Mask timecode in phase refine and guard cutter scene starts

docs/ALGORITHM.md

@@ -170,9 +170,10 @@ Der zusätzliche Hi-Res-Phasenrefine bleibt lokal um den bereits validierten
 Inpoint und übernimmt nur klare Verbesserungen. Er darf keine ganze lange
 Dialogszene nach ähnlichen Layouts durchsuchen, weil sonst dieselbe Location
 mit anderer Gestik als falsche Phase gewinnen kann und die Laufzeit explodiert.
-Report-Clips werden zusätzlich an den bekannten Source-Szenenstart geklemmt,
-damit ein knapp vor der Schnittkante liegender Inpoint nicht mit Frames der
-vorherigen Einstellung beginnt.
+Report-Clips werden zusätzlich an den bekannten Source-Szenenstart plus eine
+kurze Guard-Zone geklemmt, damit ein knapp vor oder direkt auf der Schnittkante
+liegender Inpoint nicht mit Frames der vorherigen Einstellung oder einer zu
+frühen Übergangsphase beginnt.
 
 ## Multi-Shot-Beats
 

scripts/generate_cutter_report.py

@@ -120,6 +120,7 @@ STILL_WIDTH = 480
 STILL_QUALITY = 4
 CLIP_WIDTH = 480
 CLIP_MAX_DURATION_S = 30.0
+SCENE_START_GUARD_S = 0.32
 # Each half of the side-by-side compare strip
 COMPARE_HALF_W = 480
 COMPARE_H = 270   # 16:9
@@ -423,18 +424,26 @@ def collect_rows(
             num_segs = len(segs)
             if scenes_by_id:
                 rec_scene = scenes_by_id.get(int(rec.get("scene_id", -1)))
-                if rec_scene and float(rec["in_point_s"]) < float(rec_scene["start_s"]):
-                    shift = float(rec_scene["start_s"]) - float(rec["in_point_s"])
+                if rec_scene and float(rec["in_point_s"]) < float(rec_scene["start_s"]) + SCENE_START_GUARD_S:
+                    guarded_start = min(
+                        float(rec_scene["end_s"]) - 0.04,
+                        float(rec_scene["start_s"]) + SCENE_START_GUARD_S,
+                    )
+                    shift = guarded_start - float(rec["in_point_s"])
                     rec = dict(rec)
-                    rec["in_point_s"] = float(rec_scene["start_s"])
+                    rec["in_point_s"] = guarded_start
                     rec["out_point_s"] = max(float(rec["in_point_s"]) + 0.04, float(rec["out_point_s"]) + shift)
                 fixed_segs = []
                 for seg in segs:
                     fixed = dict(seg)
                     seg_scene = scenes_by_id.get(int(fixed.get("scene_id", -1)))
-                    if seg_scene and float(fixed["in_point_s"]) < float(seg_scene["start_s"]):
-                        shift = float(seg_scene["start_s"]) - float(fixed["in_point_s"])
-                        fixed["in_point_s"] = float(seg_scene["start_s"])
+                    if seg_scene and float(fixed["in_point_s"]) < float(seg_scene["start_s"]) + SCENE_START_GUARD_S:
+                        guarded_start = min(
+                            float(seg_scene["end_s"]) - 0.04,
+                            float(seg_scene["start_s"]) + SCENE_START_GUARD_S,
+                        )
+                        shift = guarded_start - float(fixed["in_point_s"])
+                        fixed["in_point_s"] = guarded_start
                         fixed["out_point_s"] = max(float(fixed["in_point_s"]) + 0.04, float(fixed["out_point_s"]) + shift)
                     fixed_segs.append(fixed)
                 segs = fixed_segs

src/cv/global_scan.py

@@ -206,7 +206,12 @@ def _hires_phase_feature(frame: np.ndarray) -> np.ndarray:
     with an 8×8 spatial histogram grid provides enough spatial resolution to
     discriminate facial expression phases within a single continuous scene.
     """
-    trimmed = _trim_dark_borders(frame)
+    trimmed = _trim_dark_borders(frame).copy()
+    h0, w0 = trimmed.shape[:2]
+    # Source and trailer masters often contain burned-in timecode in the
+    # upper-left corner.  It changes every frame and can dominate fine phase
+    # matching, so neutralise that area before extracting hi-res features.
+    trimmed[: int(h0 * 0.16), : int(w0 * 0.28)] = 0
     h, w = trimmed.shape[:2]
     cropped = trimmed[int(h * 0.05):int(h * 0.95), :]
     gray = cv2.cvtColor(cropped, cv2.COLOR_BGR2GRAY)