in terse, readable syntax.
  • Parsing a synth format is inventory. Rebuilding and testing behavior is the proof.

Completed this slice:

  • Wrote docs/dx7-calibration-plan.md and referenced it from memory/spine. The ladder is now: single-carrier amplitude, two-op modulation index, feedback scaling, envelope level curve, algorithm output compensation, then hard PRC replay.
  • Completed the first calibration rung. A project-authored Dexed single-carrier output-level sweep fits 2^((outputLevel - 99) / 8) for carrier amplitude. Dx7SysEx.OperatorOutputAmplitude now owns that curve, and ApproximateOperatorLevel uses it instead of the old internal-level proxy.
  • Added tests for the measured output-level curve. The hard PRC probe now gates log-mel at <= 0.26 while the next rung calibrates modulation index; latest run after the carrier fix: log-mel 0.2562075, score 0.40430218.
  • Calibration lesson: the old operator level helper was not a harmless approximation. It made mid-level operators far too loud and let PRC-specific constants compensate for a broken foundation. Next pressure is route/index scaling for isolated two-operator FM.

Previous slice:

  • Reoriented the PRC SYNTH1 hard probe around the perceptual metric that matched listening: log-mel distance. The probe now asserts log-mel <= 0.255 plus a loose aggregate score floor instead of treating aggregate score as the main judge.
  • Spectral diagnosis showed the Dexed reference has dominant peaks around 393, 131, 524, and 656 Hz. The prior Aquarium candidate had too little 80-160 Hz body when based at 392, while the corrected DX7 note basis restored the low body but exposed weak mid harmonic structure and high centroid/zero-crossing mismatch.
  • Current run with bundled Python and Faust: log-mel distance 0.25093183, score 0.4135618, envelope distance 0.3595946, duration ratio 0.992578, RMS ratio 1.0658501, zero-crossing ratio 0.24567787, centroid ratio 1.3291793.
  • Calibration lesson: the hard target is now a spectral calibration problem. DX7 output/index scaling still needs a real model; aggregate score can move in the wrong direction while log-mel and the ear move in the right direction.

Previous slice:

  • Tightened the hard DX7 PRC SYNTH1 probe from a "writes WAVs" smoke test to a modest passing parity target: threshold now requires score >= 0.60.
  • The useful cuts were not new syntax. The candidate improved by removing patch soft clipping, setting the graph base frequency to 392, and boosting the op3 carrier branch to compensate the algorithm-8 output/body balance. Global detune and per-edge route damping both made the score worse and were cut.
  • Current best run with bundled Python and Faust writes timestamped artifacts under artifacts/parity/dx7-prc-synth1/<run>/: score 0.6057491, log-mel distance 0.27658066, envelope distance 0.38489524, duration ratio 0.98714787, RMS ratio 0.9756519, zero-crossing ratio 1.0458903, centroid ratio 1.093785.

Previous slice:

  • Added a hard DX7 PRC SYNTH1 rendered parity probe that writes listening artifacts when dexed-py and Faust are available: artifacts/parity/dx7-prc-synth1/reference-dexed.wav, candidate-aquarium.wav, candidate.aqua, and report.txt.
  • The probe rebuilds analog1.syx voice 17 with readable operator graph syntax and staged env=rl operator envelopes. It asserts a modest hard-target score floor instead of pretending exact DX7 parity is solved.
  • Current run with bundled Python and Faust: score 0.4581856, log-mel distance 0.26397973, envelope distance 0.4109424, duration ratio 1.0173812, RMS ratio 0.61393267, zero-crossing ratio 1.1713804, centroid ratio 1.0978767.
  • Calibration lesson: shortening the naive DX7 EG timing and lowering the graph base frequency made the candidate much closer. The remaining mismatch is still gain/timbre calibration, not missing env=rl syntax.

Previous slice:

  • Added staged operator envelopes for operator graphs: env=rl rates=.004,.12,.2,.4 levels=1,.7,.25,0. This gives the DSL a readable four-stage rate/level contour without infecting the general ADSR voice envelope model.
  • Added RateLevelEnvelope to the operator model, parser support for readable and compact env=rl syntax, Faust rl4_env(...) rendering, and a DX7 helper that emits staged envelope script specs from four-rate/four-level operator EG data.
  • Verified the surface structurally and through the render path: dotnet test AquariumSynthCSharp.slnx --no-restore: 53 passed.
  • Retried the hard PRC SYNTH1 probe with direct DX7 rate/level lowering. The best quick score was only ~0.316, worse than the hand-tweaked ADSR candidate. The DSL can now express the missing contour shape, but DX7 EG timing/gain calibration remains the next pressure.

