diff --git a/src/video/actors.rs b/src/video/actors.rs
index a461efe..c7300ef 100644
--- a/src/video/actors.rs
+++ b/src/video/actors.rs
@@ -55,6 +55,16 @@ pub fn playlist_file_for(playlist_dir: &str, video_path: &Path) -> PathBuf {
     PathBuf::from(format!("{}/{}.m3u8", playlist_dir, filename))
 }
 
+/// Sentinel path written next to a would-be playlist when ffmpeg cannot
+/// transcode the source (e.g. truncated mp4 with no moov atom). Its presence
+/// causes future scans to skip the file instead of re-running ffmpeg every
+/// pass. Delete the `.unsupported` file to force a retry.
+pub fn playlist_unsupported_sentinel(playlist_file: &Path) -> PathBuf {
+    let mut s = playlist_file.as_os_str().to_owned();
+    s.push(".unsupported");
+    PathBuf::from(s)
+}
+
 pub async fn create_playlist(video_path: &str, playlist_file: &str) -> Result<Child> {
     if Path::new(playlist_file).exists() {
         debug!("Playlist already exists: {}", playlist_file);
@@ -319,7 +329,10 @@ impl Handler<ScanDirectoryMessage> for VideoPlaylistManager {
             .filter_map(|e| e.ok())
             .filter(|e| e.file_type().is_file())
             .filter(is_video)
-            .filter(|e| !playlist_file_for(&playlist_dir_str, e.path()).exists())
+            .filter(|e| {
+                let playlist = playlist_file_for(&playlist_dir_str, e.path());
+                !playlist.exists() && !playlist_unsupported_sentinel(&playlist).exists()
+            })
             .collect::<Vec<DirEntry>>();
 
         let scan_dir_name = msg.directory.clone();
@@ -393,7 +406,8 @@ impl Handler<QueueVideosMessage> for VideoPlaylistManager {
         let playlist_generator = self.playlist_generator.clone();
 
         for video_path in msg.video_paths {
-            if playlist_file_for(&playlist_dir_str, &video_path).exists() {
+            let playlist = playlist_file_for(&playlist_dir_str, &video_path);
+            if playlist.exists() || playlist_unsupported_sentinel(&playlist).exists() {
                 continue;
             }
             let path_str = video_path.to_string_lossy().to_string();
@@ -683,6 +697,20 @@ impl Handler<GeneratePlaylistMessage> for PlaylistGenerator {
                 };
                 error!("ffmpeg failed for {}: {}", video_file, detail);
                 cleanup_partial_hls(&playlist_tmp, playlist_path.as_str(), video_stem).await;
+                let sentinel = playlist_unsupported_sentinel(Path::new(&playlist_file));
+                if let Err(se) = tokio::fs::write(&sentinel, b"").await {
+                    warn!(
+                        "Failed to write playlist sentinel {}: {}",
+                        sentinel.display(),
+                        se
+                    );
+                } else {
+                    info!(
+                        "Wrote playlist sentinel {} so future scans skip {}",
+                        sentinel.display(),
+                        video_file
+                    );
+                }
                 span.set_status(Status::error(detail.clone()));
                 Err(std::io::Error::other(detail))
             }