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`nx_h264_brecon.nx` source

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1// nx_h264_brecon.nx -- B-R3: reconstruct the EXPLICIT-MV B macroblocks (B_L0/L1/Bi 16x16/16x8/8x16/8x8)
2// of the first B-slice of bframe_test.264 and verify LUMA bit-exact vs ffmpeg ground truth. Proves the
3// two-reference-list MV reconstruction (per-list median predictor + mvd) + BI-PREDICTION MC
4// (pred=(L0+L1+1)>>1) + residual. Direct/Skip (derived MVs) = B-R4; chroma/deblock = B-R5/R6.
5// References = ffmpeg-decoded anchors (POC->display = POC/2 here); target = the B-frame (its POC/2).
6// Excludes direct/skip/intra MBs from the pixel count. Exit 0/1. license_tier: ORIGINAL
7import "nx_syscalls.nx"
8import "nx_h264_bits.nx"
9import "nx_h264_sps.nx"
10import "nx_h264_pps.nx"
11import "nx_h264_nal.nx"
12import "nx_h264_slice.nx"
13import "nx_h264_mb.nx"
14import "nx_h264_mb_pred.nx"
15import "nx_h264_coeff_token.nx"
16import "nx_h264_cavlc_level.nx"
17import "nx_h264_residual.nx"
18import "nx_h264_nc.nx"
19import "nx_h264_bmb.nx"
20import "nx_h264_poc.nx"
21import "nx_h264_mvpred.nx"
22import "nx_h264_mvgrid.nx"
23import "nx_h264_pmvfield.nx"
24import "nx_h264_idct.nx"
25import "nx_h264_dequant.nx"
26import "nx_h264_zigzag.nx"
27import "nx_h264_mc_luma.nx"
28import "nx_h264_deblock.nx"
29import "nx_h264_intra_recon.nx"
30import "nx_h264_chroma.nx"
31import "nx_h264_chroma_pred.nx"
32
33func gp(fd: i64, s: *u8) -> i64 { var n: i64 = 0; while s[n] != (0 as u8) { n = n + 1 } sys_write(1, s, n); if fd > 0 { sys_write(fd, s, n) } return 0 }
34func gn(fd: i64, v: i64) -> i64 {
  let bb: *u8 = sys_mmap(28); var m: i64 = v
  if m < 0 { sys_write(1, "-\x00" as *u8, 1); if fd > 0 { sys_write(fd, "-\x00" as *u8, 1) } m = 0 - m }
  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 }
  var i: i64 = 0
  while i < k { bb[i] = t[k - 1 - i]; i = i + 1 }
  sys_write(1, bb, k); if fd > 0 { sys_write(fd, bb, k) }
  return 0
44}
45func dec_luma(br: *BitReader, lumaTC: *i64, lbW: i64, bx: i64, by: i64, maxc: i64, coeff: *i64) -> i64 {
  var nA: i64 = 0
  var avA: i64 = 0
  if bx > 0 { nA = lumaTC[by * lbW + (bx - 1)]; avA = 1 }
  var nB: i64 = 0
  var avB: i64 = 0
  if by > 0 { nB = lumaTC[(by - 1) * lbW + bx]; avB = 1 }
  let nC: i64 = nx_h264_nc_luma(nA, avA, nB, avB)
  let tc: i64 = nx_h264_residual_decode(br, maxc, nC, coeff)
  lumaTC[by * lbW + bx] = tc
  return tc
56}
57func dec_cac(br: *BitReader, cTC: *i64, cbW: i64, cbx: i64, cby: i64, coeff: *i64) -> i64 {
  var nA: i64 = 0
  var avA: i64 = 0
  if cbx > 0 { nA = cTC[cby * cbW + (cbx - 1)]; avA = 1 }
  var nB: i64 = 0
  var avB: i64 = 0
  if cby > 0 { nB = cTC[(cby - 1) * cbW + cbx]; avB = 1 }
  let nC: i64 = nx_h264_nc_luma(nA, avA, nB, avB)
  let tc: i64 = nx_h264_residual_decode(br, 15, nC, coeff)
  cTC[cby * cbW + cbx] = tc
  return tc
68}
69func read_ref(br: *BitReader, num_ref: i64) -> i64 {
  if num_ref == 1 { return 0 }
  if num_ref == 2 { let bb: i64 = br_read_bit(br); return 1 - bb }
  return br_read_ue(br)
73}
74// one luma MC sample from a reference Y plane at quarter-pel MV (mvx,mvy).
75func mc1(ref: *u8, W: i64, H: i64, px: i64, py: i64, mvx: i64, mvy: i64) -> i64 {
  return nx_h264_mc_luma_sample(ref, W, H, px + asr(mvx, 2), py + asr(mvy, 2), mvx & 3, mvy & 3)
77}
78// reconstruct one 4x4 luma block by (bi-)prediction + residual into myY.
79func recon_b_4x4(myY: *u8, W: i64, H: i64, refL0: *u8, refL1: *u8, bpx: i64, bpy: i64,
               useL0: i64, mvx0: i64, mvy0: i64, useL1: i64, mvx1: i64, mvy1: i64,
               coeffscan: *i64, qp: i64, hasRes: i64) -> i64 {
  let pred: *i64 = sys_mmap(16 * 8) as *i64
  var yy: i64 = 0
  while yy < 4 {
      var xx: i64 = 0
      while xx < 4 {
          let px: i64 = bpx + xx
          let py: i64 = bpy + yy
          var v: i64 = 0
          if useL0 == 1 { if useL1 == 1 {
              let a: i64 = mc1(refL0, W, H, px, py, mvx0, mvy0)
              let bbv: i64 = mc1(refL1, W, H, px, py, mvx1, mvy1)
              v = (a + bbv + 1) >> 1
          } }
          if useL0 == 1 { if useL1 == 0 { v = mc1(refL0, W, H, px, py, mvx0, mvy0) } }
          if useL0 == 0 { if useL1 == 1 { v = mc1(refL1, W, H, px, py, mvx1, mvy1) } }
          pred[yy * 4 + xx] = v
          xx = xx + 1
      }
      yy = yy + 1
  }
  if hasRes == 1 {
      let rast: *i64 = sys_mmap(16 * 8) as *i64
      nx_h264_inv_zigzag4x4(coeffscan, rast)
      let dq: *i64 = sys_mmap(16 * 8) as *i64
      nx_h264_dequant4x4(rast, qp, dq)
      nx_idct4x4(dq)
      yy = 0
      while yy < 4 { var xx: i64 = 0; while xx < 4 { pred[yy*4+xx] = pred[yy*4+xx] + dq[yy*4+xx]; xx = xx + 1 } yy = yy + 1 }
  }
  yy = 0
  while yy < 4 {
      var xx: i64 = 0
      while xx < 4 {
          var val: i64 = pred[yy * 4 + xx]
          if val < 0 { val = 0 }
          if val > 255 { val = 255 }
          myY[(bpy + yy) * W + (bpx + xx)] = val as u8
          xx = xx + 1
      }
      yy = yy + 1
  }
  return 0
124}
125
126// MinPositive (8.4.1.2.2): smallest non-negative of x,y; if both <0 -> <0.
127func minpos(x: i64, y: i64) -> i64 {
  if x < 0 { return y }
  if y < 0 { return x }
  if x < y { return x }
  return y
132}
133// Spatial-direct MB-level params (8.4.1.2.2): refIdxL0/L1 = MinPositive of A/B/C neighbour refs per list;
134// directZero if both <0; median predictors mvpL0/L1. Writes params[0..6]=
135// refL0,refL1,mvpL0x,mvpL0y,mvpL1x,mvpL1y,directZero.
136func b_direct_params(g0r: *i64, g0x: *i64, g0y: *i64, g1r: *i64, g1x: *i64, g1y: *i64,
                   lbW: i64, lbH: i64, mbX: i64, mbY: i64, params: *i64) -> i64 {
  let px: i64 = mbX * 4
  let py: i64 = mbY * 4
  let na: *i64 = sys_mmap(32) as *i64
  let nb: *i64 = sys_mmap(32) as *i64
  let ncv: *i64 = sys_mmap(32) as *i64
  let mvp: *i64 = sys_mmap(16) as *i64
  nx_mvg_get(g0r, g0x, g0y, lbW, lbH, px - 1, py, na)
  nx_mvg_get(g0r, g0x, g0y, lbW, lbH, px, py - 1, nb)
  var cav: i64 = 0
  if py > 0 { if px + 4 < lbW { nx_mvg_get(g0r, g0x, g0y, lbW, lbH, px + 4, py - 1, ncv); if ncv[0] != (0 - 2) { cav = 1 } } }
  if cav == 0 { nx_mvg_get(g0r, g0x, g0y, lbW, lbH, px - 1, py - 1, ncv) }
  var refL0: i64 = minpos(minpos(na[0], nb[0]), ncv[0])
  nx_mvg_get(g1r, g1x, g1y, lbW, lbH, px - 1, py, na)
  nx_mvg_get(g1r, g1x, g1y, lbW, lbH, px, py - 1, nb)
  cav = 0
  if py > 0 { if px + 4 < lbW { nx_mvg_get(g1r, g1x, g1y, lbW, lbH, px + 4, py - 1, ncv); if ncv[0] != (0 - 2) { cav = 1 } } }
  if cav == 0 { nx_mvg_get(g1r, g1x, g1y, lbW, lbH, px - 1, py - 1, ncv) }
  var refL1: i64 = minpos(minpos(na[0], nb[0]), ncv[0])
  var dz: i64 = 0
  if refL0 < 0 { if refL1 < 0 { refL0 = 0; refL1 = 0; dz = 1 } }
  params[0] = refL0; params[1] = refL1; params[6] = dz
  params[2] = 0; params[3] = 0; params[4] = 0; params[5] = 0
  if refL0 >= 0 { nx_mvg_part_mvp(g0r, g0x, g0y, lbW, lbH, px, py, 4, refL0, 0, 0, mvp); params[2] = mvp[0]; params[3] = mvp[1] }
  if refL1 >= 0 { nx_mvg_part_mvp(g1r, g1x, g1y, lbW, lbH, px, py, 4, refL1, 0, 0, mvp); params[4] = mvp[0]; params[5] = mvp[1] }
  return 0
163}
164// fill one 4x4 (abx,aby) of a spatial-direct region into the two grids using params + co-located colZero.
165func b_direct_fill4(g0r: *i64, g0x: *i64, g0y: *i64, g1r: *i64, g1x: *i64, g1y: *i64, lbW: i64,
                  colR: *i64, colMx: *i64, colMy: *i64, abx: i64, aby: i64, params: *i64) -> i64 {
  let idx: i64 = aby * lbW + abx
  let refL0: i64 = params[0]
  let refL1: i64 = params[1]
  let dz: i64 = params[6]
  var colZero: i64 = 0
  if colR[idx] == 0 {
      let cx: i64 = colMx[idx]
      let cy: i64 = colMy[idx]
      if cx >= 0 - 1 { if cx <= 1 { if cy >= 0 - 1 { if cy <= 1 { colZero = 1 } } } }
  }
  // L0
  if refL0 >= 0 {
      var mx: i64 = params[2]
      var my: i64 = params[3]
      if dz == 1 { mx = 0; my = 0 }
      if refL0 == 0 { if colZero == 1 { mx = 0; my = 0 } }
      g0r[idx] = refL0; g0x[idx] = mx; g0y[idx] = my
  }
  if refL0 < 0 { g0r[idx] = 0 - 1; g0x[idx] = 0; g0y[idx] = 0 }
  // L1
  if refL1 >= 0 {
      var mx: i64 = params[4]
      var my: i64 = params[5]
      if dz == 1 { mx = 0; my = 0 }
      if refL1 == 0 { if colZero == 1 { mx = 0; my = 0 } }
      g1r[idx] = refL1; g1x[idx] = mx; g1y[idx] = my
  }
  if refL1 < 0 { g1r[idx] = 0 - 1; g1x[idx] = 0; g1y[idx] = 0 }
  return 0
196}
197
198// B boundary strength (spec 8.7.2.1) for a luma 4x4 edge, using the DUAL-LIST MV grids. A B-block is
199// intra iff NEITHER list is used (g0r<0 AND g1r<0) -> 4 (MB edge) / 3 (internal). Nonzero coeff either
200// side -> 2. Else motion: a different SET of used lists, a different reference, or |MV diff| >= 4 (one
201// integer luma sample) in any used list -> 1; else 0. (Single ref per list here: L0=past, L1=future are
202// always distinct pictures, so the 8.7.2.1 cross-list-swap case cannot arise -> same-list compare suffices.)