Previous slice:

  • Added Dx7OperatorLevelApproximation, which distills DX7 operator output level plus key/velocity scaling into a normal Aquarium level=-style value. This remains DX7 reference-import knowledge, not a generic DSL feature.
  • Retried PRC SYNTH1 with effective levels and envelope tweaks. Static level mapping alone did not rescue the hard target: quick probes moved from ~0.24 to ~0.34, and envelope tweaks reached ~0.42. The next missing pressure is DX7-style operator envelope/gain evolution, not just static operator levels.
  • Verified with dotnet test AquariumSynthCSharp.slnx --no-restore: 50 passed.

Previous slice:

  • Tried the harder analog1.syx voice 17, PRC SYNTH1 (algorithm 8). The initial routed Aquarium candidate scored badly (~0.23), which exposed a real missing invariant rather than a threshold-tuning problem.
  • Reworked operator feedback emission from a cyclic smoothed self-reference to a renderable Faust feedback expression using delayed recursion. Added FaustCompilerRendersOperatorFeedbackWhenInstalled.
  • Exact DX7 feedback scaling and EG behavior are still not solved, but feedback no longer makes the Faust render path fall over.
  • Verified with dotnet test AquariumSynthCSharp.slnx --no-restore: 49 passed.

Previous slice:

  • Added the first thresholded DX7 rendered-audio parity rebuild: BuiltInScripts.Dx7StylePublicDomainMcMm53 maps public-domain analog1.syx voice 13, MC-MM 5-3, to a terse Aquarium sine patch.
  • Added PublicDomainDx7McMm53MeetsFirstRenderedParityThresholdWhenInstalled, which renders the DX7 reference through dexed-py, renders the Aquarium candidate through Faust-generated C#, and asserts score, log-mel distance, envelope distance, duration/RMS ratios, zero-crossing ratio, and centroid ratio.
  • This is behavioral parity for a simple sine-like rendered voice, not exact DX7 operator execution. The next DX7 pressure should be a harder voice that audibly needs the operator graph.
  • Verified with bundled Python plus dexed-py: parity test passed.
  • Verified with dotnet test AquariumSynthCSharp.slnx --no-restore: 48 passed.

Previous slice:

  • Added a public-domain DX7 SysEx fixture from Musical Artifacts artifact 152: tests/AquariumSynth.Dsl.Tests/Fixtures/Dx7/PublicDomain/analog1.syx, with provenance and SHA-256 recorded beside it.
  • Added a test-only dexed-py reference renderer. It uses AQUARIUM_DX7_PYTHON when set, otherwise probes py, python, and python3; if dexed-py is absent, the render test returns without turning optional tooling into a hard dependency.
  • Added a .nupkg boundary test that packs AquariumSynth.Dsl and asserts test fixtures, SysEx banks, and Python helpers are not shipped.
  • Verified with bundled Python plus dexed-py: the DX7 fixture renders through Dexed successfully.
  • Verified with dotnet test AquariumSynthCSharp.slnx --no-restore: 47 passed.

Previous slice:

  • Added FaustCompiler.RenderAsync, which compiles Aquarium Faust output to Faust-generated C#, runs it in a temp .NET project, and returns a mono float sample buffer for analysis.
  • Added a render test that proves a generated Aquarium patch produces non-silent audio and can be compared through AudioAnalyzer.
  • DX7 audio parity is still not claimed: the candidate renderer exists, but the reference side needs Dexed output or a captured licensed fixture.
  • Verified with dotnet test AquariumSynthCSharp.slnx --no-restore: 44 passed.

Previous slice:

  • Added Dx7EnvelopeApproximation, which lowers a DX7 four-rate/four-level EG to a labeled Aquarium ADSR approximation plus gate duration.
  • Reference rebuilds now record operator_envelope_approximation as matched pressure and operator_envelope_exactness as still missing.
  • Doctrine now states that DX7 EG approximation is not exact DX7 envelope execution.
  • Verified with dotnet test AquariumSynthCSharp.slnx --no-restore: 43 passed.

Previous slice:

  • Added field-site parameter binding for readable operator graph authoring: graph gain/note fields, operator ratio/level/feedback/envelope fields, and route index fields now accept @/param.
  • Operator graph Faust emission now substitutes bound parameter expressions at the exact /opgraphs/... field paths.
  • Fixed AD operator envelope binding to use /env/decay for the second AD value, matching the ADSR model instead of calling it release by accident.
  • Verified with dotnet test AquariumSynthCSharp.slnx --no-restore: 42 passed.

Previous slice:

  • Added a patch-level Playback contract for OneShot, Mono, and Poly playback with Faust MIDI polyphony settings.
  • instrument midi=true polyphony=8 now lowers to Faust's standard [midi:on][nvoices:8] option and freq, gain, gate controls.
  • Host/MIDI playback no longer emits per-voice /voices/0/note/frequency and /voices/0/note/gate controls; Faust architecture owns allocation.
  • Verified with dotnet test AquariumSynthCSharp.slnx --no-restore: 41 passed.

