From db6fbf8b8eae8b96d129ac673cbf11d67926996a Mon Sep 17 00:00:00 2001 From: skal Date: Thu, 5 Mar 2026 22:49:48 +0100 Subject: fix(audio): correct OLA synthesis and extract shared ola_encode/ola_decode - Remove erroneous Hann synthesis window from synth.cc (g_hann * tmp[j]). Hann analysis at 50% overlap satisfies w[n]+w[n+H]=1, so rectangular synthesis gives perfect reconstruction; applying Hann twice was wrong. - Extract ola_encode()/ola_decode()/ola_num_frames() into src/audio/ola.h+cc. spectool and test_wav_roundtrip now use the shared functions. synth.cc lazy-decode path stays inlined (see TODO for future refactor). - Drop dead include and g_hann array from synth.cc. - Drop dead window.h include from spectool.cc. - Update PROJECT_CONTEXT.md, COMPLETED.md, TODO.md to reflect correct analysis-only Hann window and new ola.h API. handoff(Gemini): OLA synthesis bug fixed + ola.h factorized. synth.cc lazy-decode still inline (TODO item added). 34/35 tests pass; WavDumpBackendTest failure is pre-existing and unrelated. Co-Authored-By: Claude Sonnet 4.6 --- TODO.md | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) (limited to 'TODO.md') diff --git a/TODO.md b/TODO.md index 45623e8..c87fbc2 100644 --- a/TODO.md +++ b/TODO.md @@ -36,7 +36,12 @@ Reduce weights from f16 (~3.2 KB) to i8 (~1.6 KB). ## Priority 4: Audio System Enhancements [LOW PRIORITY] -1. **GPU-Accelerated PCM Synthesis:** +1. **`synth.cc`: use `ola_decode()` from `src/audio/ola.h`** — the OLA decode logic in + `synth_render()` is currently inlined for frame-by-frame lazy decoding. Refactor to + call `ola_decode()` for consistency with `spectool` and the test (requires decoupling + the per-frame lazy path, e.g. decode a full block on demand then serve samples). + +2. **GPU-Accelerated PCM Synthesis:** - Compute shader for direct PCM generation (bypass spectrogram) - Write to compute buffer, readback to synth -- cgit v1.2.3