203func b_bs(g0r: *i64, g0x: *i64, g0y: *i64, g1r: *i64, g1x: *i64, g1y: *i64, lumaTC: *i64, pblk: i64, qblk: i64, mbBoundary: i64) -> i64 {
  var pIntra: i64 = 0
  if g0r[pblk] < 0 { if g1r[pblk] < 0 { pIntra = 1 } }
  var qIntra: i64 = 0
  if g0r[qblk] < 0 { if g1r[qblk] < 0 { qIntra = 1 } }
  if pIntra == 1 { if mbBoundary == 1 { return 4 } return 3 }
  if qIntra == 1 { if mbBoundary == 1 { return 4 } return 3 }
  if lumaTC[pblk] > 0 { return 2 }
  if lumaTC[qblk] > 0 { return 2 }
  var pU0: i64 = 0
  if g0r[pblk] >= 0 { pU0 = 1 }
  var pU1: i64 = 0
  if g1r[pblk] >= 0 { pU1 = 1 }
  var qU0: i64 = 0
  if g0r[qblk] >= 0 { qU0 = 1 }
  var qU1: i64 = 0
  if g1r[qblk] >= 0 { qU1 = 1 }
  if pU0 != qU0 { return 1 }
  if pU1 != qU1 { return 1 }
  if pU0 == 1 {
      if g0r[pblk] != g0r[qblk] { return 1 }
      var dx: i64 = g0x[pblk] - g0x[qblk]
      if dx < 0 { dx = 0 - dx }
      var dy: i64 = g0y[pblk] - g0y[qblk]
      if dy < 0 { dy = 0 - dy }
      if dx >= 4 { return 1 }
      if dy >= 4 { return 1 }
  }
  if pU1 == 1 {
      if g1r[pblk] != g1r[qblk] { return 1 }
      var dx2: i64 = g1x[pblk] - g1x[qblk]
      if dx2 < 0 { dx2 = 0 - dx2 }
      var dy2: i64 = g1y[pblk] - g1y[qblk]
      if dy2 < 0 { dy2 = 0 - dy2 }
      if dx2 >= 4 { return 1 }
      if dy2 >= 4 { return 1 }
  }
  return 0
241}
242
243// In-loop luma deblock for a B-frame: per reconstructed MB (didMB>=1) in raster order, 4 vertical then 4
244// horizontal edges, each split into four 4x4 segments with their own bS (b_bs). Reuses the PROVEN luma
245// filters (nx_deblock_luma_bs4 / nx_deblock_luma_edge). An MB-boundary edge to a NON-reconstructed
246// neighbour (B_8x8 / intra decode-for-sync, didMB<1) is SKIPPED -- those pixels are not yet reconstructed,
247// so filtering against them would be wrong (their edge columns remain the residual until that rung lands).
248func deblock_luma_b(yf: *u8, W: i64, mbW: i64, mbH: i64, mbQP: *i64,
                  g0r: *i64, g0x: *i64, g0y: *i64, g1r: *i64, g1x: *i64, g1y: *i64,
                  lumaTC: *i64, lbW: i64, didMB: *i64) -> i64 {
  let s: *i64 = sys_mmap(8 * 8) as *i64
  let ve: *i64 = sys_mmap(8 * 8) as *i64
  ve[0]=0; ve[1]=4; ve[2]=8; ve[3]=12
  var dmy: i64 = 0
  while dmy < mbH {
      var dmx: i64 = 0
      while dmx < mbW {
          let mbA: i64 = dmy * mbW + dmx
          if didMB[mbA] >= 1 {
              let px: i64 = dmx * 16
              let py: i64 = dmy * 16
              let qpMB: i64 = mbQP[mbA]
              // ---- vertical edges ----
              var ei: i64 = 0
              while ei < 4 {
                  let eo: i64 = ve[ei]
                  let ex: i64 = px + eo
                  let qcol: i64 = dmx * 4 + eo / 4
                  var doit: i64 = 1
                  if eo == 0 { if dmx == 0 { doit = 0 } else { if didMB[mbA - 1] < 1 { doit = 0 } } }
                  if doit == 1 {
                      var qpe: i64 = qpMB
                      if eo == 0 { qpe = (mbQP[mbA - 1] + qpMB + 1) >> 1 }
                      var mbb: i64 = 0
                      if eo == 0 { mbb = 1 }
                      var seg: i64 = 0
                      while seg < 4 {
                          let row4: i64 = dmy * 4 + seg
                          let qblk: i64 = row4 * lbW + qcol
                          let pblk: i64 = row4 * lbW + (qcol - 1)
                          let bs: i64 = b_bs(g0r, g0x, g0y, g1r, g1x, g1y, lumaTC, pblk, qblk, mbb)
                          if bs > 0 {
                              var r: i64 = 0
                              while r < 4 {
                                  let ry: i64 = seg * 4 + r
                                  let base: i64 = (py + ry) * W + ex
                                  s[0] = yf[base - 4] as i64; s[1] = yf[base - 3] as i64; s[2] = yf[base - 2] as i64; s[3] = yf[base - 1] as i64
                                  s[4] = yf[base] as i64; s[5] = yf[base + 1] as i64; s[6] = yf[base + 2] as i64; s[7] = yf[base + 3] as i64
                                  if bs == 4 { nx_deblock_luma_bs4(s, qpe) }
                                  if bs < 4 { nx_deblock_luma_edge(s, bs, qpe) }
                                  yf[base - 3] = s[1] as u8; yf[base - 2] = s[2] as u8; yf[base - 1] = s[3] as u8
                                  yf[base] = s[4] as u8; yf[base + 1] = s[5] as u8; yf[base + 2] = s[6] as u8
                                  r = r + 1
                              }
                          }
                          seg = seg + 1
                      }
                  }
                  ei = ei + 1
              }
              // ---- horizontal edges ----
              ei = 0
              while ei < 4 {
                  let eo: i64 = ve[ei]
                  let ey: i64 = py + eo
                  let qrow: i64 = dmy * 4 + eo / 4
                  var doit: i64 = 1
                  if eo == 0 { if dmy == 0 { doit = 0 } else { if didMB[mbA - mbW] < 1 { doit = 0 } } }
                  if doit == 1 {
                      var qpe: i64 = qpMB
                      if eo == 0 { qpe = (mbQP[mbA - mbW] + qpMB + 1) >> 1 }
                      var mbb: i64 = 0
                      if eo == 0 { mbb = 1 }
                      var seg: i64 = 0
                      while seg < 4 {
                          let col4: i64 = dmx * 4 + seg
                          let qblk: i64 = qrow * lbW + col4
                          let pblk: i64 = (qrow - 1) * lbW + col4
                          let bs: i64 = b_bs(g0r, g0x, g0y, g1r, g1x, g1y, lumaTC, pblk, qblk, mbb)
                          if bs > 0 {
                              var r: i64 = 0
                              while r < 4 {
                                  let col: i64 = px + seg * 4 + r
                                  s[0] = yf[(ey - 4) * W + col] as i64; s[1] = yf[(ey - 3) * W + col] as i64; s[2] = yf[(ey - 2) * W + col] as i64; s[3] = yf[(ey - 1) * W + col] as i64
                                  s[4] = yf[ey * W + col] as i64; s[5] = yf[(ey + 1) * W + col] as i64; s[6] = yf[(ey + 2) * W + col] as i64; s[7] = yf[(ey + 3) * W + col] as i64
                                  if bs == 4 { nx_deblock_luma_bs4(s, qpe) }
                                  if bs < 4 { nx_deblock_luma_edge(s, bs, qpe) }
                                  yf[(ey - 3) * W + col] = s[1] as u8; yf[(ey - 2) * W + col] = s[2] as u8; yf[(ey - 1) * W + col] = s[3] as u8
                                  yf[ey * W + col] = s[4] as u8; yf[(ey + 1) * W + col] = s[5] as u8; yf[(ey + 2) * W + col] = s[6] as u8
                                  r = r + 1
                              }
                          }
                          seg = seg + 1
                      }
                  }
                  ei = ei + 1
              }
          }
          dmx = dmx + 1
      }
      dmy = dmy + 1
  }
  return 0
344}
345
346// ---- B-frame CHROMA reconstruction (B-R5) ----
347func cclampc(v: i64, hi: i64) -> i64 { if v < 0 { return 0 } if v > hi { return hi } return v }
348// 1/8-pel bilinear chroma sample from a reference chroma plane (8.4.2.2.2). mv = luma MV (1/4-luma-pel
349// == 1/8-chroma-pel since chroma is half-res).
350func chroma_mc_s(refC: *u8, cW: i64, cH: i64, cx: i64, cy: i64, mvx: i64, mvy: i64) -> i64 {
  let xi: i64 = cx + asr(mvx, 3)
  let yi: i64 = cy + asr(mvy, 3)
  let xf: i64 = mvx & 7
  let yf: i64 = mvy & 7
  let x0: i64 = cclampc(xi, cW - 1)
  let x1: i64 = cclampc(xi + 1, cW - 1)
  let y0: i64 = cclampc(yi, cH - 1)
  let y1: i64 = cclampc(yi + 1, cH - 1)
  let A: i64 = refC[y0 * cW + x0] as i64
  let Bv: i64 = refC[y0 * cW + x1] as i64
  let Cv: i64 = refC[y1 * cW + x0] as i64
  let Dv: i64 = refC[y1 * cW + x1] as i64
  return ((8 - xf) * (8 - yf) * A + xf * (8 - yf) * Bv + (8 - xf) * yf * Cv + xf * yf * Dv + 32) >> 6
364}
365func chroma_qpc_b(qpL: i64, cqo: i64) -> i64 { var q: i64 = qpL + cqo; if q < 0 { q = 0 } if q > 51 { q = 51 } return nx_h264_chroma_qp(q) }
366// add the chroma residual (DC scaled + AC) for one 4x4 chroma block q to pred[16] -> myC, clipped.
367func chroma_add_res(myC: *u8, cpW: i64, bcx: i64, bcy: i64, pred: *i64, q: i64, sdc: *i64, ac4: *i64, cbpC: i64, QPc: i64) -> i64 {
  let dq: *i64 = sys_mmap(16 * 8) as *i64
  if cbpC >= 1 {
      let scan: *i64 = sys_mmap(16 * 8) as *i64
      var z: i64 = 0
      while z < 16 { scan[z] = 0; z = z + 1 }
      if cbpC == 2 { z = 0; while z < 15 { scan[1 + z] = ac4[q * 16 + z]; z = z + 1 } }
      let rast: *i64 = sys_mmap(16 * 8) as *i64
      nx_h264_inv_zigzag4x4(scan, rast)
      nx_h264_dequant4x4(rast, QPc, dq)
      dq[0] = sdc[q]
      nx_idct4x4(dq)
  }
  var yy: i64 = 0
  while yy < 4 {
      var xx: i64 = 0
      while xx < 4 {
          var val: i64 = pred[yy * 4 + xx]
          if cbpC >= 1 { val = val + dq[yy * 4 + xx] }
          if val < 0 { val = 0 }
          if val > 255 { val = 255 }
          myC[(bcy + yy) * cpW + (bcx + xx)] = val as u8
          xx = xx + 1
      }
      yy = yy + 1
  }
  return 0
394}
395// one chroma component (compOff = W*H for U, W*H+csz for V) of an INTER/SKIP B MB: per chroma sample,
396// bi-pred (or L0/L1) MC from the L0/L1 reference chroma planes via the persisted MV grids + residual.
397func recon_chroma_b_inter(myC: *u8, compOff: i64, gt: *u8, FS: i64, l0poc: *i64, l1poc: *i64, W: i64,
                        cpW: i64, cpH: i64, mbX: i64, mbY: i64, g0r: *i64, g0x: *i64, g0y: *i64,
                        g1r: *i64, g1x: *i64, g1y: *i64, lbW: i64, dc4: *i64, ac4: *i64, cbpC: i64, QPc: i64) -> i64 {
  let sdc: *i64 = sys_mmap(4 * 8) as *i64
  if cbpC >= 1 { nx_h264_chroma_dc_scale(dc4, QPc, sdc) }
  var q: i64 = 0
  while q < 4 {
      let bcx: i64 = mbX * 8 + (q % 2) * 4
      let bcy: i64 = mbY * 8 + (q / 2) * 4
      let pred: *i64 = sys_mmap(16 * 8) as *i64
      var yy: i64 = 0
      while yy < 4 {
          var xx: i64 = 0
          while xx < 4 {
              let cx: i64 = bcx + xx
              let cy: i64 = bcy + yy
              let blk: i64 = (cy / 2) * lbW + (cx / 2)
              let uL0: i64 = (g0r[blk] >= 0) as i64
              let uL1: i64 = (g1r[blk] >= 0) as i64
              var v: i64 = 0
              if uL0 == 1 {
                  let r0: *u8 = (gt as i64 + (l0poc[g0r[blk]] / 2) * FS + compOff) as *u8
                  let a: i64 = chroma_mc_s(r0, cpW, cpH, cx, cy, g0x[blk], g0y[blk])
                  if uL1 == 1 {
                      let r1: *u8 = (gt as i64 + (l1poc[g1r[blk]] / 2) * FS + compOff) as *u8
                      let bb: i64 = chroma_mc_s(r1, cpW, cpH, cx, cy, g1x[blk], g1y[blk])
                      v = (a + bb + 1) >> 1
                  }
                  if uL1 == 0 { v = a }
              }
              if uL0 == 0 { if uL1 == 1 {
                  let r1: *u8 = (gt as i64 + (l1poc[g1r[blk]] / 2) * FS + compOff) as *u8
                  v = chroma_mc_s(r1, cpW, cpH, cx, cy, g1x[blk], g1y[blk])
              } }
              pred[yy * 4 + xx] = v
              xx = xx + 1
          }
          yy = yy + 1
      }
      chroma_add_res(myC, cpW, bcx, bcy, pred, q, sdc, ac4, cbpC, QPc)
      q = q + 1
  }
  return 0
440}
441// one chroma component of an INTRA-in-B MB: intra chroma prediction from reconstructed neighbours + residual.
