From 42ba415e2c39cd1d784875cf87ee1d799b374e51 Mon Sep 17 00:00:00 2001
From: Cherokee <successage@gmail.com>
Date: Thu, 30 Apr 2026 17:12:31 +0800
Subject: [PATCH] fix: interpolated frames reuse previous composited frame, no
 redundant copy

The encoding loop was doing frame_lookup + copy + mask write for every
frame including interpolated gap-filler frames. Now only real
detections trigger a full composite; interpolated frames reuse the
previous frame's result (cv2.VideoWriter copies internally on write).
---
 nodes/actor_extractor.py | 29 ++++++++++++++++++++++++-----
 1 file changed, 24 insertions(+), 5 deletions(-)

diff --git a/nodes/actor_extractor.py b/nodes/actor_extractor.py
index 071afce..795f7ee 100644
--- a/nodes/actor_extractor.py
+++ b/nodes/actor_extractor.py
@@ -784,16 +784,35 @@ class VideoActorExtractor:
             if not segments_data:
                 continue
 
+            # Collect detected frame indices for this actor (to distinguish
+            # real detections from interpolated gap-filler frames)
+            detected_indices: set = set()
+            for aid in identity_to_actors[actor_id]:
+                detected_indices.update(long_actors[aid].frame_indices)
+
             # Convert bool-mask segments to BGR frames for encoding
+            # Interpolated frames reuse the previous composited frame (no copy)
             segments_bgr: List[List[np.ndarray]] = []
             for seg in segments_data:
                 bgr_frames = []
+                prev_composited = None
                 for fi, bool_mask, _ in seg:
-                    frame_bgr = frame_lookup.get(fi)
-                    if frame_bgr is None:
-                        frame_bgr = np.full((img_h, img_w, 3), bg_bgr, dtype=np.uint8)
-                    composited = frame_bgr.copy()
-                    composited[~bool_mask] = bg_bgr
+                    if fi in detected_indices:
+                        frame_bgr = frame_lookup.get(fi)
+                        if frame_bgr is None:
+                            frame_bgr = np.full(
+                                (img_h, img_w, 3), bg_bgr, dtype=np.uint8
+                            )
+                        composited = frame_bgr.copy()
+                        composited[~bool_mask] = bg_bgr
+                        prev_composited = composited
+                    elif prev_composited is not None:
+                        # Interpolated frame — reuse previous (cv2.VideoWriter
+                        # copies internally on write)
+                        composited = prev_composited
+                    else:
+                        composited = np.full((img_h, img_w, 3), bg_bgr, dtype=np.uint8)
+                        prev_composited = composited
                     bgr_frames.append(composited)
                 segments_bgr.append(bgr_frames)