From 645b396ef9509257a896f0df5610e846f54b79a5 Mon Sep 17 00:00:00 2001 From: skal Date: Wed, 4 Feb 2026 13:42:21 +0100 Subject: docs: Milestone state snapshot - Audio system robustness complete Documented completion of major audio system improvements: - Task #51: Tracker timing verification (0.000ms sync confirmed) - Variable tempo system (6 tests, all passing) - Zero production size impact (all test code under !STRIP_ALL) Key achievements: - Perfect audio synchronization verified - Dynamic tempo control ready (music_time abstraction) - Comprehensive test coverage (16/16 tests passing) - Mathematical precision verified for reset tricks Updated: - PROJECT_CONTEXT.md: Added milestone section - HANDOFF_2026-02-04.md: Complete state snapshot for handoff System ready for: - Dynamic tempo animation - Physics & collision (Task #49) - 3D scene pipeline (Task #18) handoff(Claude): Audio milestone complete, state saved Co-Authored-By: Claude Sonnet 4.5 --- HANDOFF_2026-02-04.md | 219 ++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 219 insertions(+) create mode 100644 HANDOFF_2026-02-04.md (limited to 'HANDOFF_2026-02-04.md') diff --git a/HANDOFF_2026-02-04.md b/HANDOFF_2026-02-04.md new file mode 100644 index 0000000..f38e5be --- /dev/null +++ b/HANDOFF_2026-02-04.md @@ -0,0 +1,219 @@ +# Handoff: Audio System Milestone (February 4, 2026) + +## Summary +Completed comprehensive audio system robustness improvements including tracker timing verification and variable tempo implementation. + +## What Was Accomplished + +### Task #51: Tracker Timing Verification System +**Goal**: Create robust testing infrastructure to verify audio synchronization. + +**Implementation**: +- Created `AudioBackend` interface (`src/audio/audio_backend.h`) separating synthesis from output +- Implemented `MiniaudioBackend` for production use +- Implemented `MockAudioBackend` for testing with event recording +- Added time tracking to `synth.cc` (32kHz sample rate precision) +- Created comprehensive test suite (`test_tracker_timing.cc`) + +**Key Finding**: ✅ Simultaneous pattern triggers have **0.000ms delta** (perfect sync verified) + +**Files**: +- `src/audio/audio_backend.h` (interface) +- `src/audio/miniaudio_backend.{h,cc}` (production backend) +- `src/audio/mock_audio_backend.{h,cc}` (test backend, under `!STRIP_ALL`) +- `src/audio/audio.cc` (refactored to use backends) +- `src/audio/synth.cc` (added time tracking hooks) +- `src/tests/test_audio_backend.cc` (3 tests) +- `src/tests/test_mock_backend.cc` (6 tests) +- `src/tests/test_tracker_timing.cc` (7 tests) + +**Test Results**: 13 → 16 tests passing (100% success rate) + +### Variable Tempo System +**Goal**: Enable dynamic tempo changes without pitch shifting or BPM dependencies. + +**Design Philosophy**: +- Don't modify spectrograms or synthesis engine +- Only change WHEN patterns trigger (not HOW they sound) +- Simple: `music_time += dt * tempo_scale` + +**Implementation**: +- Added `g_music_time`, `g_tempo_scale`, `g_last_physical_time` to `main.cc` +- Modified `update_game_logic` to calculate delta time and advance music_time +- Changed `tracker_update((float)t)` → `tracker_update(g_music_time)` +- Created test suite (`test_variable_tempo.cc`) with 6 scenarios + +**Test Coverage**: +1. Basic tempo scaling (1.0x, 2.0x, 0.5x) ✅ +2. 2x speed-up reset trick (accelerate to 2.0x, reset to 1.0x) ✅ +3. 2x slow-down reset trick (decelerate to 0.5x, reset to 1.0x) ✅ +4. Pattern density swap at reset points ✅ +5. Continuous acceleration (0.5x to 2.0x over 10s) ✅ +6. Oscillating tempo (sine wave modulation) ✅ + +**Key Results**: +- After 5s physical at 2.0x tempo: `music_time=7.550s` (expected ~7.5s) ✅ +- Reset to 1.0x, advance 2s: `music_time delta=2.000s` (expected ~2.0s) ✅ +- All mathematical predictions verified with <0.1s tolerance + +**Files**: +- `src/main.cc` (~15 lines added) +- `src/tests/test_variable_tempo.cc` (376 lines, 6 tests) +- `ANALYSIS_VARIABLE_TEMPO.md` (original complex approach) +- `ANALYSIS_VARIABLE_TEMPO_V2.md` (simplified approach - implemented) + +## Current State + +### Build Status +- ✅ All 16 tests passing (100% success rate) +- ✅ Clean build with no warnings +- ✅ Zero size impact on stripped builds (`STRIP_ALL`) + +### Audio System +- ✅ Backend abstraction layer working +- ✅ Mock backend for deterministic testing +- ✅ Perfect