From d984fb1bae75dacd503e7c1226cc606424107532 Mon Sep 17 00:00:00 2001
From: David <49467229+TheSecurityDev@users.noreply.github.com>
Date: Mon, 16 Feb 2026 16:32:37 -0600
Subject: [PATCH] ui diff replay: better display replays of different lengths
 (#37116)

* refactor: improve video synchronization logic in HTML report generation

* feat: include description of which video is longer in report; refactor stuff and add types

* refactor: simplify HTML report generation and remove extra formatting

* reduce diff

* fix video name

* reduce diff

* reduce diff

* fix

* parentheses

* fix I guess
---
 selfdrive/ui/tests/diff/diff.py | 117 ++++++++++++++++----------------
 1 file changed, 58 insertions(+), 59 deletions(-)

diff --git a/selfdrive/ui/tests/diff/diff.py b/selfdrive/ui/tests/diff/diff.py
index f2b88a3ca..42efa381b 100755
--- a/selfdrive/ui/tests/diff/diff.py
+++ b/selfdrive/ui/tests/diff/diff.py
@@ -31,19 +31,13 @@ def create_diff_video(video1, video2, output_path):
   subprocess.run(cmd, capture_output=True, check=True)
 
 
-def find_differences(video1, video2):
+def find_differences(video1, video2) -> tuple[list[int], tuple[int, int]]:
   print(f"Hashing frames from {video1}...")
   hashes1 = extract_framehashes(video1)
 
   print(f"Hashing frames from {video2}...")
   hashes2 = extract_framehashes(video2)
 
-  if len(hashes1) != len(hashes2):
-    print(f"WARNING: Frame count mismatch: {len(hashes1)} vs {len(hashes2)}")
-    min_frames = min(len(hashes1), len(hashes2))
-    hashes1 = hashes1[:min_frames]
-    hashes2 = hashes2[:min_frames]
-
   print(f"Comparing {len(hashes1)} frames...")
   different_frames = []
 
@@ -51,10 +45,10 @@ def find_differences(video1, video2):
     if h1 != h2:
       different_frames.append(i)
 
-  return different_frames, len(hashes1)
+  return different_frames, (len(hashes1), len(hashes2))
 
 
-def generate_html_report(video1, video2, basedir, different_frames, total_frames, diff_video_name):
+def generate_html_report(videos: tuple[str, str], basedir: str, different_frames: list[int], frame_counts: tuple[int, int], diff_video_name):
   chunks = []
   if different_frames:
     current_chunk = [different_frames[0]]
@@ -66,66 +60,70 @@ def generate_html_report(video1, video2, basedir, different_frames, total_frames
         current_chunk = [different_frames[i]]
     chunks.append(current_chunk)
 
+  total_frames = max(frame_counts)
+  frame_delta = frame_counts[1] - frame_counts[0]
+  different_total = len(different_frames) + abs(frame_delta)
+
   result_text = (
     f"✅ Videos are identical! ({total_frames} frames)"
-    if len(different_frames) == 0
-    else f"❌ Found {len(different_frames)} different frames out of {total_frames} total ({(len(different_frames) / total_frames * 100):.1f}%)"
+    if different_total == 0
+    else f"❌ Found {different_total} different frames out of {total_frames} total ({different_total / total_frames * 100:.1f}%)."
+    + (f" Video {'2' if frame_delta > 0 else '1'} is longer by {abs(frame_delta)} frames." if frame_delta != 0 else "")
   )
 