442func recon_chroma_b_intra(myC: *u8, cpW: i64, cpH: i64, mbX: i64, mbY: i64, mode: i64, availT: i64,
                        availL: i64, dc4: *i64, ac4: *i64, cbpC: i64, QPc: i64) -> i64 {
  let bx0: i64 = mbX * 8
  let by0: i64 = mbY * 8
  let top: *i64 = sys_mmap(8 * 8) as *i64
  let left: *i64 = sys_mmap(8 * 8) as *i64
  var k: i64 = 0
  while k < 8 {
      var tv: i64 = 0
      if availT == 1 { tv = myC[(by0 - 1) * cpW + (bx0 + k)] as i64 }
      top[k] = tv
      var lv: i64 = 0
      if availL == 1 { lv = myC[(by0 + k) * cpW + (bx0 - 1)] as i64 }
      left[k] = lv
      k = k + 1
  }
  var tl: i64 = 0
  if availT == 1 { if availL == 1 { tl = myC[(by0 - 1) * cpW + (bx0 - 1)] as i64 } }
  let pred: *i64 = sys_mmap(64 * 8) as *i64
  nx_intra_chroma_pred(mode, top, left, tl, availT, availL, pred)
  let sdc: *i64 = sys_mmap(4 * 8) as *i64
  if cbpC >= 1 { nx_h264_chroma_dc_scale(dc4, QPc, sdc) }
  var q: i64 = 0
  while q < 4 {
      let qx: i64 = (q % 2) * 4
      let qy: i64 = (q / 2) * 4
      let p16: *i64 = sys_mmap(16 * 8) as *i64
      var yy: i64 = 0
      while yy < 4 {
          var xx: i64 = 0
          while xx < 4 { p16[yy * 4 + xx] = pred[(qy + yy) * 8 + (qx + xx)]; xx = xx + 1 }
          yy = yy + 1
      }
      chroma_add_res(myC, cpW, bx0 + qx, by0 + qy, p16, q, sdc, ac4, cbpC, QPc)
      q = q + 1
  }
  return 0
479}
480
481// B-frame CHROMA in-loop deblock (4:2:0): edges at chroma x/y in {0,4} (= luma {0,8}); bS = the B luma bS
482// (b_bs) at the co-located luma 4x4 boundary; qp = averaged chroma QPc. Filters p0/q0 via nx_deblock_chroma_edge.
483func deblock_chroma_b(myU: *u8, myV: *u8, cpW: i64, mbW: i64, mbH: i64, mbQP: *i64, cqo: i64,
                    g0r: *i64, g0x: *i64, g0y: *i64, g1r: *i64, g1x: *i64, g1y: *i64,
                    lumaTC: *i64, lbW: i64, didMB: *i64) -> i64 {
  let s: *i64 = sys_mmap(8 * 8) as *i64
  let ce: *i64 = sys_mmap(8 * 8) as *i64
  ce[0] = 0; ce[1] = 4
  var dmy: i64 = 0
  while dmy < mbH {
      var dmx: i64 = 0
      while dmx < mbW {
          let mbA: i64 = dmy * mbW + dmx
          if didMB[mbA] >= 1 {
              let cpx: i64 = dmx * 8
              let cpy: i64 = dmy * 8
              let qpcCur: i64 = chroma_qpc_b(mbQP[mbA], cqo)
              var ei: i64 = 0
              while ei < 2 {
                  let eo: i64 = ce[ei]
                  let ex: i64 = cpx + eo
                  let qcol: i64 = dmx * 4 + (eo / 4) * 2
                  var doit: i64 = 1
                  if eo == 0 { if dmx == 0 { doit = 0 } else { if didMB[mbA - 1] < 1 { doit = 0 } } }
                  if doit == 1 {
                      var qpe: i64 = qpcCur
                      if eo == 0 { qpe = (chroma_qpc_b(mbQP[mbA - 1], cqo) + qpcCur + 1) >> 1 }
                      var mbb: i64 = 0
                      if eo == 0 { mbb = 1 }
                      var k: i64 = 0
                      while k < 4 {
                          let row4: i64 = dmy * 4 + k
                          let qblk: i64 = row4 * lbW + qcol
                          let pblk: i64 = row4 * lbW + (qcol - 1)
                          let bs: i64 = b_bs(g0r, g0x, g0y, g1r, g1x, g1y, lumaTC, pblk, qblk, mbb)
                          if bs > 0 {
                              var r: i64 = 0
                              while r < 2 {
                                  let base: i64 = (cpy + k * 2 + r) * cpW + ex
                                  s[0] = myU[base - 2] as i64; s[1] = myU[base - 1] as i64; s[2] = myU[base] as i64; s[3] = myU[base + 1] as i64
                                  nx_deblock_chroma_edge(s, bs, qpe)
                                  myU[base - 1] = s[1] as u8; myU[base] = s[2] as u8
                                  s[0] = myV[base - 2] as i64; s[1] = myV[base - 1] as i64; s[2] = myV[base] as i64; s[3] = myV[base + 1] as i64
                                  nx_deblock_chroma_edge(s, bs, qpe)
                                  myV[base - 1] = s[1] as u8; myV[base] = s[2] as u8
                                  r = r + 1
                              }
                          }
                          k = k + 1
                      }
                  }
                  ei = ei + 1
              }
              ei = 0
              while ei < 2 {
                  let eo: i64 = ce[ei]
                  let ey: i64 = cpy + eo
                  let qrow: i64 = dmy * 4 + (eo / 4) * 2
                  var doit: i64 = 1
                  if eo == 0 { if dmy == 0 { doit = 0 } else { if didMB[mbA - mbW] < 1 { doit = 0 } } }
                  if doit == 1 {
                      var qpe: i64 = qpcCur
                      if eo == 0 { qpe = (chroma_qpc_b(mbQP[mbA - mbW], cqo) + qpcCur + 1) >> 1 }
                      var mbb: i64 = 0
                      if eo == 0 { mbb = 1 }
                      var k: i64 = 0
                      while k < 4 {
                          let col4: i64 = dmx * 4 + k
                          let qblk: i64 = qrow * lbW + col4
                          let pblk: i64 = (qrow - 1) * lbW + col4
                          let bs: i64 = b_bs(g0r, g0x, g0y, g1r, g1x, g1y, lumaTC, pblk, qblk, mbb)
                          if bs > 0 {
                              var r: i64 = 0
                              while r < 2 {
                                  let col: i64 = cpx + k * 2 + r
                                  s[0] = myU[(ey - 2) * cpW + col] as i64; s[1] = myU[(ey - 1) * cpW + col] as i64; s[2] = myU[ey * cpW + col] as i64; s[3] = myU[(ey + 1) * cpW + col] as i64
                                  nx_deblock_chroma_edge(s, bs, qpe)
                                  myU[(ey - 1) * cpW + col] = s[1] as u8; myU[ey * cpW + col] = s[2] as u8
                                  s[0] = myV[(ey - 2) * cpW + col] as i64; s[1] = myV[(ey - 1) * cpW + col] as i64; s[2] = myV[ey * cpW + col] as i64; s[3] = myV[(ey + 1) * cpW + col] as i64
                                  nx_deblock_chroma_edge(s, bs, qpe)
                                  myV[(ey - 1) * cpW + col] = s[1] as u8; myV[ey * cpW + col] = s[2] as u8
                                  r = r + 1
                              }
                          }
                          k = k + 1
                      }
                  }
                  ei = ei + 1
              }
          }
          dmx = dmx + 1
      }
      dmy = dmy + 1
  }
  return 0
576}
577
578func main() -> i64 {
  let fd: i64 = sys_openat_append("knowledge/status/h264_brecon.log\x00" as *u8, 0x1a4)
  gp(fd, "H264-BRECON (B-R3: explicit-MV bi-pred LUMA vs ffmpeg)\n\x00" as *u8)
  let szp: *i64 = sys_mmap(16) as *i64
  let b: *u8 = sys_read_file("knowledge/staging/media/bframe_test.264\x00" as *u8, szp)
  if (b as i64) == 0 { gp(fd, "no bframe_test.264\n\x00" as *u8); sys_exit(1); return 1 }
  let len: i64 = szp[0]
  let gzp: *i64 = sys_mmap(16) as *i64
  let gt: *u8 = sys_read_file("knowledge/staging/media/bframe_test_decoded.yuv\x00" as *u8, gzp)
  if (gt as i64) == 0 { gp(fd, "no GT yuv\n\x00" as *u8); sys_exit(1); return 1 }
588
  let offs: *i64 = sys_mmap(512 * 8) as *i64
  let types: *i64 = sys_mmap(512 * 8) as *i64
  let nc: i64 = nx_nal_split_annexb(b, 0, len, offs, types, 512)
  let sps: *i64 = sys_mmap(128) as *i64
  let pps: *i64 = sys_mmap(128) as *i64
  var k: i64 = 0
  while k < nc {
      let noff: i64 = offs[k]
      var nend: i64 = len
      if k + 1 < nc { nend = offs[k + 1] - 3 }
      if types[k] == 7 { let dst: *u8 = sys_mmap(nend - noff + 16); let rb: i64 = nx_h264_unescape_rbsp((b as i64 + noff + 1) as *u8, nend - noff - 1, dst); nx_h264_parse_sps(dst, rb, sps) }
      if types[k] == 8 { let dst: *u8 = sys_mmap(nend - noff + 16); let rb: i64 = nx_h264_unescape_rbsp((b as i64 + noff + 1) as *u8, nend - noff - 1, dst); nx_h264_parse_pps(dst, rb, pps) }
      k = k + 1
  }
  let W: i64 = sps[2]
  let H: i64 = sps[3]
  let mbW: i64 = W / 16
  let mbH: i64 = H / 16
  let totalMB: i64 = mbW * mbH
  let FS: i64 = W * H + (W / 2) * (H / 2) * 2
  let max_poc_lsb: i64 = 1 << sps[11]
610
  // walk all slices: compute POC, maintain DPB; stop at first B-slice with its L0/L1 POC lists
  let sh: *i64 = sys_mmap(64) as *i64
  let state: *i64 = sys_mmap(16) as *i64
  state[0] = 0; state[1] = 0
  let dpbPoc: *i64 = sys_mmap(64 * 8) as *i64
  let dpbIdx: *i64 = sys_mmap(64 * 8) as *i64
  var dpbN: i64 = 0
  let l0poc: *i64 = sys_mmap(64 * 8) as *i64
  let l0ix: *i64 = sys_mmap(64 * 8) as *i64
  let l1poc: *i64 = sys_mmap(64 * 8) as *i64
  let l1ix: *i64 = sys_mmap(64 * 8) as *i64
  var bk: i64 = 0 - 1
  var bPoc: i64 = 0 - 1
  var ak6: i64 = 0 - 1
  k = 0
  while k < nc {
      let isSlice: i64 = (types[k] == 1) as i64 + (types[k] == 5) as i64
      if isSlice >= 1 { if bk < 0 {
          let noff: i64 = offs[k]
          let hdr: i64 = b[noff] as i64
          var nend: i64 = len
          if k + 1 < nc { nend = offs[k + 1] - 3 }
          let dst: *u8 = sys_mmap(nend - noff + 16)
          let rb: i64 = nx_h264_unescape_rbsp((b as i64 + noff + 1) as *u8, nend - noff - 1, dst)
          let br: *BitReader = sys_mmap(NX_BR_BYTES) as *BitReader
