Clipture 1.5.4: Audio Mixer Quantization & 100 Hz Buzz Elimination

[1.5.4] - 2026-09-11

Audio Mixer Quantization & 100 Hz Buzz Elimination

• Nearest-Sample Grid Quantization: Replaced truncating integer division in AudioReplayCoordinator with a dedicated nearest-sample rounding implementation (PcmBlockMixer.hpp). Truncation toward zero previously placed adjacent packets (-479.995 frames and +0.005 frames) into the same output frame index zero, causing an artifactual doubled sample every 480 frames and pumping the peak limiter at the 100 Hz mix-block cadence.
• Consistent Half-Frame Tie Breaking: Standardized boundary tie breaking toward the later frame across negative and positive fractional offsets, ensuring continuous sample flow across 8 kHz, 44.1 kHz, 48 kHz, and 96 kHz streams even after sub-millisecond clock adjustments.
• Audio Integration & Phase Sweep Test Coverage: Added clipture_pcm_block_mixer unit tests verifying boundary phase continuity across sample sweeps and multi-track summation, alongside testAudioMixerClockPhaseDoesNotChangeAac validating that fractional clock phase corrections do not alter AAC stream encodings.