| 311 | } |
| 312 | |
| 313 | void Downbeat::detectMeter() { |
| 314 | // Analyze recent beat patterns to detect time signature |
| 315 | // Look for recurring patterns in beat intervals and accents |
| 316 | |
| 317 | // Add current meter candidate based on beat count |
| 318 | u8 detectedMeter = mBeatsPerMeasure; |
| 319 | |
| 320 | // Analyze accent patterns to infer meter |
| 321 | if (mBeatAccents.size() >= 8) { |
| 322 | // Look for recurring strong accents |
| 323 | // Common meters: 4/4 (every 4 beats), 3/4 (every 3), 6/8 (every 6) |
| 324 | |
| 325 | size numAccents = mBeatAccents.size(); |
| 326 | fl::array<u8, 5> candidateMeters = {2, 3, 4, 6, 8}; |
| 327 | float bestScore = 0.0f; |
| 328 | u8 bestMeter = 4; |
| 329 | |
| 330 | for (size m = 0; m < candidateMeters.size(); m++) { |
| 331 | u8 meter = candidateMeters[m]; |
| 332 | float score = 0.0f; |
| 333 | |
| 334 | // Score based on accent pattern matching |
| 335 | for (size i = 0; i < numAccents; i++) { |
| 336 | if (i % meter == 0) { |
| 337 | // Expect strong accent at measure start |
| 338 | score += mBeatAccents[i]; |
| 339 | } else { |
| 340 | // Expect weaker accent elsewhere |
| 341 | score += (2.0f - mBeatAccents[i]) * 0.5f; |
| 342 | } |
| 343 | } |
| 344 | |
| 345 | if (score > bestScore) { |
| 346 | bestScore = score; |
| 347 | bestMeter = meter; |
| 348 | } |
| 349 | } |
| 350 | |
| 351 | detectedMeter = bestMeter; |
| 352 | } |
| 353 | |
| 354 | // Add to meter history |
| 355 | if (mMeterCandidates.size() >= METER_HISTORY_SIZE) { |
| 356 | mMeterCandidates.pop_front(); |
| 357 | } |
| 358 | mMeterCandidates.push_back(detectedMeter); |
| 359 | |
| 360 | // Find most common meter in recent history |
| 361 | u8 consensusMeter = findMostCommonMeter(); |
| 362 | |
| 363 | // Update meter if consensus differs and is stable |
| 364 | if (consensusMeter != mBeatsPerMeasure && mMeterCandidates.size() >= METER_HISTORY_SIZE / 2) { |
| 365 | (void)mBeatsPerMeasure; // Suppress unused warning (used in comparison above) |
| 366 | mBeatsPerMeasure = consensusMeter; |
| 367 | |
| 368 | // Set meter change callback flag |
| 369 | mFireMeterChange = true; |
| 370 | mPendingMeter = mBeatsPerMeasure; |