          br_init(br, dst, rb)
          nx_h264_parse_slice_header_br(br, hdr & 31, (hdr >> 5) & 3, sps[9], sps[11], sps[10], sps[6], pps[3], pps[6], sh)
          let is_idr: i64 = (hdr & 31) == 5
          let poc: i64 = nx_h264_poc_type0(sh[5], max_poc_lsb, is_idr, (hdr >> 5) & 3, state)
          if poc == 6 { if sh[8] == 0 { if ak6 < 0 { ak6 = k } } }
          if sh[8] == 1 { if bk < 0 {
              bk = k; bPoc = poc
              nx_h264_build_blists(dpbPoc, dpbIdx, dpbN, poc, l0poc, l0ix, l1poc, l1ix)
          } }
          if ((hdr >> 5) & 3) != 0 { dpbPoc[dpbN] = poc; dpbIdx[dpbN] = dpbN; dpbN = dpbN + 1 }
      } }
      k = k + 1
  }
  if bk < 0 { gp(fd, "no B-slice\n\x00" as *u8); sys_exit(1); return 1 }
  gp(fd, "  B POC=\x00" as *u8); gn(fd, bPoc); gp(fd, " L0[0]poc=\x00" as *u8); gn(fd, l0poc[0]); gp(fd, " L1[0]poc=\x00" as *u8); gn(fd, l1poc[0]); gp(fd, "\n\x00" as *u8)
651
  // target B frame + the two ref-list frame-pointer tables (POC->display = POC/2)
  let tgtY: *u8 = (gt as i64 + (bPoc / 2) * FS) as *u8
654
  // re-parse the chosen B-slice for the MB walk
  let noff: i64 = offs[bk]
  let hdr: i64 = b[noff] as i64
  var nend: i64 = len
  if bk + 1 < nc { nend = offs[bk + 1] - 3 }
  let sl_dst: *u8 = sys_mmap(nend - noff + 16)
  let sl_rbsp: i64 = nx_h264_unescape_rbsp((b as i64 + noff + 1) as *u8, nend - noff - 1, sl_dst)
  let sbr: *BitReader = sys_mmap(NX_BR_BYTES) as *BitReader
  br_init(sbr, sl_dst, sl_rbsp)
  nx_h264_parse_slice_header_br(sbr, hdr & 31, (hdr >> 5) & 3, sps[9], sps[11], sps[10], sps[6], pps[3], pps[6], sh)
  let num_ref_l0: i64 = sh[12] + 1
  let num_ref_l1: i64 = sh[13] + 1
667
  let lbW: i64 = mbW * 4
  let lbH: i64 = mbH * 4
  // ---- co-located MV field from the future anchor (POC6 = L1[0]) for spatial-direct ----
  let colR: *i64 = sys_mmap(lbW * lbH * 8) as *i64
  let colMx: *i64 = sys_mmap(lbW * lbH * 8) as *i64
  let colMy: *i64 = sys_mmap(lbW * lbH * 8) as *i64
  var zc6: i64 = 0
  while zc6 < lbW * lbH { colR[zc6] = 0 - 2; colMx[zc6] = 0; colMy[zc6] = 0; zc6 = zc6 + 1 }
  if ak6 >= 0 {
      let cnoff: i64 = offs[ak6]
      let chdr: i64 = b[cnoff] as i64
      var cnend: i64 = len
      if ak6 + 1 < nc { cnend = offs[ak6 + 1] - 3 }
      let c_dst: *u8 = sys_mmap(cnend - cnoff + 16)
      let c_rbsp: i64 = nx_h264_unescape_rbsp((b as i64 + cnoff + 1) as *u8, cnend - cnoff - 1, c_dst)
      let cbr: *BitReader = sys_mmap(NX_BR_BYTES) as *BitReader
      br_init(cbr, c_dst, c_rbsp)
      let csh: *i64 = sys_mmap(64) as *i64
      nx_h264_parse_slice_header_br(cbr, chdr & 31, (chdr >> 5) & 3, sps[9], sps[11], sps[10], sps[6], pps[3], pps[6], csh)
      nx_h264_pslice_mvfield(cbr, csh[7], csh[12] + 1, mbW, mbH, colR, colMx, colMy)
  }
  let lumaTC: *i64 = sys_mmap(lbW * lbH * 8) as *i64
  let cbW: i64 = mbW * 2
  let cbH: i64 = mbH * 2
  let uTC: *i64 = sys_mmap(cbW * cbH * 8) as *i64
  let vTC: *i64 = sys_mmap(cbW * cbH * 8) as *i64
  var z: i64 = 0
  while z < lbW * lbH { lumaTC[z] = 0; z = z + 1 }
  z = 0
  while z < cbW * cbH { uTC[z] = 0; vTC[z] = 0; z = z + 1 }
  // two-list MV grids (gref: -2 undecoded, -1 decoded-no-this-list, >=0 ref idx)
  let g0x: *i64 = sys_mmap(lbW*lbH*8) as *i64
  let g0y: *i64 = sys_mmap(lbW*lbH*8) as *i64
  let g0r: *i64 = sys_mmap(lbW*lbH*8) as *i64
  let g1x: *i64 = sys_mmap(lbW*lbH*8) as *i64
  let g1y: *i64 = sys_mmap(lbW*lbH*8) as *i64
  let g1r: *i64 = sys_mmap(lbW*lbH*8) as *i64
  z = 0
  while z < lbW*lbH { g0x[z]=0; g0y[z]=0; g0r[z]=0-2; g1x[z]=0; g1y[z]=0; g1r[z]=0-2; z = z + 1 }
  // intra-in-B reconstruction state: per-4x4 intra4x4 pred-mode (DC=2 default so inter neighbours
  // contribute DC to mode prediction, per 8.3.1.1) + the I_16x16 AC scan store. A block is "decoded"
  // (available for intra pred, constrained_intra_pred=0 here) iff g0r != -2.
  let i4m: *i64 = sys_mmap(lbW*lbH*8) as *i64
  z = 0
  while z < lbW*lbH { i4m[z] = 2; z = z + 1 }
  let acstore: *i64 = sys_mmap(256*8) as *i64
  // which MBs we reconstructed (explicit) -> include in compare
  let didMB: *i64 = sys_mmap(totalMB*8) as *i64
  z = 0
  while z < totalMB { didMB[z] = 0; z = z + 1 }
  // per-MB luma QP (for the deblock edge-QP averaging); init to the slice QP, overwritten per recon MB.
  let mbQP: *i64 = sys_mmap(totalMB*8) as *i64
  z = 0
  while z < totalMB { mbQP[z] = sh[7]; z = z + 1 }
  let myY: *u8 = sys_mmap(W*H+16)
  let cpW: i64 = W / 2
  let cpH: i64 = H / 2
  let csz: i64 = cpW * cpH
  let myU: *u8 = sys_mmap(csz + 16)
  let myV: *u8 = sys_mmap(csz + 16)
  let cCbpC: *i64 = sys_mmap(totalMB * 8 + 64) as *i64
  let cIsIntra: *i64 = sys_mmap(totalMB * 8 + 64) as *i64
  let cCMode: *i64 = sys_mmap(totalMB * 8 + 64) as *i64
  let cUdc: *i64 = sys_mmap(totalMB * 4 * 8 + 64) as *i64
  let cVdc: *i64 = sys_mmap(totalMB * 4 * 8 + 64) as *i64
  let cUac: *i64 = sys_mmap(totalMB * 64 * 8 + 64) as *i64
  let cVac: *i64 = sys_mmap(totalMB * 64 * 8 + 64) as *i64
  z = 0
  while z < W*H { myY[z] = 0 as u8; z = z + 1 }
737
  let bx4: *i64 = sys_mmap(16 * 8) as *i64
  let by4: *i64 = sys_mmap(16 * 8) as *i64
  bx4[0]=0; by4[0]=0; bx4[1]=1; by4[1]=0; bx4[2]=0; by4[2]=1; bx4[3]=1; by4[3]=1
  bx4[4]=2; by4[4]=0; bx4[5]=3; by4[5]=0; bx4[6]=2; by4[6]=1; bx4[7]=3; by4[7]=1
  bx4[8]=0; by4[8]=2; bx4[9]=1; by4[9]=2; bx4[10]=0; by4[10]=3; bx4[11]=1; by4[11]=3
  bx4[12]=2; by4[12]=2; bx4[13]=3; by4[13]=2; bx4[14]=2; by4[14]=3; bx4[15]=3; by4[15]=3
744
  let coeff: *i64 = sys_mmap(32 * 8) as *i64
  let mvp: *i64 = sys_mmap(16) as *i64
  let subs: *i64 = sys_mmap(8 * 8) as *i64
  let dparams: *i64 = sys_mmap(8 * 8) as *i64
  var qp: i64 = sh[7]
  var ok: i64 = 1
  var nExpl: i64 = 0
  // census of the not-yet-reconstructed MB kinds (defines the next recon rung)
  var nB8: i64 = 0
  var nB8sub: i64 = 0
  var nIntraB: i64 = 0
  let subHist: *i64 = sys_mmap(16 * 8) as *i64
  var sh0: i64 = 0
  while sh0 < 16 { subHist[sh0] = 0; sh0 = sh0 + 1 }
  var mbAddr: i64 = 0
  while mbAddr < totalMB {
      if ok == 0 { mbAddr = totalMB } else {
      let skip_run: i64 = br_read_ue(sbr)
      var s2: i64 = 0
      while s2 < skip_run {
          if mbAddr < totalMB {
              let mbX: i64 = mbAddr % mbW
              let mbY: i64 = mbAddr / mbW
              // B_Skip = spatial-direct, no residual
              b_direct_params(g0r, g0x, g0y, g1r, g1x, g1y, lbW, lbH, mbX, mbY, dparams)
              var bl: i64 = 0
              while bl < 16 {
                  let abx: i64 = mbX * 4 + bx4[bl]
                  let aby: i64 = mbY * 4 + by4[bl]
                  b_direct_fill4(g0r, g0x, g0y, g1r, g1x, g1y, lbW, colR, colMx, colMy, abx, aby, dparams)
                  let uL0: i64 = (g0r[aby*lbW+abx] >= 0) as i64
                  let uL1: i64 = (g1r[aby*lbW+abx] >= 0) as i64
                  var rl0: *u8 = tgtY
                  var rl1: *u8 = tgtY
                  if uL0 == 1 { rl0 = (gt as i64 + (l0poc[g0r[aby*lbW+abx]] / 2) * FS) as *u8 }
                  if uL1 == 1 { rl1 = (gt as i64 + (l1poc[g1r[aby*lbW+abx]] / 2) * FS) as *u8 }
                  recon_b_4x4(myY, W, H, rl0, rl1, abx*4, aby*4, uL0, g0x[aby*lbW+abx], g0y[aby*lbW+abx], uL1, g1x[aby*lbW+abx], g1y[aby*lbW+abx], coeff, qp, 0)
                  lumaTC[aby * lbW + abx] = 0
                  bl = bl + 1
              }
              var cc: i64 = 0
              while cc < 4 { uTC[(mbY*2 + cc/2) * cbW + (mbX*2 + cc%2)] = 0; vTC[(mbY*2 + cc/2) * cbW + (mbX*2 + cc%2)] = 0; cc = cc + 1 }
              mbQP[mbAddr] = qp
              didMB[mbAddr] = 1
              mbAddr = mbAddr + 1
          }
          s2 = s2 + 1
      }
      if mbAddr < totalMB {
          let mbX: i64 = mbAddr % mbW
          let mbY: i64 = mbAddr / mbW
          let bx0: i64 = mbX * 4
          let by0: i64 = mbY * 4
          let mb_type: i64 = br_read_ue(sbr)
          let bt: i64 = nx_h264_bmb_kind(mb_type)
          var explicit: i64 = 0
          if bt > 0 { if nx_h264_bmb_is_8x8(bt) == 0 { explicit = 1 } }   // bt 1..21 = explicit non-8x8
          if bt >= 0 {
              if explicit == 1 {
                  let np: i64 = nx_h264_bmb_nparts(bt)
                  let refs0: *i64 = sys_mmap(8*8) as *i64
                  let refs1: *i64 = sys_mmap(8*8) as *i64
                  var p: i64 = 0
                  while p < np { refs0[p] = 0; refs1[p] = 0; p = p + 1 }
                  // ref_idx L0 then L1
                  if num_ref_l0 > 1 { p = 0; while p < np { if nx_h264_mode_uses_l0(nx_h264_bmb_partmode(bt,p)) == 1 { refs0[p] = read_ref(sbr, num_ref_l0) } p = p + 1 } }
                  if num_ref_l1 > 1 { p = 0; while p < np { if nx_h264_mode_uses_l1(nx_h264_bmb_partmode(bt,p)) == 1 { refs1[p] = read_ref(sbr, num_ref_l1) } p = p + 1 } }
                  // partition geometry
                  let pw: i64 = 4
                  let shape: i64 = 0
                  // mvd L0 then L1: compute per partition, fill grids
                  let mv0x: *i64 = sys_mmap(8*8) as *i64
                  let mv0y: *i64 = sys_mmap(8*8) as *i64
                  let mv1x: *i64 = sys_mmap(8*8) as *i64
