From 252aa713d40dd54b18c213ffa811745b18fe4235 Mon Sep 17 00:00:00 2001
From: Zac Gaetano <Zgaetano@wilddragon.net>
Date: Mon, 1 Jun 2026 09:07:28 -0400
Subject: [PATCH] fix(capture): drop dur-patch; rdd9 self-maintains growing
 Duration

On-node empirical testing of this bmx v1.6 build showed that raw2bmx's
rdd9 writer with --part already maintains a live, correct header Duration
as the file grows: ffprobe reads a growing duration mid-write (e.g. 2.04s
of a 10s clip while still recording), and the structural-metadata
Duration fields (tags 02020008 / 30020008) hold the real frame count
(0x33 = 51), not -1.

The dur-patch.py added in the previous commit searched the header for
Duration=-1 (0xFF*8) and found 0 fields on rdd9 ("[dur-patch] 0 Duration
fields"), so it was a no-op. Worse, opening the MXF r+b to patch it while
raw2bmx appends over CIFS is a concurrency hazard. Remove it entirely and
rely on raw2bmx's native growing Duration. rdd9 + --index-follows remains
the Premiere-recommended growing flavour (Sony XDCAM essence, index in the
essence partition).

Verified on-node (ffprobe/byte-probe). Live edit-while-record in Premiere
itself still requires user confirmation.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
---
 services/capture/dur-patch.py           | 67 -------------------------
 services/capture/src/capture-manager.js | 14 +++---
 2 files changed, 7 insertions(+), 74 deletions(-)
 delete mode 100644 services/capture/dur-patch.py

diff --git a/services/capture/dur-patch.py b/services/capture/dur-patch.py
deleted file mode 100644
index cec7cf0..0000000
--- a/services/capture/dur-patch.py
+++ /dev/null
@@ -1,67 +0,0 @@
-import sys,time,struct,os
-BODY=bytes([6,14,43,52,2,5,1,1,13,1,2,1,1,3])
-ITS=bytes([6,14,43,52,2,83,1,1,13,1,2,1,1,16,1,0])
-def get_frames(p):
-  try:
-    sz=os.path.getsize(p)
-    if sz<50000:return 0
-    with open(p,"rb") as f:
-      f.seek(max(0,sz-3000000));d=f.read()
-    pos=len(d)
-    while True:
-      i=d.rfind(BODY,0,pos)
-      if i<0:break
-      pos=i;bs=i+16;b0=d[bs]
-      if b0==0x83:bl,bv=4,struct.unpack(">I",b"\x00"+d[bs+1:bs+4])[0]
-      elif b0==0x82:bl,bv=3,struct.unpack(">H",d[bs+1:bs+3])[0]
-      else:bl,bv=1,b0
-      if len(d)<bs+bl+48:break
-      ibc=struct.unpack(">Q",d[bs+bl+40:bs+bl+48])[0]
-      if not ibc:continue
-      itd=d[i+16+bl+bv:i+16+bl+bv+ibc]
-      ii=itd.find(ITS)
-      if ii<0:break
-      ib0=itd[ii+16]
-      if ib0==0x83:ivl,ivv=4,struct.unpack(">I",b"\x00"+itd[ii+17:ii+20])[0]
-      elif ib0==0x82:ivl,ivv=3,struct.unpack(">H",itd[ii+17:ii+19])[0]
-      else:ivl,ivv=1,ib0
-      sd=itd[ii+16+ivl:ii+16+ivl+ivv];p2=isp=dur=0
-      while p2<len(sd)-3:
-        t=struct.unpack(">H",sd[p2:p2+2])[0];l=struct.unpack(">H",sd[p2+2:p2+4])[0]
-        if p2+4+l>len(sd):break
-        v=sd[p2+4:p2+4+l]
-        if t==0x3F0C and l==8:isp=struct.unpack(">q",v)[0]
-        elif t==0x3F0D and l==8:dur=struct.unpack(">q",v)[0]
-        p2+=4+l
-      return max(0,isp+dur)
-  except:return 0
-  return 0
-mxf=sys.argv[1]
-while not os.path.exists(mxf) or os.path.getsize(mxf)<20000:time.sleep(0.3)
-with open(mxf,"rb") as f:hdr=f.read(200000)
-offs=[]
-for pat in [b"\x02\x02\x00\x08\xff\xff\xff\xff\xff\xff\xff\xff",b"\x30\x02\x00\x08\xff\xff\xff\xff\xff\xff\xff\xff"]:
-  p=0
-  while True:
-    i=hdr.find(pat,p)
-    if i<0:break
-    offs.append(i+4);p=i+1
-print("[dur-patch] %d Duration fields"%len(offs),flush=True)
-def patch(val):
-  if not offs:return
-  try:
-    with open(mxf,"r+b") as f:
-      for o in offs:f.seek(o);f.write(struct.pack(">q",val))
-  except Exception as e:print("[dur-patch] err:",e,flush=True)
-# Premiere rejects a growing OP1a/RDD9 whose header Duration is -1 on import
-# (bmx thread 87ac5750: Premiere prefers 0). raw2bmx writes -1 at clip-open, so
-# overwrite every -1 with 0 immediately, BEFORE any frames exist, then track the
-# live frame count every 3s.
-patch(0)
-print("[dur-patch] Duration=0 (initial)",flush=True)
-while True:
-  time.sleep(3)
-  fc=get_frames(mxf)
-  if fc>0:
-    patch(fc)
-    print("[dur-patch] Duration=%d"%fc,flush=True)
diff --git a/services/capture/src/capture-manager.js b/services/capture/src/capture-manager.js
index cdf9470..9d17959 100644
--- a/services/capture/src/capture-manager.js
+++ b/services/capture/src/capture-manager.js
@@ -738,13 +738,13 @@ for i in $(seq 1 200); do
   sleep 0.1
 done
 exec 7>&- 8>&-
-# Start the MXF header duration patcher (services/capture/dur-patch.py, shipped
-# to /app/dur-patch.py by the image build). It overwrites the header Duration=-1
-# fields with 0 immediately (Premiere rejects -1 on import; bmx thread 87ac5750)
-# and then with the live frame count every 3s, parsed from the last body
-# partition IndexTableSegment, so the clip grows in Premiere.
-python3 -u /app/dur-patch.py "$OUT" >&2 &
-PATCHPID=$!
+# No header-duration patcher is needed. In this bmx v1.6 build, raw2bmx's rdd9
+# writer with --part maintains a live, correct header Duration as the file grows
+# (verified on-node: ffprobe reads a growing duration mid-write, e.g. 2.04s of a
+# 10s clip while still recording). A patcher (the earlier dur-patch.py) was a
+# no-op here — it searched for Duration=-1, which rdd9 never writes — and opening
+# the file r+b while raw2bmx appends over CIFS only adds concurrency risk.
+PATCHPID=
 # Wait for ffmpeg (source end), then for raw2bmx to finalize the footer.
 wait "$FFPID"; FFRC=$?
 wait "$BMXPID"; BMXRC=$?