diff --git a/.memory/worklog.json b/.memory/worklog.json
index 474e125..1e1ce2c 100644
--- a/.memory/worklog.json
+++ b/.memory/worklog.json
@@ -125,6 +125,13 @@
       "message": "auto-save 2026-05-12 17:12 (~3)",
       "hash": "e1bc89a",
       "files_changed": 3
+    },
+    {
+      "ts": "2026-05-12T17:17:49+08:00",
+      "type": "commit",
+      "message": "auto-save 2026-05-12 17:17 (~1)",
+      "hash": "4fd43e8",
+      "files_changed": 1
     }
   ]
 }
diff --git a/api/main.py b/api/main.py
index 4799feb..69c7709 100644
--- a/api/main.py
+++ b/api/main.py
@@ -194,39 +194,28 @@ async def pipeline_analyze(job_id: str, frame_count: int = KEYFRAME_COUNT) -> No
         ])
 
         n = max(1, min(int(frame_count), 20))
-        update(job, message=f"抽取 {n} 张关键帧…", progress=50)
+        update(job, message=f"抽取 {n} 张关键帧（均匀采样）…", progress=50)
         frames_dir = d / "frames"
         if frames_dir.exists():
             shutil.rmtree(frames_dir)
         frames_dir.mkdir(parents=True)
 
-        try:
+        # 均匀采样：在 duration / (n+1) 的等距时间点各抽 1 帧
+        # 用 -ss 在 -i 前 = fast seek，每张 < 0.5s
+        duration = max(float(job.duration or 1.0), 0.1)
+        step = duration / (n + 1)
+        for i in range(n):
+            t = step * (i + 1)
+            out = frames_dir / f"sample_{i:03d}.jpg"
             run([
-                "ffmpeg", "-y", "-i", str(mp4),
-                "-vf", "select='gt(scene,0.4)'",
-                "-fps_mode", "vfr",
-                "-frames:v", str(n * 3),
+                "ffmpeg", "-y",
+                "-ss", str(t),
+                "-i", str(mp4),
+                "-frames:v", "1",
                 "-pix_fmt", "yuvj420p",
                 "-q:v", "3",
-                str(frames_dir / "scene_%03d.jpg"),
+                str(out),
             ])
-        except Exception:
-            pass
-        scene_frames = sorted(frames_dir.glob("scene_*.jpg"))
-
-        if len(scene_frames) < n:
-            sample_count = n - len(scene_frames)
-            duration = job.duration or 1.0
-            step = duration / (sample_count + 1)
-            for i in range(sample_count):
-                t = step * (i + 1)
-                out = frames_dir / f"sample_{i:03d}.jpg"
-                run([
-                    "ffmpeg", "-y", "-ss", str(t), "-i", str(mp4),
-                    "-frames:v", "1",
-                    "-pix_fmt", "yuvj420p",
-                    "-q:v", "3", str(out),
-                ])
 
         all_frames = sorted(frames_dir.glob("*.jpg"))[:n]
         renamed: list[KeyFrame] = []