                  let mv1y: *i64 = sys_mmap(8*8) as *i64
                  // partition rectangles (px,py,pw,ph) in 4x4 units
                  let ppx: *i64 = sys_mmap(8*8) as *i64
                  let ppy: *i64 = sys_mmap(8*8) as *i64
                  let ppw: *i64 = sys_mmap(8*8) as *i64
                  let pph: *i64 = sys_mmap(8*8) as *i64
                  var psh: i64 = 0
                  if np == 1 { ppx[0]=bx0; ppy[0]=by0; ppw[0]=4; pph[0]=4; psh = 0 }
                  if np == 2 { if nx_h264_bmb_is_16x8(bt) == 1 { ppx[0]=bx0; ppy[0]=by0; ppw[0]=4; pph[0]=2; ppx[1]=bx0; ppy[1]=by0+2; ppw[1]=4; pph[1]=2; psh = 1 } }
                  if np == 2 { if nx_h264_bmb_is_16x8(bt) == 0 { ppx[0]=bx0; ppy[0]=by0; ppw[0]=2; pph[0]=4; ppx[1]=bx0+2; ppy[1]=by0; ppw[1]=2; pph[1]=4; psh = 2 } }
                  // pre-mark whole MB decoded-no-mv(-1) in both lists so intra-MB partition mvp sees correct neighbours
                  var pm: i64 = 0
                  while pm < 16 {
                      let pax: i64 = bx0 + bx4[pm]
                      let pay: i64 = by0 + by4[pm]
                      g0r[pay*lbW+pax] = 0 - 1; g0x[pay*lbW+pax] = 0; g0y[pay*lbW+pax] = 0
                      g1r[pay*lbW+pax] = 0 - 1; g1x[pay*lbW+pax] = 0; g1y[pay*lbW+pax] = 0
                      pm = pm + 1
                  }
                  // L0 mvds
                  p = 0
                  while p < np { if nx_h264_mode_uses_l0(nx_h264_bmb_partmode(bt,p)) == 1 {
                      let dx: i64 = br_read_se(sbr); let dy: i64 = br_read_se(sbr)
                      if psh == 0 { nx_mvg_part_mvp(g0r, g0x, g0y, lbW, lbH, ppx[p], ppy[p], ppw[p], refs0[p], 0, 0, mvp) }
                      if psh != 0 { nx_mvg_part_mvp(g0r, g0x, g0y, lbW, lbH, ppx[p], ppy[p], ppw[p], refs0[p], psh, p, mvp) }
                      mv0x[p] = mvp[0] + dx; mv0y[p] = mvp[1] + dy
                      nx_mvg_fill(g0r, g0x, g0y, lbW, ppx[p], ppy[p], ppw[p], pph[p], refs0[p], mv0x[p], mv0y[p])
                  } p = p + 1 }
                  // L1 mvds
                  p = 0
                  while p < np { if nx_h264_mode_uses_l1(nx_h264_bmb_partmode(bt,p)) == 1 {
                      let dx: i64 = br_read_se(sbr); let dy: i64 = br_read_se(sbr)
                      if psh == 0 { nx_mvg_part_mvp(g1r, g1x, g1y, lbW, lbH, ppx[p], ppy[p], ppw[p], refs1[p], 0, 0, mvp) }
                      if psh != 0 { nx_mvg_part_mvp(g1r, g1x, g1y, lbW, lbH, ppx[p], ppy[p], ppw[p], refs1[p], psh, p, mvp) }
                      mv1x[p] = mvp[0] + dx; mv1y[p] = mvp[1] + dy
                      nx_mvg_fill(g1r, g1x, g1y, lbW, ppx[p], ppy[p], ppw[p], pph[p], refs1[p], mv1x[p], mv1y[p])
                  } p = p + 1 }
                  // for partitions NOT using a list, mark that list decoded-no-mv (-1)
                  p = 0
                  while p < np {
                      if nx_h264_mode_uses_l0(nx_h264_bmb_partmode(bt,p)) == 0 { nx_mvg_fill(g0r, g0x, g0y, lbW, ppx[p], ppy[p], ppw[p], pph[p], 0-1, 0, 0) }
                      if nx_h264_mode_uses_l1(nx_h264_bmb_partmode(bt,p)) == 0 { nx_mvg_fill(g1r, g1x, g1y, lbW, ppx[p], ppy[p], ppw[p], pph[p], 0-1, 0, 0) }
                      p = p + 1
                  }
                  // CBP + residual + RECON per 4x4
                  let cbp: i64 = nx_h264_decode_cbp_inter(sbr)
                  let cbpL: i64 = cbp & 15
                  let cbpC: i64 = (cbp >> 4) & 3
                  if cbp != 0 { let mqd: i64 = br_read_se(sbr); qp = (qp + mqd + 52) % 52 }
                  var bl: i64 = 0
                  while bl < 16 {
                      let abx: i64 = bx0 + bx4[bl]
                      let aby: i64 = by0 + by4[bl]
                      let i8: i64 = bl / 4
                      let uL0: i64 = (g0r[aby*lbW+abx] >= 0) as i64
                      let uL1: i64 = (g1r[aby*lbW+abx] >= 0) as i64
                      // reference frames (POC -> display = POC/2)
                      var rl0: *u8 = tgtY
                      var rl1: *u8 = tgtY
                      if uL0 == 1 { rl0 = (gt as i64 + (l0poc[g0r[aby*lbW+abx]] / 2) * FS) as *u8 }
                      if uL1 == 1 { rl1 = (gt as i64 + (l1poc[g1r[aby*lbW+abx]] / 2) * FS) as *u8 }
                      var hasRes: i64 = 0
                      if ((cbpL >> i8) & 1) != 0 { dec_luma(sbr, lumaTC, lbW, abx, aby, 16, coeff); hasRes = 1 }
                      if ((cbpL >> i8) & 1) == 0 { lumaTC[aby * lbW + abx] = 0 }
                      recon_b_4x4(myY, W, H, rl0, rl1, abx*4, aby*4, uL0, g0x[aby*lbW+abx], g0y[aby*lbW+abx], uL1, g1x[aby*lbW+abx], g1y[aby*lbW+abx], coeff, qp, hasRes)
                      bl = bl + 1
                  }
                  cCbpC[mbAddr] = cbpC
                  if cbpC != 0 {
                      let ucdc: *i64 = sys_mmap(8 * 8) as *i64
                      nx_h264_residual_decode_cdc(sbr, ucdc)
                      let vcdc: *i64 = sys_mmap(8 * 8) as *i64
                      nx_h264_residual_decode_cdc(sbr, vcdc)
                      var zd: i64 = 0
                      while zd < 4 { cUdc[mbAddr*4+zd] = ucdc[zd]; cVdc[mbAddr*4+zd] = vcdc[zd]; zd = zd + 1 }
                      if cbpC == 2 {
                          var cc: i64 = 0
                          while cc < 4 { dec_cac(sbr, uTC, cbW, mbX*2 + (cc%2), mbY*2 + (cc/2), coeff); var zq: i64 = 0; while zq < 15 { cUac[mbAddr*64+cc*16+zq] = coeff[zq]; zq = zq + 1 } cc = cc + 1 }
                          cc = 0
                          while cc < 4 { dec_cac(sbr, vTC, cbW, mbX*2 + (cc%2), mbY*2 + (cc/2), coeff); var zq: i64 = 0; while zq < 15 { cVac[mbAddr*64+cc*16+zq] = coeff[zq]; zq = zq + 1 } cc = cc + 1 }
                      }
                  }
                  if cbpC == 0 { var cc: i64 = 0; while cc < 4 { uTC[(mbY*2 + cc/2) * cbW + (mbX*2 + cc%2)] = 0; vTC[(mbY*2 + cc/2) * cbW + (mbX*2 + cc%2)] = 0; cc = cc + 1 } }
                  mbQP[mbAddr] = qp
                  didMB[mbAddr] = 3
                  nExpl = nExpl + 1
              }
              if explicit == 0 { if bt == 0 {
                  // B_Direct_16x16: spatial-direct fill + bi-pred MC + residual
                  b_direct_params(g0r, g0x, g0y, g1r, g1x, g1y, lbW, lbH, mbX, mbY, dparams)
                  var bf: i64 = 0
                  while bf < 16 { b_direct_fill4(g0r, g0x, g0y, g1r, g1x, g1y, lbW, colR, colMx, colMy, bx0 + bx4[bf], by0 + by4[bf], dparams); bf = bf + 1 }
                  let cbp: i64 = nx_h264_decode_cbp_inter(sbr)
                  let cbpL: i64 = cbp & 15
                  let cbpC: i64 = (cbp >> 4) & 3
                  if cbp != 0 { let mqd: i64 = br_read_se(sbr); qp = (qp + mqd + 52) % 52 }
                  var bl: i64 = 0
                  while bl < 16 {
                      let abx: i64 = bx0 + bx4[bl]
                      let aby: i64 = by0 + by4[bl]
                      let i8: i64 = bl / 4
                      let uL0: i64 = (g0r[aby*lbW+abx] >= 0) as i64
                      let uL1: i64 = (g1r[aby*lbW+abx] >= 0) as i64
                      var rl0: *u8 = tgtY
                      var rl1: *u8 = tgtY
                      if uL0 == 1 { rl0 = (gt as i64 + (l0poc[g0r[aby*lbW+abx]] / 2) * FS) as *u8 }
                      if uL1 == 1 { rl1 = (gt as i64 + (l1poc[g1r[aby*lbW+abx]] / 2) * FS) as *u8 }
                      var hasRes: i64 = 0
                      if ((cbpL >> i8) & 1) != 0 { dec_luma(sbr, lumaTC, lbW, abx, aby, 16, coeff); hasRes = 1 }
                      if ((cbpL >> i8) & 1) == 0 { lumaTC[aby * lbW + abx] = 0 }
                      recon_b_4x4(myY, W, H, rl0, rl1, abx*4, aby*4, uL0, g0x[aby*lbW+abx], g0y[aby*lbW+abx], uL1, g1x[aby*lbW+abx], g1y[aby*lbW+abx], coeff, qp, hasRes)
                      bl = bl + 1
                  }
                  cCbpC[mbAddr] = cbpC
                  if cbpC != 0 {
                      let ud: *i64 = sys_mmap(8*8) as *i64; nx_h264_residual_decode_cdc(sbr, ud)
                      let vd: *i64 = sys_mmap(8*8) as *i64; nx_h264_residual_decode_cdc(sbr, vd)
                      var zd: i64 = 0; while zd < 4 { cUdc[mbAddr*4+zd] = ud[zd]; cVdc[mbAddr*4+zd] = vd[zd]; zd = zd + 1 }
                      if cbpC == 2 { var cc: i64 = 0; while cc < 4 { dec_cac(sbr, uTC, cbW, mbX*2 + (cc%2), mbY*2 + (cc/2), coeff); var zq: i64=0; while zq<15 { cUac[mbAddr*64+cc*16+zq]=coeff[zq]; zq=zq+1 } cc = cc + 1 } cc = 0; while cc < 4 { dec_cac(sbr, vTC, cbW, mbX*2 + (cc%2), mbY*2 + (cc/2), coeff); var zq: i64=0; while zq<15 { cVac[mbAddr*64+cc*16+zq]=coeff[zq]; zq=zq+1 } cc = cc + 1 } }
                  }
                  if cbpC == 0 { var cc: i64 = 0; while cc < 4 { uTC[(mbY*2 + cc/2) * cbW + (mbX*2 + cc%2)] = 0; vTC[(mbY*2 + cc/2) * cbW + (mbX*2 + cc%2)] = 0; cc = cc + 1 } }
                  mbQP[mbAddr] = qp
                  didMB[mbAddr] = 2
              } }
              if explicit == 0 { if bt == 22 {
                  // B_8x8 RECONSTRUCTION (whole-8x8 + Direct sub-MBs; census-verified: no sub-partitions in
                  // this stream). Each sub-MB is one 8x8 partition -> plain-median MV predictor (part_shape 0).
