nx_birdsynth.nx

nx_birdsynth.nx -- SOVEREIGN BAND-LIMITED BIRD-CALL EMITTER (the SKU-2 signal source). Operator: a remote-controlled toy that emits "exact replicas of bird noises based on bird calls". The estate already owns the RULER for that claim -- nx_bioacoustic_bench scores animal-vocalisation realism on ten axes to a per-mille. What it did not own was anything to MEASURE: the only wavs in the corpus are nx_gamemusic.wav and sfx_demo.wav. ★A RULER WITH NOTHING TO MEASURE IS A COMMENT. This organ closes that loop -- emit, measure, iterate -- and the same PCM it writes is what the toy's DAC will eventually clock out. WHY SYNTHESIS AND NOT A SAMPLE. A recording, looped, fails the bench on the axis that matters most: `nonrep`. Real animals never repeat exactly (breath-driven micro-variation), and a dog's habituation is driven precisely by detecting the repeat. So the emitter is GENERATIVE -- per-syllable phase jitter from an LCG means no two utterances are sample-identical -- which is a property a sample player structurally cannot have. ★★BAND-LIMITED ON PURPOSE, AND THAT IS THE WHOLE EXPERIMENT. A harmonic is synthesised ONLY while k*f0 < rate/2. That is correct DSP (no aliasing), and it makes the frequency-cutoff thesis MEASURABLE instead of asserted: render the SAME call at 96 kHz and at 22.05 kHz and the low-rate render cannot carry the upper partials AT ALL -- not "quieter", ABSENT. The bench's ax_ultra / ax_band axes then report that difference as a number. Consumer audio does not fail a dog by being low quality; it fails by being structurally incapable of representing the signal. INTEGER-ONLY (sovereign no-float law). Sine comes from a 65-entry quarter-wave table filled at runtime and mirrored into four quadrants. The table is mmap'd and filled by assignment, NEVER a module-level const array -- a const array here compiles clean and then reads garbage (banked gotcha), and a BSS [N]i64 silently crashes a handler module on startup. usage: nx_birdsynth <out.wav> <rate_hz> <ms> [seed] license_tier: ORIGINAL No hw writes (Rule 26). expect_exit: 0