nx_vcodec_pskip_probe.nx source

1// nx_vcodec_pskip_probe.nx -- SIZE THE P-SKIP GAP (seq1105 rung-1 diagnostic). x264 skips 41.9% of 2// foreman P-MBs; its P-SKIP is a MOTION-COMPENSATED copy at the predicted MV with zero residual. 3// OUR skip is ZERO-MV-only (dosk iff vm_sad_zero <= sad_thresh) -- on panning content it may never 4// fire. This probe replays the SHIPPED P chain (rct9, emode 673) on a y4m and, per P frame, counts 5// against the SAME pre-encode reference the encoder saw: 6// ourskip = MBs with zero-MV SAD <= qp*94 (what the shipped gate can skip today) 7// mcskip = MBs with best-searched SAD <= qp*94 (what an MC-skip/merge mode could skip) 8// The mcskip-ourskip delta is the addressable population of rung-1. license: ORIGINAL 9import "nx_syscalls.nx" 10import "nx_video_codec_wasm.nx" 11 12const SW: i64 = 352 13const SH: i64 = 288 14const NF: i64 = 48 15const KEYMUL: i64 = 188 16const PMUL: i64 = 94 17 18func gw(s: *u8) -> i64 { var n: i64=0; while s[n]!=(0 as u8){n=n+1} sys_write(1,s,n); return 0 } 19func gn(v: i64) -> i64 { 20 let b: *u8=sys_mmap(28); var m: i64=v; if m<0{sys_write(1,"-" as *u8,1);m=0-m} 21 let t: *u8=sys_mmap(28); var k: i64=0; if m==0{t[0]=48 as u8;k=1} while m>0{t[k]=(48+(m%10)) as u8;m=m/10;k=k+1} 22 var i: i64=0; while i<k{b[i]=t[k-1-i];i=i+1} sys_write(1,b,k); return 0 } 23func cpb(d: *u8, s: *u8, n: i64) -> i64 { var i: i64=0; while i<n { d[i]=s[i]; i=i+1 } return 0 } 24 25func frames(yuv: *u8, hi: i64, total: i64, fp: *i64, fdata: i64) -> i64 { 26 var nf: i64=0; var p: i64=hi 27 while nf < NF { if p>=total { break } 28 var q: i64=p; while q<total { if (yuv[q]&0xff)==10 { break } q=q+1 } q=q+1 29 if q+fdata>total { break } fp[nf]=(yuv as i64)+q; nf=nf+1; p=q+fdata } 30 return nf } 31 32func runq(fp: *i64, qp: i64, sz: i64) -> i64 { 33 let prevE: *u8=sys_mmap(sz+64); let reconE: *u8=sys_mmap(sz+64); let ref0: *u8=sys_mmap(sz+64) 34 let wire: *u8=sys_mmap(4194304); let blk: *i64=sys_mmap(512) as *i64; let mv: *i64=sys_mmap(128) as *i64 35 let est: *i64=sys_mmap(64) as *i64; let probs: *i64=sys_mmap(64*8) as *i64; let rcbuf: *u8=sys_mmap(4194304) 36 let t8c: *i64=sys_mmap(8192) as *i64; let rctx: *i64=sys_mmap(128) as *i64 37 let plane: *i64=sys_mmap(65536) as *i64 38 let smv: *i64=sys_mmap(32) as *i64 39 vc_t8_init(t8c) 40 var z: i64=0; while z<sz { prevE[z]=0 as u8; z=z+1 } 41 let BW: i64=SW/16; let BH: i64=SH/16 42 let thr: i64 = qp*PMUL 43 var mbs: i64=0; var ours: i64=0; var mcs: i64=0 44 var zsum: i64=0; var bsum: i64=0 45 var f: i64=0 46 while f < NF { 47 let cur: *u8=fp[f] as *u8 48 rctx[0]=673; rctx[1]=est as i64; rctx[2]=probs as i64; rctx[3]=rcbuf as i64; rctx[4]=t8c as i64 49 rctx[5]=0; rctx[6]=0; rctx[7]=0; rctx[8]=0; rctx[9]=plane as i64 50 if f==0 { 51 vv_enc_rc(cur, prevE, reconE, SW, SH, qp, 1, qp*KEYMUL, wire, 4194304, blk, mv, rctx) 52 } else { 53 cpb(ref0, prevE, sz) // the exact reference the encoder is about to use 54 vv_enc_rct9(cur, prevE, reconE, SW, SH, qp, thr, wire, 4194304, blk, mv, rctx) 55 var by: i64=0 56 while by < BH { var bx: i64=0 57 while bx < BW { 58 let zs: i64 = vm_sad_zero(cur, ref0, SW, bx, by, 16) 59 let bs: i64 = vm_search_q(cur, ref0, SW, SH, bx, by, 16, 16, smv, qp, vmscr3) 60 mbs=mbs+1; zsum=zsum+zs; bsum=bsum+bs 61 if zs <= thr { ours=ours+1 } 62 if bs <= thr { mcs=mcs+1 } 63 bx=bx+1 } by=by+1 } 64 } 65 cpb(prevE, reconE, sz) 66 f=f+1 67 } 68 gw("PSKIP q=" as *u8); gn(qp); gw(" thr=" as *u8); gn(thr) 69 gw(" mbs=" as *u8); gn(mbs) 70 gw(" ourskip_permille=" as *u8); gn(ours*1000/mbs) 71 gw(" mcskip_permille=" as *u8); gn(mcs*1000/mbs) 72 gw(" mean_zsad=" as *u8); gn(zsum/mbs) 73 gw(" mean_bestsad=" as *u8); gn(bsum/mbs) 74 gw("\n" as *u8) 75 return 0 } 76 77func main(argc: i64, argv: *i64) -> i64 { 78 let vmscr3: *i64 = sys_mmap(32) as *i64 // vm_search scratch (2026-07-29: hoisted ONE alloc; the per-call sys_mmap inside vm_search was the wasm 0-stub + native map-leak class) 79 var ypath: *u8 = "/tmp/seq.y4m" as *u8 80 if argc >= 2 { ypath = argv[1] as *u8 } 81 let box: *i64 = sys_mmap(16) as *i64 82 let yuv: *u8 = sys_read_file(ypath, box) 83 if (yuv as i64)==0 { gw("cannot read y4m -> RED\n" as *u8); return 1 } 84 let total: i64=box[0] 85 var hi: i64=0; while hi<total { if (yuv[hi]&0xff)==10 { break } hi=hi+1 } hi=hi+1 86 let C2: i64=(SW/2)*(SH/2); let fdata: i64=SW*SH+2*C2 87 let fp: *i64=sys_mmap(128*8) as *i64 88 let nf: i64=frames(yuv, hi, total, fp, fdata) 89 if nf < NF { gw("too few frames -> RED\n" as *u8); return 1 } 90 runq(fp, 16, fdata) 91 runq(fp, 24, fdata) 92 runq(fp, 32, fdata) 93 gw("PSKIP-PROBE: DONE\n" as *u8) 94 return 0 }