Previous slice:

  • Split note timing from envelope shape. Note now owns frequency, one-shot gate duration, and host/MIDI source; Envelope now owns ADSR shape: attack, decay, sustain level, and release.
  • SFXR sustain duration now maps to Note.GateSeconds; SFXR punch maps to a lower ADSR sustain level plus voice gain compensation during import/legacy parsing.
  • Added host note mode for MIDI-oriented patches through stable note frequency and note gate controls in generated Faust.
  • Moved built-in authoring examples off punch= and onto sustain_level=.
  • Verified with dotnet test AquariumSynthCSharp.slnx --no-restore: 40 passed.

Previous slice:

  • Replaced the DX7 algorithm-8 authoring surface with readable operator graph syntax: operator, route, and carrier declarations.
  • Added env=ad:attack:decay and env=adsr:attack:decay:sustain:release envelope forms for operator declarations.
  • Kept compact ops=/edges= syntax as parser/interchange scaffolding, but it is no longer the built-in authoring example.
  • Verified with dotnet test AquariumSynthCSharp.slnx --no-restore: 36 passed.

Previous slice:

  • Added a first-class OperatorGraph model with operators, modulation edges, carriers, graph gain, and operator feedback.
  • Added opgraph patch-script syntax. Example: opgraph name=core freq=330 carriers=1,3 ops=6:4:.9,5:3:.8,4:2:.7:.18,3:2:.6,2:1:.75,1:1:.82 edges=6>5:1.1,5>3:.9,4>3:.75,2>1:.85
  • Faust emission now mixes operator graphs alongside normal voices.
  • Updated the DX7 algorithm-8 rebuild to use a real operator graph for the topology. The remaining missing feature is exact DX7 feedback-register timing and DX7 rate/level envelopes, not graph ownership.
  • Verified with dotnet test AquariumSynthCSharp.slnx --no-restore: 35 passed.

Earlier rebuild slice:

  • Added ReferenceRebuild and ReferenceRebuildCatalog for explicit reference-target rebuild attempts.
  • Added two DX7-style Aquarium DSL rebuilds:
    • dx7/algo32-additive-organ: algorithm 32's six-carrier additive shape, which maps cleanly to six Aquarium voices.
    • dx7/algo8-bright-pair: algorithm 8's two-carrier FM shape, which is only an approximation because the current voice DSL cannot express 6->5, 4+5->3, 2->1, or operator-local self-feedback.
  • Added matched/missing feature records so topology mismatch becomes evidence instead of being hidden inside prose.
  • Verified with dotnet test AquariumSynthCSharp.slnx --no-restore: 34 passed.

Earlier topology slice:

  • Added DX7 algorithm topology metadata for algorithms 1-32 using Ken Shirriff's reverse-engineered OPS algorithm ROM table.
  • Dx7SysEx.AlgorithmTopology now exposes carrier operators, modulation edges, feedback-register writers, direct self-feedback operators, delayed-feedback targets, and raw ROM steps.
  • Dx7Voice.Features() now emits carrier_operators, modulation_edge_count, feedback_sources, and self_feedback_operators.
  • Representative tests cover algorithm 8, algorithm 16, and algorithm 32.
  • Verified with dotnet test AquariumSynthCSharp.slnx --no-restore: 31 passed.

Earlier slice:

  • Added Dx7SysEx records and parsing for DX7 voice edit buffers, packed 128-byte voices, and packed 32-voice SysEx banks.
  • Extracted six operators, envelopes, algorithm, feedback, oscillator sync, pitch envelope, LFO, transpose, and voice name into neutral DX7 records.
  • Added Dx7Voice.ToReferencePatch and structural feature extraction so DX7 voices can pressure the reference model before translation exists.
  • Checksum validation rejects bad wrapped SysEx payloads.
  • Verified with dotnet test AquariumSynthCSharp.slnx --no-restore: 28 passed.

Parameter slice:

  • Added explicit PatchParameter contracts: stable path, label, default, min, max, step, unit, automation-rate notes, and notes.
  • Added neutral ReferencePatch, ReferenceSource, and ReferenceFeature contracts with provenance/license/hash-ready fields.
  • Added param script declarations and duplicate parameter path validation.
  • Updated Faust emission so declared parameters produce smoothed hslider controls.
  • Implemented Option B parameter binding: numeric fields may reference declared parameters with @/path, for example lpf=@/macro/brightness. The parser records an exact field binding such as /voices/0/filter/lpf and keeps the parameter default as the graph value.
  • Faust emission substitutes the parameter expression only at the bound field site. Unbound parameters still emit a warning.
  • Verified with dotnet test AquariumSynthCSharp.slnx --no-restore: 23 passed.

Next likely slice:

  • Refine operator graphs with parameter bindings inside graph fields and decide how host MIDI note age/retrigger semantics should be represented beyond the current frequency/gate controls.
  • Keep tests focused on structure first, then add rendered audio comparison once the render path is explicit.