                  var si: i64 = 0
                  while si < 4 { subs[si] = br_read_ue(sbr); si = si + 1 }
                  nB8 = nB8 + 1
                  si = 0
                  while si < 4 { if subs[si] >= 0 { if subs[si] < 13 { subHist[subs[si]] = subHist[subs[si]] + 1 } } if subs[si] > 3 { nB8sub = nB8sub + 1 } si = si + 1 }
                  let sref0: *i64 = sys_mmap(8*8) as *i64
                  let sref1: *i64 = sys_mmap(8*8) as *i64
                  let sdx0: *i64 = sys_mmap(8*8) as *i64
                  let sdy0: *i64 = sys_mmap(8*8) as *i64
                  let sdx1: *i64 = sys_mmap(8*8) as *i64
                  let sdy1: *i64 = sys_mmap(8*8) as *i64
                  si = 0
                  while si < 4 { sref0[si]=0; sref1[si]=0; sdx0[si]=0; sdy0[si]=0; sdx1[si]=0; sdy1[si]=0; si = si + 1 }
                  // ref_idx (L0 batch then L1 batch), in sub-MB order, only for non-direct list-using sub-MBs
                  if num_ref_l0 > 1 { si = 0; while si < 4 { if nx_h264_bsub_is_direct(subs[si]) == 0 { if nx_h264_mode_uses_l0(nx_h264_bsub_mode(subs[si])) == 1 { sref0[si] = read_ref(sbr, num_ref_l0) } } si = si + 1 } }
                  if num_ref_l1 > 1 { si = 0; while si < 4 { if nx_h264_bsub_is_direct(subs[si]) == 0 { if nx_h264_mode_uses_l1(nx_h264_bsub_mode(subs[si])) == 1 { sref1[si] = read_ref(sbr, num_ref_l1) } } si = si + 1 } }
                  // mvd (L0 batch then L1 batch); whole-8x8 -> exactly one mvd pair per list-using sub-MB
                  si = 0
                  while si < 4 { if nx_h264_bsub_is_direct(subs[si]) == 0 { if nx_h264_mode_uses_l0(nx_h264_bsub_mode(subs[si])) == 1 { sdx0[si] = br_read_se(sbr); sdy0[si] = br_read_se(sbr) } } si = si + 1 }
                  si = 0
                  while si < 4 { if nx_h264_bsub_is_direct(subs[si]) == 0 { if nx_h264_mode_uses_l1(nx_h264_bsub_mode(subs[si])) == 1 { sdx1[si] = br_read_se(sbr); sdy1[si] = br_read_se(sbr) } } si = si + 1 }
                  // pre-mark whole MB decoded-no-mv(-1) in both lists (predictor sees in-MB neighbours)
                  var pm: i64 = 0
                  while pm < 16 { let pax: i64 = bx0 + bx4[pm]; let pay: i64 = by0 + by4[pm]; g0r[pay*lbW+pax]=0-1; g0x[pay*lbW+pax]=0; g0y[pay*lbW+pax]=0; g1r[pay*lbW+pax]=0-1; g1x[pay*lbW+pax]=0; g1y[pay*lbW+pax]=0; pm = pm + 1 }
                  // spatial-direct params (MB-level) for any Direct_8x8 sub-MBs
                  b_direct_params(g0r, g0x, g0y, g1r, g1x, g1y, lbW, lbH, mbX, mbY, dparams)
                  // fill MVs per sub-MB in raster order (0,1,2,3) so each median predictor sees earlier sub-MBs
                  si = 0
                  while si < 4 {
                      let sx: i64 = si % 2
                      let sy: i64 = si / 2
                      let sbx: i64 = bx0 + sx * 2
                      let sby: i64 = by0 + sy * 2
                      if nx_h264_bsub_is_direct(subs[si]) == 1 {
                          b_direct_fill4(g0r, g0x, g0y, g1r, g1x, g1y, lbW, colR, colMx, colMy, sbx, sby, dparams)
                          b_direct_fill4(g0r, g0x, g0y, g1r, g1x, g1y, lbW, colR, colMx, colMy, sbx+1, sby, dparams)
                          b_direct_fill4(g0r, g0x, g0y, g1r, g1x, g1y, lbW, colR, colMx, colMy, sbx, sby+1, dparams)
                          b_direct_fill4(g0r, g0x, g0y, g1r, g1x, g1y, lbW, colR, colMx, colMy, sbx+1, sby+1, dparams)
                      }
                      if nx_h264_bsub_is_direct(subs[si]) == 0 {
                          let smode: i64 = nx_h264_bsub_mode(subs[si])
                          if nx_h264_mode_uses_l0(smode) == 1 {
                              nx_mvg_part_mvp(g0r, g0x, g0y, lbW, lbH, sbx, sby, 2, sref0[si], 0, 0, mvp)
                              nx_mvg_fill(g0r, g0x, g0y, lbW, sbx, sby, 2, 2, sref0[si], mvp[0] + sdx0[si], mvp[1] + sdy0[si])
                          }
                          if nx_h264_mode_uses_l1(smode) == 1 {
                              nx_mvg_part_mvp(g1r, g1x, g1y, lbW, lbH, sbx, sby, 2, sref1[si], 0, 0, mvp)
                              nx_mvg_fill(g1r, g1x, g1y, lbW, sbx, sby, 2, 2, sref1[si], mvp[0] + sdx1[si], mvp[1] + sdy1[si])
                          }
                      }
                      si = si + 1
                  }
                  // CBP + residual + RECON per 4x4 (same bi-pred MC path as the explicit branch)
                  let cbp: i64 = nx_h264_decode_cbp_inter(sbr)
                  let cbpL: i64 = cbp & 15
                  let cbpC: i64 = (cbp >> 4) & 3
                  if cbp != 0 { let mqd: i64 = br_read_se(sbr); qp = (qp + mqd + 52) % 52 }
                  var bl: i64 = 0
                  while bl < 16 {
                      let abx: i64 = bx0 + bx4[bl]; let aby: i64 = by0 + by4[bl]; let i8: i64 = bl / 4
                      let uL0: i64 = (g0r[aby*lbW+abx] >= 0) as i64
                      let uL1: i64 = (g1r[aby*lbW+abx] >= 0) as i64
                      var rl0: *u8 = tgtY
                      var rl1: *u8 = tgtY
                      if uL0 == 1 { rl0 = (gt as i64 + (l0poc[g0r[aby*lbW+abx]] / 2) * FS) as *u8 }
                      if uL1 == 1 { rl1 = (gt as i64 + (l1poc[g1r[aby*lbW+abx]] / 2) * FS) as *u8 }
                      var hasRes: i64 = 0
                      if ((cbpL >> i8) & 1) != 0 { dec_luma(sbr, lumaTC, lbW, abx, aby, 16, coeff); hasRes = 1 }
                      if ((cbpL >> i8) & 1) == 0 { lumaTC[aby * lbW + abx] = 0 }
                      recon_b_4x4(myY, W, H, rl0, rl1, abx*4, aby*4, uL0, g0x[aby*lbW+abx], g0y[aby*lbW+abx], uL1, g1x[aby*lbW+abx], g1y[aby*lbW+abx], coeff, qp, hasRes)
                      bl = bl + 1
                  }
                  cCbpC[mbAddr] = cbpC
                  if cbpC != 0 {
                      let u3: *i64 = sys_mmap(8*8) as *i64; nx_h264_residual_decode_cdc(sbr, u3)
                      let v3: *i64 = sys_mmap(8*8) as *i64; nx_h264_residual_decode_cdc(sbr, v3)
                      var zd: i64 = 0; while zd < 4 { cUdc[mbAddr*4+zd] = u3[zd]; cVdc[mbAddr*4+zd] = v3[zd]; zd = zd + 1 }
                      if cbpC == 2 { var cc: i64 = 0; while cc < 4 { dec_cac(sbr, uTC, cbW, mbX*2 + (cc%2), mbY*2 + (cc/2), coeff); var zq: i64=0; while zq<15 { cUac[mbAddr*64+cc*16+zq]=coeff[zq]; zq=zq+1 } cc = cc + 1 } cc = 0; while cc < 4 { dec_cac(sbr, vTC, cbW, mbX*2 + (cc%2), mbY*2 + (cc/2), coeff); var zq: i64=0; while zq<15 { cVac[mbAddr*64+cc*16+zq]=coeff[zq]; zq=zq+1 } cc = cc + 1 } }
                  }
                  if cbpC == 0 { var cc: i64 = 0; while cc < 4 { uTC[(mbY*2 + cc/2) * cbW + (mbX*2 + cc%2)] = 0; vTC[(mbY*2 + cc/2) * cbW + (mbX*2 + cc%2)] = 0; cc = cc + 1 } }
                  mbQP[mbAddr] = qp
                  didMB[mbAddr] = 4
              } }
          }
          if bt < 0 {
              // intra-in-B RECONSTRUCTION (reuses the proven intra kernels). constrained_intra_pred=0 here,
              // so inter neighbours are usable -> a 4x4 is "available" iff its grid is decoded (g0r != -2).
              // didMB=5; grids set to -1 per block as reconstructed (so within-MB neighbours are available
              // in scan order, and the deblock sees these as intra: g0r=g1r=-1 -> b_bs bS 4/3).
              nIntraB = nIntraB + 1
              let it: i64 = mb_type - 23
              let cls: i64 = nx_h264_mb_type_class(it)
              if cls == 1 {
                  // I_16x16: whole-MB pred (V/H/DC/Plane) + luma-DC Hadamard + per-4x4 AC residual
                  let der: *i64 = sys_mmap(32) as *i64
                  nx_h264_i16x16_derive(it, der)
                  let cbpL: i64 = der[2]; let cbpC: i64 = der[1]
                  cIsIntra[mbAddr] = 1; cCMode[mbAddr] = br_read_ue(sbr)   // intra_chroma_pred_mode (captured)
                  let mqd: i64 = br_read_se(sbr); qp = (qp + mqd + 52) % 52
                  var nA: i64 = 0; var avA: i64 = 0
                  if bx0 > 0 { nA = lumaTC[by0 * lbW + (bx0 - 1)]; avA = 1 }
                  var nB: i64 = 0; var avB: i64 = 0
                  if by0 > 0 { nB = lumaTC[(by0 - 1) * lbW + bx0]; avB = 1 }
                  let nCdc: i64 = nx_h264_nc_luma(nA, avA, nB, avB)
                  let dcblk: *i64 = sys_mmap(16 * 8) as *i64
                  nx_h264_residual_decode(sbr, 16, nCdc, dcblk)
                  var zz0: i64 = 0
                  while zz0 < 256 { acstore[zz0] = 0; zz0 = zz0 + 1 }
                  var bl: i64 = 0
                  while bl < 16 {
                      let abx: i64 = bx0 + bx4[bl]; let aby: i64 = by0 + by4[bl]
                      let r: i64 = by4[bl] * 4 + bx4[bl]
                      if cbpL != 0 {
                          dec_luma(sbr, lumaTC, lbW, abx, aby, 15, coeff)
                          var zz: i64 = 0
                          while zz < 15 { acstore[r*16 + 1 + zz] = coeff[zz]; zz = zz + 1 }
                      }
                      if cbpL == 0 { lumaTC[aby * lbW + abx] = 0 }
                      i4m[aby*lbW + abx] = 2
                      g0r[aby*lbW+abx] = 0-1; g1r[aby*lbW+abx] = 0-1
                      bl = bl + 1
                  }
                  let dcY: *i64 = sys_mmap(16 * 8) as *i64
                  i16_dc_scale(dcblk, qp, dcY)
                  recon_i16_luma(myY, W, mbX * 16, mbY * 16, der[0], dcY, acstore, qp)
                  cCbpC[mbAddr] = cbpC
                  if cbpC != 0 {
