ego viewer: guard/throttle slave-video sync (fixes head_fisheye_left seek-storm on cold load)

egoSample/mego.html

@@ -168,7 +168,11 @@ function loadSig(slug){
   const done=()=>{ SIG=window.EPDATA[slug]; if(!SIG) return; sizeCanvases(); drawCharts();
     let fv=0; for(let k=0;k<SIG.n;k++){ if(SIG.handL.valid[k]>0.5&&SIG.handR.valid[k]>0.5){ fv=k/SIG.fps; break; } }
     if(master && master.currentTime<0.05 && fv>0) setTime(fv); else if(master){ updateUI(master.currentTime||0); blitMain(); }
-    if(_toggle && !playing) _toggle(); };
+    // start playback only once the master tile can actually play, so the per-frame
+    // slave sync chases a real timestamp instead of hammering seeks against t=0
+    const go=()=>{ if(_toggle && !playing) _toggle(); };
+    if(!master) {} else if(master.readyState>=3) go();
+    else master.addEventListener('canplay', go, {once:true}); };
   if(window.EPDATA[slug]){ done(); return; }
   const s=document.createElement('script'); s.id='sigjs'; s.src='epdata/'+slug+'.js';
   s.onload=done; s.onerror=()=>{ SIG=null; };
@@ -349,18 +353,36 @@ function wire(){
   setTime(0);
 }
 
+// --- slave-video sync (k>0). Guarded + throttled so a still-buffering panel
+// (e.g. head_fisheye_left on a cold load) doesn't get a `currentTime=` write on
+// every rAF while its previous seek is still in flight — that restarts the seek
+// endlessly and the panel just replays its first few hundred ms.
+let _lastSync=0;
+function seekSlave(v,t){
+  if(v.seeking) return;          // a seek is already pending — never stack another
+  if(v.readyState<1) return;     // no metadata yet, nothing to seek to
+  try{ if(v.fastSeek) v.fastSeek(t); else v.currentTime=t; }catch(e){}
+}
+function syncSlaves(t,force){
+  const now=performance.now();
+  if(!force && now-_lastSync<180) return;   // ~5 Hz correction, not 60 Hz
+  _lastSync=now;
+  for(let k=1;k<vids.length;k++){ const v=vids[k];
+    if(Math.abs(v.currentTime-t)>0.18) seekSlave(v,t); }
+}
 function setTime(t){
   const dur=EP.duration; t=Math.max(0,Math.min(dur-0.01,t));
-  vids.forEach(v=>{ try{ if(Math.abs(v.currentTime-t)>0.05) v.currentTime=t; }catch(e){} });
+  try{ if(Math.abs(master.currentTime-t)>0.05) master.currentTime=t; }catch(e){}
+  syncSlaves(t,true);
   updateUI(t); blitMain(t);
 }
 function tick(){
   if(!playing) return;
   const t=master.currentTime, dur=EP.duration;
-  vids.forEach((v,k)=>{ if(k>0 && Math.abs(v.currentTime-t)>0.12){ try{v.currentTime=t;}catch(e){} } });
+  syncSlaves(t,false);
   updateUI(t);
   blitMain(t);
-  if(t>=dur-0.05){ vids.forEach(v=>{ try{v.currentTime=0;}catch(e){} }); updateUI(0); }
+  if(t>=dur-0.05){ try{master.currentTime=0;}catch(e){} syncSlaves(0,true); updateUI(0); }
   raf=requestAnimationFrame(tick);
 }
 /* draw the main (head_fisheye) frame + projected hand skeleton into one canvas */