+  def render_video_cell(video_id: str, title: str, path: str, is_diff=False):
+    return f"""
+<td width='33%'>
+  <p><strong>{title}</strong></p>
+  <video id='{video_id}' width='100%' autoplay muted {'' if is_diff else "onplay='syncVideos()'"}>
+    <source src='{os.path.join(basedir, os.path.basename(path))}' type='video/mp4'>
+    Your browser does not support the video tag.
+  </video>
+</td>
+"""
+
   html = f"""<h2>UI Diff</h2>
 <table>
 <tr>
-<td width='33%'>
-  <p><strong>Video 1</strong></p>
-  <video id='video1' width='100%' autoplay muted loop onplay='syncVideos()'>
-    <source src='{os.path.join(basedir, os.path.basename(video1))}' type='video/mp4'>
-    Your browser does not support the video tag.
-  </video>
-</td>
-<td width='33%'>
-  <p><strong>Video 2</strong></p>
-  <video id='video2' width='100%' autoplay muted loop onplay='syncVideos()'>
-    <source src='{os.path.join(basedir, os.path.basename(video2))}' type='video/mp4'>
-    Your browser does not support the video tag.
-  </video>
-</td>
-<td width='33%'>
-  <p><strong>Pixel Diff</strong></p>
-  <video id='diffVideo' width='100%' autoplay muted loop>
-    <source src='{os.path.join(basedir, diff_video_name)}' type='video/mp4'>
-    Your browser does not support the video tag.
-  </video>
-</td>
+{render_video_cell("video1", "Video 1", videos[0])}
+{render_video_cell("video2", "Video 2", videos[1])}
+{render_video_cell("diffVideo", "Pixel Diff", diff_video_name, is_diff=True)}
 </tr>
 </table>
 <script>
+const videos = [
+  document.getElementById('video1'),
+  document.getElementById('video2'),
+  document.getElementById('diffVideo'),
+];
+
+const isEnded = (v) => v.ended || (Number.isFinite(v.duration) && v.currentTime >= (v.duration - 0.05));
+const playAll = () => videos.forEach((v) => v.play());
+
 function syncVideos() {{
-  const video1 = document.getElementById('video1');
-  const video2 = document.getElementById('video2');
-  const diffVideo = document.getElementById('diffVideo');
-  video1.currentTime = video2.currentTime = diffVideo.currentTime;
+  const t = Math.min(...videos.map((v) => v.currentTime));
+  videos.forEach((v) => {{ v.currentTime = t; }});
+  playAll();
 }}
-video1.addEventListener('timeupdate', () => {{
-  if (Math.abs(video1.currentTime - video2.currentTime) > 0.1) {{
-    video2.currentTime = video1.currentTime;
-  }}
-  if (Math.abs(video1.currentTime - diffVideo.currentTime) > 0.1) {{
-    diffVideo.currentTime = video1.currentTime;
-  }}
-}});
-video2.addEventListener('timeupdate', () => {{
-  if (Math.abs(video2.currentTime - video1.currentTime) > 0.1) {{
-    video1.currentTime = video2.currentTime;
-  }}
-  if (Math.abs(video2.currentTime - diffVideo.currentTime) > 0.1) {{
-    diffVideo.currentTime = video2.currentTime;
-  }}
-}});
-diffVideo.addEventListener('timeupdate', () => {{
-  if (Math.abs(diffVideo.currentTime - video1.currentTime) > 0.1) {{
-    video1.currentTime = diffVideo.currentTime;
-    video2.currentTime = diffVideo.currentTime;
+
+function handleEnded(endedVideo) {{
+  endedVideo.pause();
+  if (videos.every(isEnded)) {{
+    videos.forEach((v) => {{ v.currentTime = 0; }});
+    playAll();
   }}
+}}
+
+videos.forEach((v) => {{
+  v.addEventListener('timeupdate', () => {{
+    videos.forEach((other) => {{
+      if (other !== v && !isEnded(other) && Math.abs(v.currentTime - other.currentTime) > 0.1) {{
+        other.currentTime = v.currentTime;
+        if (other.paused) other.play();
+      }}
+    }});
+  }});
+  v.addEventListener('ended', () => handleEnded(v));
 }});
 </script>
 <hr>
@@ -162,14 +160,14 @@ def main():
   diff_video_path = str(DIFF_OUT_DIR / diff_video_name)
   create_diff_video(args.video1, args.video2, diff_video_path)
 
-  different_frames, total_frames = find_differences(args.video1, args.video2)
+  different_frames, frame_counts = find_differences(args.video1, args.video2)
 
   if different_frames is None:
     sys.exit(1)
 
   print()
   print("Generating HTML report...")
-  html = generate_html_report(args.video1, args.video2, args.basedir, different_frames, total_frames, diff_video_name)
+  html = generate_html_report((args.video1, args.video2), args.basedir, different_frames, frame_counts, diff_video_name)
 
   with open(DIFF_OUT_DIR / args.output, 'w') as f:
     f.write(html)
@@ -179,7 +177,8 @@ def main():
     print(f"Opening {args.output} in browser...")
     webbrowser.open(f'file://{os.path.abspath(DIFF_OUT_DIR / args.output)}')
 
-  return 0 if len(different_frames) == 0 else 1
+  extra_frames = abs(frame_counts[0] - frame_counts[1])
+  return 0 if (len(different_frames) + extra_frames) == 0 else 1
 
 
 if __name__ == "__main__":