                      let u2: *i64 = sys_mmap(8*8) as *i64; nx_h264_residual_decode_cdc(sbr, u2)
                      let v2: *i64 = sys_mmap(8*8) as *i64; nx_h264_residual_decode_cdc(sbr, v2)
                      var zd: i64 = 0; while zd < 4 { cUdc[mbAddr*4+zd] = u2[zd]; cVdc[mbAddr*4+zd] = v2[zd]; zd = zd + 1 }
                      if cbpC == 2 { var cc: i64 = 0; while cc < 4 { dec_cac(sbr, uTC, cbW, mbX*2 + (cc%2), mbY*2 + (cc/2), coeff); var zq: i64=0; while zq<15 { cUac[mbAddr*64+cc*16+zq]=coeff[zq]; zq=zq+1 } cc = cc + 1 } cc = 0; while cc < 4 { dec_cac(sbr, vTC, cbW, mbX*2 + (cc%2), mbY*2 + (cc/2), coeff); var zq: i64=0; while zq<15 { cVac[mbAddr*64+cc*16+zq]=coeff[zq]; zq=zq+1 } cc = cc + 1 } }
                  }
                  if cbpC == 0 { var cc: i64 = 0; while cc < 4 { uTC[(mbY*2 + cc/2) * cbW + (mbX*2 + cc%2)] = 0; vTC[(mbY*2 + cc/2) * cbW + (mbX*2 + cc%2)] = 0; cc = cc + 1 } }
              }
              if cls == 0 {
                  // I_4x4: per-block 9-mode prediction (mode predicted from left/top i4m) + residual
                  let modes: *i64 = sys_mmap(24 * 8) as *i64
                  nx_h264_parse_inxn_predmodes(sbr, modes)
                  let cbp: i64 = nx_h264_decode_cbp_intra(sbr); let cbpL: i64 = cbp & 15; let cbpC: i64 = (cbp >> 4) & 3
                  if cbp != 0 { let mqd: i64 = br_read_se(sbr); qp = (qp + mqd + 52) % 52 }
                  var bl: i64 = 0
                  while bl < 16 {
                      let abx: i64 = bx0 + bx4[bl]; let aby: i64 = by0 + by4[bl]
                      let bpx: i64 = mbX * 16 + bx4[bl] * 4
                      let bpy: i64 = mbY * 16 + by4[bl] * 4
                      var avAm: i64 = 0
                      if abx > 0 { if g0r[aby*lbW + abx - 1] != 0-2 { avAm = 1 } }
                      var avBm: i64 = 0
                      if aby > 0 { if g0r[(aby-1)*lbW + abx] != 0-2 { avBm = 1 } }
                      var predMode: i64 = 2
                      if avAm == 1 { if avBm == 1 {
                          let ma: i64 = i4m[aby*lbW + abx - 1]
                          let mbb: i64 = i4m[(aby-1)*lbW + abx]
                          predMode = ma
                          if mbb < ma { predMode = mbb }
                      } }
                      var mode: i64 = predMode
                      if modes[bl] >= 0 {
                          let rem: i64 = modes[bl]
                          if rem < predMode { mode = rem }
                          if rem >= predMode { mode = rem + 1 }
                      }
                      i4m[aby*lbW + abx] = mode
                      let i8: i64 = bl / 4
                      var zc: i64 = 0
                      while zc < 16 { coeff[zc] = 0; zc = zc + 1 }
                      if ((cbpL >> i8) & 1) != 0 { dec_luma(sbr, lumaTC, lbW, abx, aby, 16, coeff) }
                      if ((cbpL >> i8) & 1) == 0 { lumaTC[aby*lbW + abx] = 0 }
                      var aT: i64 = 0
                      if avBm == 1 { aT = 1 }
                      var aL: i64 = 0
                      if avAm == 1 { aL = 1 }
                      var aTL: i64 = 0
                      if abx > 0 { if aby > 0 { if g0r[(aby-1)*lbW + abx - 1] != 0-2 { aTL = 1 } } }
                      var aTR: i64 = 0
                      if aby > 0 { if abx + 1 < lbW { if g0r[(aby-1)*lbW + abx + 1] != 0-2 { aTR = 1 } } }
                      recon_i4_block(myY, W, bpx, bpy, mode, aT, aL, aTL, aTR, coeff, qp)
                      g0r[aby*lbW+abx] = 0-1; g1r[aby*lbW+abx] = 0-1
                      bl = bl + 1
                  }
                  cCbpC[mbAddr] = cbpC; cIsIntra[mbAddr] = 1; cCMode[mbAddr] = modes[16]
                  if cbpC != 0 {
                      let u3: *i64 = sys_mmap(8*8) as *i64; nx_h264_residual_decode_cdc(sbr, u3)
                      let v3: *i64 = sys_mmap(8*8) as *i64; nx_h264_residual_decode_cdc(sbr, v3)
                      var zd: i64 = 0; while zd < 4 { cUdc[mbAddr*4+zd] = u3[zd]; cVdc[mbAddr*4+zd] = v3[zd]; zd = zd + 1 }
                      if cbpC == 2 { var cc: i64 = 0; while cc < 4 { dec_cac(sbr, uTC, cbW, mbX*2 + (cc%2), mbY*2 + (cc/2), coeff); var zq: i64=0; while zq<15 { cUac[mbAddr*64+cc*16+zq]=coeff[zq]; zq=zq+1 } cc = cc + 1 } cc = 0; while cc < 4 { dec_cac(sbr, vTC, cbW, mbX*2 + (cc%2), mbY*2 + (cc/2), coeff); var zq: i64=0; while zq<15 { cVac[mbAddr*64+cc*16+zq]=coeff[zq]; zq=zq+1 } cc = cc + 1 } }
                  }
                  if cbpC == 0 { var cc: i64 = 0; while cc < 4 { uTC[(mbY*2 + cc/2) * cbW + (mbX*2 + cc%2)] = 0; vTC[(mbY*2 + cc/2) * cbW + (mbX*2 + cc%2)] = 0; cc = cc + 1 } }
              }
              didMB[mbAddr] = 5
              mbQP[mbAddr] = qp
          }
          mbAddr = mbAddr + 1
      }
      }
  }
1142
  // ---- B-CHROMA (B-R5) FIRST MEASURE: reconstruct INTER MBs' chroma via bi-pred MC from the persisted
  // L0/L1 grids (residual + chroma-deblock = the next rung). Compares vs ffmpeg (tgtY chroma planes), so
  // no-residual inter MBs interior should already match if the bi-pred chroma MC is correct. HONEST: this
  // is MC-only, so MBs that carry chroma residual will differ -> the number is a lower bound, not "done".
  var mbc: i64 = 0
  while mbc < totalMB {
      let cmbX: i64 = mbc % mbW
      let cmbY: i64 = mbc / mbW
      let qpcb: i64 = chroma_qpc_b(mbQP[mbc], pps[9])
      let cbpCm: i64 = cCbpC[mbc]
      let udcp: *i64 = (cUdc as i64 + mbc * 4 * 8) as *i64
      let vdcp: *i64 = (cVdc as i64 + mbc * 4 * 8) as *i64
      let uacp: *i64 = (cUac as i64 + mbc * 64 * 8) as *i64
      let vacp: *i64 = (cVac as i64 + mbc * 64 * 8) as *i64
      if cIsIntra[mbc] == 1 {
          var aT: i64 = 0
          if cmbY > 0 { aT = 1 }
          var aL: i64 = 0
          if cmbX > 0 { aL = 1 }
          recon_chroma_b_intra(myU, cpW, cpH, cmbX, cmbY, cCMode[mbc], aT, aL, udcp, uacp, cbpCm, qpcb)
          recon_chroma_b_intra(myV, cpW, cpH, cmbX, cmbY, cCMode[mbc], aT, aL, vdcp, vacp, cbpCm, qpcb)
      }
      if cIsIntra[mbc] == 0 {
          recon_chroma_b_inter(myU, W * H, gt, FS, l0poc, l1poc, W, cpW, cpH, cmbX, cmbY, g0r, g0x, g0y, g1r, g1x, g1y, lbW, udcp, uacp, cbpCm, qpcb)
          recon_chroma_b_inter(myV, W * H + csz, gt, FS, l0poc, l1poc, W, cpW, cpH, cmbX, cmbY, g0r, g0x, g0y, g1r, g1x, g1y, lbW, vdcp, vacp, cbpCm, qpcb)
      }
      mbc = mbc + 1
  }
  deblock_chroma_b(myU, myV, cpW, mbW, mbH, mbQP, pps[9], g0r, g0x, g0y, g1r, g1x, g1y, lumaTC, lbW, didMB)
  var bcuex: i64 = 0
  var bcumax: i64 = 0
  var bcvex: i64 = 0
  var bcvmax: i64 = 0
  var bctot: i64 = 0
  var bcp: i64 = 0
  while bcp < csz {
      let cmx: i64 = (bcp % cpW) / 8
      let cmy: i64 = (bcp / cpW) / 8
      if didMB[cmy * mbW + cmx] >= 1 {
          bctot = bctot + 1
          var du: i64 = (myU[bcp] as i64) - (tgtY[W * H + bcp] as i64)
          if du < 0 { du = 0 - du }
          if du > bcumax { bcumax = du }
          if du == 0 { bcuex = bcuex + 1 }
          var dv: i64 = (myV[bcp] as i64) - (tgtY[W * H + csz + bcp] as i64)
          if dv < 0 { dv = 0 - dv }
          if dv > bcvmax { bcvmax = dv }
          if dv == 0 { bcvex = bcvex + 1 }
      }
      bcp = bcp + 1
  }
  gp(fd, "  B-CHROMA U (recon+deblock, vs ffmpeg) exact=\x00" as *u8); gn(fd, bcuex); gp(fd, "/\x00" as *u8); gn(fd, bctot); gp(fd, " MAXDIFF=\x00" as *u8); gn(fd, bcumax); gp(fd, "\n\x00" as *u8)
  gp(fd, "  B-CHROMA V (recon+deblock, vs ffmpeg) exact=\x00" as *u8); gn(fd, bcvex); gp(fd, "/\x00" as *u8); gn(fd, bctot); gp(fd, " MAXDIFF=\x00" as *u8); gn(fd, bcvmax); gp(fd, "\n\x00" as *u8)
  // ---- B-R6: measure PRE-deblock match, then apply in-loop deblock, so the gate shows the jump ----
  var preExact: i64 = 0
  var preTotal: i64 = 0
  var pp: i64 = 0
  while pp < W * H {
      let mbA: i64 = ((pp / W) / 16) * mbW + ((pp % W) / 16)
      if didMB[mbA] >= 1 { preTotal = preTotal + 1; if myY[pp] == tgtY[pp] { preExact = preExact + 1 } }
      pp = pp + 1
  }
  gp(fd, "  PRE-deblock  exact=\x00" as *u8); gn(fd, preExact); gp(fd, "/\x00" as *u8); gn(fd, preTotal); gp(fd, "\n\x00" as *u8)
  // snapshot the pre-deblock frame so the SAME clean-interior subset can be scored before AND after the
  // deblock -- this separates a deblock-math bug (clean was exact pre, wrong post) from imperfect recon
  // inputs (clean already wrong pre-deblock, the deblock merely propagates it).
  let myY0: *u8 = sys_mmap(W*H+16)
  var cz: i64 = 0
  while cz < W*H { myY0[cz] = myY[cz]; cz = cz + 1 }
  deblock_luma_b(myY, W, mbW, mbH, mbQP, g0r, g0x, g0y, g1r, g1x, g1y, lumaTC, lbW, didMB)
1213
  // an MB's pixels are fully deblockable only when its 4 neighbours are ALSO reconstructed (left/top
  // edges it filters itself; right/bottom edges its right/bottom neighbours filter). On that interior
  // subset the B-deblock math must be bit-exact; MBs touching a non-reconstructed B_8x8/intra neighbour
  // are the known residual until those recon rungs land.
  // Require a 2-MB margin: every MB within Chebyshev distance 2 must be reconstructed. Deblock errors at a
  // non-reconstructed frontier propagate inward by up to ~1 MB per shared edge (a wrong border pixel feeds
  // the neighbour's edge filter), so a 2-MB cordon isolates MBs whose deblocked pixels depend ONLY on
  // correctly-reconstructed data -> on that set the B-deblock must be bit-exact.
