nx_nv1_lpc.nx

nx_nv1_lpc.nx -- NishiLossless v1 LPC rung: FLAC-class lossless PCM compression INSIDE the NLC1 container (the named next rung in knowledge/specs/2026-06-10-nishilossless-nv1-container.md). New chunk kind 0x4C 'L' = compressed Int16 PCM block. Payload: u8 mode 0..3 = fixed predictor order; 255 = verbatim escape u8 k Rice parameter (0..30; 0 when verbatim) u32 nsamples decoded Int16 sample count (little-endian) mode==255 : nsamples*2 bytes raw LE Int16 mode 0..3 : mode*2 bytes warmup raw LE Int16, then the Rice bitstream (LSB-first within each byte), zero-padded to a byte edge. Fixed predictors (FLAC's fixed mode, exact integer math = zero loss): o0: pred = 0 o1: pred = x[i-1] o2: pred = 2x[i-1] - x[i-2] o3: pred = 3x[i-1] - 3x[i-2] + x[i-3] Residual r = x[i] - pred, zigzag u = (r<0 ? -2r-1 : 2r), Rice(u,k) = (u>>k) one-bits, a zero bit, then the k low bits of u LSB-first. The ENCODER costs every (order, k<16) pair EXACTLY plus the verbatim escape and writes whichever is smallest -- so the payload is NEVER larger than 6 + 2*nsamples (noise degrades to verbatim, not expansion). The DECODER is a validator too: every malformation returns a named negative (tamper-evidence doctrine), including out-of-range reconstruction (-7) so a tampered stream cannot decode silently. Scratch is sys_mmap'd per encode call (no munmap helper exists; the team-side callers are gates and one-shot transcoders). license_tier: ORIGINAL