SOUNDFIELD / VIEWPORT

powered off

Load .mp4 / .iamf / WAV roll 0°

drag = rotate view · click = place synth source · arrows = rotate · R = reset

view yaw

0°

view pitch

0°

source az / el

+90° / 0°

ILD L−R

—

-inf

Pipeline: ambiX (ACN/SN3D) 4/9/16 ch (zero-padded to order 3) → libspatialaudio 0.4 AmbisonicRotator (30 ms coefficient fade) → MagLS SH-domain binaural (complex-LS <1.5 kHz / magnitude-LS above, 16×2 FIR 512 taps, overlap-add) → stereo out. All DSP in an AudioWorklet running the WASM build. HRTF: Neumann KU100, SADIE II database v2-2 (D1, 8802 points, 48 kHz), © University of York, Apache 2.0 — Armstrong, Thresh & Kearney, doi:10.3390/app8112029.
Inputs: 360/180 MP4 with an 'iamf' audio track (video via <video>+WebGL rectilinear projection, audio demuxed and decoded here, drift-corrected sync, worst-case tail gap ~7 ms/loop from ffmpeg's muxer dropping the final partial frame); or standalone .iamf; or 4/9/16-ch ambiX WAV.
IAMF support: scene-based element, ambisonics mono mode, Opus. OBU trims (incl. 312-sample pre-skip) applied, mix-presentation gains applied. Not yet: projection-mode ambisonics, non-stereo channel beds.
Conventions: +azimuth = left (CCW from front), +elevation = up. Rotator is fed listener orientation: yaw = view yaw, pitch = −view pitch (library +pitch tilts listener down), roll = slider (+ = tilt right). Expected check: place source hard left (+90°), ILD strongly positive; turn view left 90°, ILD → 0.
Build: 173d01a0 · 2026-07-09 (composite md5 of glue+page+worklet+IAMF pipeline sources, first 8 hex — see design-log §13ac; not the module md5).