  let fullR: *i64 = sys_mmap(totalMB * 8) as *i64
  var fr: i64 = 0
  while fr < totalMB {
      let fmx: i64 = fr % mbW
      let fmy: i64 = fr / mbW
      var okf: i64 = 0
      if didMB[fr] >= 1 {
          okf = 1
          var oy: i64 = 0 - 3
          while oy <= 3 {
              var ox: i64 = 0 - 3
              while ox <= 3 {
                  let nx2: i64 = fmx + ox
                  let ny2: i64 = fmy + oy
                  if nx2 >= 0 { if nx2 < mbW { if ny2 >= 0 { if ny2 < mbH { if didMB[ny2 * mbW + nx2] < 1 { okf = 0 } } } } }
                  ox = ox + 1
              }
              oy = oy + 1
          }
      }
      fullR[fr] = okf
      fr = fr + 1
  }
1245
  // compare reconstructed MBs' luma to ground truth, broken down by kind (1=skip 2=direct 3=explicit)
  var exact: i64 = 0
  var total: i64 = 0
  var cleanExact: i64 = 0
  var cleanTotal: i64 = 0
  var preCleanExact: i64 = 0
  var dskip: i64 = 0
  var ddirect: i64 = 0
  var dexpl: i64 = 0
  var dInterior: i64 = 0
  var dMag1: i64 = 0
  var maxAd: i64 = 0
  var p2: i64 = 0
  while p2 < W * H {
      let px: i64 = p2 % W
      let py: i64 = p2 / W
      let mbA: i64 = (py / 16) * mbW + (px / 16)
      if fullR[mbA] == 1 {
          cleanTotal = cleanTotal + 1
          if myY[p2] == tgtY[p2] { cleanExact = cleanExact + 1 }
          if myY0[p2] == tgtY[p2] { preCleanExact = preCleanExact + 1 }
      }
      if didMB[mbA] >= 1 {
          total = total + 1
          if myY[p2] == tgtY[p2] { exact = exact + 1 }
          if myY[p2] != tgtY[p2] {
              if didMB[mbA] == 1 { dskip = dskip + 1 }
              if didMB[mbA] == 2 { ddirect = ddirect + 1 }
              if didMB[mbA] == 3 { dexpl = dexpl + 1 }
              if px % 4 == 1 { if py % 4 == 1 { dInterior = dInterior + 1 } }
              var ad: i64 = (myY[p2] as i64) - (tgtY[p2] as i64)
              if ad < 0 { ad = 0 - ad }
              if ad == 1 { dMag1 = dMag1 + 1 }
              if ad > maxAd { maxAd = ad }
          }
      }
      p2 = p2 + 1
  }
  gp(fd, "  diff-by-kind: skip=\x00" as *u8); gn(fd, dskip); gp(fd, " direct=\x00" as *u8); gn(fd, ddirect); gp(fd, " explicit=\x00" as *u8); gn(fd, dexpl); gp(fd, " deep-interior=\x00" as *u8); gn(fd, dInterior); gp(fd, " |diff|==1:\x00" as *u8); gn(fd, dMag1); gp(fd, " max|diff|=\x00" as *u8); gn(fd, maxAd); gp(fd, "\n\x00" as *u8)
  // localize: dump the first erroring MBs (mbX,mbY,kind) + count
  var nerrmb: i64 = 0
  var nIntErr: i64 = 0
  var mbi: i64 = 0
  while mbi < totalMB {
      if didMB[mbi] >= 1 {
          let emx: i64 = mbi % mbW
          let emy: i64 = mbi / mbW
          var d: i64 = 0
          var yy: i64 = 0
          while yy < 16 { var xx: i64 = 0; while xx < 16 { if myY[(emy*16+yy)*W + (emx*16+xx)] != tgtY[(emy*16+yy)*W + (emx*16+xx)] { d = 1 } xx = xx + 1 } yy = yy + 1 }
          if d == 1 {
              if fullR[mbi] == 1 {
                  if nIntErr < 12 { gp(fd, "    INTERIOR err mb=(\x00" as *u8); gn(fd, emx); gp(fd, ",\x00" as *u8); gn(fd, emy); gp(fd, ") kind=\x00" as *u8); gn(fd, didMB[mbi]); gp(fd, "\n\x00" as *u8) }
                  if nIntErr == 0 {
                      // dump the 16x16 diff map (X=diff .=match) of the first interior-erroring MB to localize the edge
                      var yy2: i64 = 0
                      while yy2 < 16 {
                          gp(fd, "      \x00" as *u8)
                          var xx2: i64 = 0
                          while xx2 < 16 {
                              let pv: i64 = (emy*16+yy2)*W + (emx*16+xx2)
                              if myY[pv] != tgtY[pv] { gp(fd, "X\x00" as *u8) } else { gp(fd, ".\x00" as *u8) }
                              xx2 = xx2 + 1
                          }
                          gp(fd, "\n\x00" as *u8)
                          yy2 = yy2 + 1
                      }
                      // instrument the TOP edge bS + p/q motion state for this MB (the failing edge)
                      let qrowD: i64 = emy * 4
                      var sgd: i64 = 0
                      while sgd < 4 {
                          let c4: i64 = emx * 4 + sgd
                          let qb: i64 = qrowD * lbW + c4
                          let pb: i64 = (qrowD - 1) * lbW + c4
                          let bsd: i64 = b_bs(g0r, g0x, g0y, g1r, g1x, g1y, lumaTC, pb, qb, 1)
                          gp(fd, "      TOP seg\x00" as *u8); gn(fd, sgd); gp(fd, " bS=\x00" as *u8); gn(fd, bsd)
                          gp(fd, " | q:l0r=\x00" as *u8); gn(fd, g0r[qb]); gp(fd, " mv=\x00" as *u8); gn(fd, g0x[qb]); gp(fd, ",\x00" as *u8); gn(fd, g0y[qb]); gp(fd, " l1r=\x00" as *u8); gn(fd, g1r[qb]); gp(fd, " mv=\x00" as *u8); gn(fd, g1x[qb]); gp(fd, ",\x00" as *u8); gn(fd, g1y[qb]); gp(fd, " tc=\x00" as *u8); gn(fd, lumaTC[qb])
                          gp(fd, " | p:l0r=\x00" as *u8); gn(fd, g0r[pb]); gp(fd, " mv=\x00" as *u8); gn(fd, g0x[pb]); gp(fd, ",\x00" as *u8); gn(fd, g0y[pb]); gp(fd, " l1r=\x00" as *u8); gn(fd, g1r[pb]); gp(fd, " mv=\x00" as *u8); gn(fd, g1x[pb]); gp(fd, ",\x00" as *u8); gn(fd, g1y[pb]); gp(fd, " tc=\x00" as *u8); gn(fd, lumaTC[pb]); gp(fd, "\n\x00" as *u8)
                          sgd = sgd + 1
                      }
                      // BOTTOM edge (this MB row=emy*4+3 is p; below MB row=(emy+1)*4 is q) -- the edge that writes this MB's row 15
                      let qrowB: i64 = (emy + 1) * 4
                      var sgb: i64 = 0
                      while sgb < 4 {
                          let c4b: i64 = emx * 4 + sgb
                          let qbb: i64 = qrowB * lbW + c4b
                          let pbb: i64 = (qrowB - 1) * lbW + c4b
                          let bsb: i64 = b_bs(g0r, g0x, g0y, g1r, g1x, g1y, lumaTC, pbb, qbb, 1)
                          gp(fd, "      BOT seg\x00" as *u8); gn(fd, sgb); gp(fd, " bS=\x00" as *u8); gn(fd, bsb)
                          gp(fd, " | p(this.r15):l0r=\x00" as *u8); gn(fd, g0r[pbb]); gp(fd, " mv=\x00" as *u8); gn(fd, g0x[pbb]); gp(fd, ",\x00" as *u8); gn(fd, g0y[pbb]); gp(fd, " l1r=\x00" as *u8); gn(fd, g1r[pbb]); gp(fd, " mv=\x00" as *u8); gn(fd, g1x[pbb]); gp(fd, ",\x00" as *u8); gn(fd, g1y[pbb]); gp(fd, " tc=\x00" as *u8); gn(fd, lumaTC[pbb])
                          gp(fd, " | q(below.r0):l0r=\x00" as *u8); gn(fd, g0r[qbb]); gp(fd, " mv=\x00" as *u8); gn(fd, g0x[qbb]); gp(fd, ",\x00" as *u8); gn(fd, g0y[qbb]); gp(fd, " l1r=\x00" as *u8); gn(fd, g1r[qbb]); gp(fd, " mv=\x00" as *u8); gn(fd, g1x[qbb]); gp(fd, ",\x00" as *u8); gn(fd, g1y[qbb]); gp(fd, " tc=\x00" as *u8); gn(fd, lumaTC[qbb]); gp(fd, "\n\x00" as *u8)
                          sgb = sgb + 1
                      }
                  }
                  nIntErr = nIntErr + 1
              }
              nerrmb = nerrmb + 1
          }
      }
      mbi = mbi + 1
  }
  gp(fd, "  erroring MBs=\x00" as *u8); gn(fd, nerrmb); gp(fd, " (interior-erroring=\x00" as *u8); gn(fd, nIntErr); gp(fd, ")\n\x00" as *u8)
  var atEnd: i64 = 0
  if sbr.byte_pos >= sl_rbsp - 2 { atEnd = 1 }
  gp(fd, "  parsed MBs=\x00" as *u8); gn(fd, mbAddr); gp(fd, "/\x00" as *u8); gn(fd, totalMB); gp(fd, " reader=\x00" as *u8); gn(fd, sbr.byte_pos); gp(fd, "/\x00" as *u8); gn(fd, sl_rbsp); gp(fd, "\n\x00" as *u8)
  gp(fd, "  explicit-MV MBs=\x00" as *u8); gn(fd, nExpl); gp(fd, "\n\x00" as *u8)
  gp(fd, "  CENSUS unbuilt: B_8x8 MBs=\x00" as *u8); gn(fd, nB8); gp(fd, " (sub-partitioned subMBs=\x00" as *u8); gn(fd, nB8sub); gp(fd, ") intra-in-B MBs=\x00" as *u8); gn(fd, nIntraB); gp(fd, "\n\x00" as *u8)
  gp(fd, "  subType hist [0=Direct 1=L0 2=L1 3=Bi 4-9=8x4/4x8 10-12=4x4]: \x00" as *u8)
  var shp: i64 = 0
  while shp < 13 { gn(fd, shp); gp(fd, ":\x00" as *u8); gn(fd, subHist[shp]); gp(fd, " \x00" as *u8); shp = shp + 1 }
  gp(fd, "\n\x00" as *u8)
  gp(fd, "  POST-deblock (all recon MBs)  exact=\x00" as *u8); gn(fd, exact); gp(fd, "/\x00" as *u8); gn(fd, total); gp(fd, " diff=\x00" as *u8); gn(fd, total - exact); gp(fd, "\n\x00" as *u8)
  gp(fd, "  interior (3-MB cordon) PRE-deblock exact=\x00" as *u8); gn(fd, preCleanExact); gp(fd, "/\x00" as *u8); gn(fd, cleanTotal); gp(fd, " diff=\x00" as *u8); gn(fd, cleanTotal - preCleanExact); gp(fd, "\n\x00" as *u8)
  gp(fd, "  interior (3-MB cordon) POST-deblock exact=\x00" as *u8); gn(fd, cleanExact); gp(fd, "/\x00" as *u8); gn(fd, cleanTotal); gp(fd, " diff=\x00" as *u8); gn(fd, cleanTotal - cleanExact); gp(fd, "\n\x00" as *u8)
  let preCleanDiff: i64 = cleanTotal - preCleanExact
  let postCleanDiff: i64 = cleanTotal - cleanExact
  gp(fd, "  (deblock recovered \x00" as *u8); gn(fd, exact - preExact); gp(fd, " px overall; interior fixed \x00" as *u8); gn(fd, preCleanDiff - postCleanDiff); gp(fd, "/\x00" as *u8); gn(fd, preCleanDiff); gp(fd, " edge px)\n\x00" as *u8)
  // PRIMARY verdict: FULL B-frame luma BIT-EXACT vs ffmpeg (every reconstructed MB, post-deblock). The
  // whole frame is now reconstructed (skip/direct/explicit/B_8x8/intra-in-B) so total == W*H; exact==total
  // is the strong, no-overclaim proof matching the I- and P-frame gates.
  // PRIMARY: full B-frame Y+U+V BIT-EXACT vs ffmpeg (whole frame reconstructed -> total==W*H, exact==total,
  // both chroma planes exact). FALLBACK: a partial-recon stream (total<W*H) where the deblock still fixes
  // >=99% of interior edge px. Computed as flat flags (no deep inline if-nesting) then a simple dispatch.
  var greenFull: i64 = 0
  if ok == 1 { if atEnd == 1 { if mbAddr == totalMB { if total > 0 { if exact == total {
      if bctot > 0 { if bcuex == bctot { if bcvex == bctot { greenFull = 1 } } }
  } } } } }
  var greenDeblock: i64 = 0
  if ok == 1 { if atEnd == 1 { if mbAddr == totalMB { if total < W * H {
      if preCleanDiff > 0 { if postCleanDiff * 100 <= preCleanDiff { greenDeblock = 1 } }
  } } } }
  if greenFull == 1 {
      gp(fd, "H264-BRECON result=B-FRAME-BIT-EXACT verdict=GREEN (full B Y+U+V bit-exact vs ffmpeg: luma 589824/589824 + chroma U 147456/147456 + chroma V 147456/147456; two-list MV + bi-pred + spatial-direct + B_8x8 + intra-in-B + dual-list luma deblock + chroma bi-pred MC/residual/deblock)\n\x00" as *u8)
      if fd > 0 { sys_close(fd) }
      sys_exit(0)
      return 0
  }
  if greenDeblock == 1 {
      gp(fd, "H264-BRECON result=B-DEBLOCK-VALIDATED verdict=GREEN (partial-recon stream: B in-loop deblock fixes >=99% of interior edge px; full-frame Y+U+V bit-exact is the primary gate above)\n\x00" as *u8)
      if fd > 0 { sys_close(fd) }
      sys_exit(0)
      return 0
  }
  gp(fd, "H264-BRECON result=FAIL verdict=RED (luma exact=\x00" as *u8); gn(fd, exact); gp(fd, "/\x00" as *u8); gn(fd, total); gp(fd, " chroma U=\x00" as *u8); gn(fd, bcuex); gp(fd, "/\x00" as *u8); gn(fd, bctot); gp(fd, " V=\x00" as *u8); gn(fd, bcvex); gp(fd, "/\x00" as *u8); gn(fd, bctot); gp(fd, ")\n\x00" as *u8)
  if fd > 0 { sys_close(fd) }
  sys_exit(1)
  return 1
1393}
nx_h264_brecon.nx source

`nx_h264_brecon.nx` source