audio synchronization verified (0.000ms delta) +- ✅ Variable tempo ready for dynamic control +- ✅ No pitch shifting artifacts + +### Ready for Next Steps +The audio system is now robust and ready for: +- Dynamic tempo control during playback (animate `g_tempo_scale`) +- "Reset trick" implementation (accelerate/slow + pattern density swap) +- Tempo curves (linear, exponential, oscillating, manual) +- Integration with visual sync and beat detection + +## Technical Details + +### Music Time Formula +```cpp +// Physical time → Music time +float dt = current_time - last_time; +music_time += dt * tempo_scale; + +// Examples: +// tempo_scale=1.0 → music_time advances at normal rate +// tempo_scale=2.0 → music_time advances 2x faster (patterns trigger sooner) +// tempo_scale=0.5 → music_time advances 2x slower (patterns trigger later) +``` + +### Reset Trick Pattern +```cpp +// Phase 1: Accelerate +tempo_scale = 1.0f + (time / 5.0f); // Linear acceleration +if (tempo_scale >= 2.0f) tempo_scale = 2.0f; + +// Phase 2: Reset +if (tempo_scale >= 2.0f) { + tempo_scale = 1.0f; // Reset to normal + // Switch to 2x denser pattern to maintain perceived tempo +} +``` + +### MockAudioBackend API +```cpp +// Record events +void on_voice_triggered(float timestamp, int spectrogram_id, + float volume, float pan) override; + +// Time management +void on_frames_rendered(int num_frames) override; +float get_current_time() const; + +// Test queries +const std::vector& get_events() const; +void clear_events(); +``` + +## Commits Made + +1. `c4888be` - feat(audio): Audio backend abstraction layer (Task #51.1) +2. `bb49daa` - feat(audio): Mock audio backend for testing (Task #51.2) +3. `215a4d8` - feat(audio): Tracker timing test suite (Tasks #51.3 & #51.4) +4. `a09e36b` - docs: Variable tempo architecture analysis +5. `829e211` - docs: Simplified variable tempo approach (V2) +6. `25d7e4e` - feat(audio): Variable tempo system with music time abstraction + +## Documentation Updated +- ✅ `TODO.md` - Marked Task #51 complete, added variable tempo section +- ✅ `PROJECT_CONTEXT.md` - Added milestone to "Recently Completed" +- ✅ `ANALYSIS_VARIABLE_TEMPO.md` - Original complex analysis +- ✅ `ANALYSIS_VARIABLE_TEMPO_V2.md` - Simplified approach (implemented) +- ✅ `HANDOFF_2026-02-04.md` - This document + +## Next Steps (Recommendations) + +### Immediate (Optional) +- Add tempo control API (`set_tempo_scale()`, `get_tempo_scale()`, `get_music_time()`) +- Expose tempo control to demo sequence system +- Test with actual demo playback + +### Priority 1: Physics & Collision (Task #49) +- Implement CPU-side SDF library +- Build BVH for acceleration +- Create physics loop with collision resolution + +### Priority 2: 3D System Enhancements (Task #18) +- Blender exporter script +- Asset ingestion for 3D scenes +- Runtime scene loader + +## Notes for Next Developer + +### Testing Strategy +- All audio tests use `MockAudioBackend` for deterministic verification +- Use `audio_set_backend(&mock)` before tests +- Check `get_events()` for voice trigger timing +- Compare timestamps with expected values (<1ms tolerance) + +### Variable Tempo Usage +```cpp +// In main loop or sequence system +extern float g_tempo_scale; // Declared in main.cc +g_tempo_scale = 1.5f; // 1.5x faster playback + +// For gradual acceleration +g_tempo_scale = 1.0f + (time / 10.0f); // Accelerate over 10s + +// For reset trick +if (g_tempo_scale >= 2.0f) { + g_tempo_scale = 1.0f; + trigger_denser_pattern(); +} +``` + +### Code Philosophy +- Keep spectrograms unchanged (size optimization) +- All timing in "music time" space +- Physical time only for delta calculation +- Zero production overhead (`!STRIP_ALL` guards) + +## Verification Commands + +```bash +# Build and test +cmake --build build +cd build && ctest + +# Coverage report +./scripts/gen_coverage_report.sh src/audio + +# Size check (stripped build) +cmake -S . -B build_strip -DDEMO_STRIP_ALL=ON +cmake --build build_strip +ls -lh build_strip/demo64k* +``` + +## Status: MILESTONE COMPLETE ✅ + +All objectives achieved: +- ✅ Audio synchronization verified (0.000ms delta) +- ✅ Variable tempo system implemented and tested +- ✅ Zero production size impact +- ✅ 100% test pass rate +- ✅ Documentation complete +- ✅ Ready for next phase + +--- +*Generated: February 4, 2026* +*Claude Sonnet 4.5* -- cgit v1.2.3