diff --git a/src/video/ffmpeg.rs b/src/video/ffmpeg.rs
index 90aeb7d..0a340d5 100644
--- a/src/video/ffmpeg.rs
+++ b/src/video/ffmpeg.rs
@@ -273,7 +273,7 @@ pub async fn generate_preview_clip(input_file: &str, output_file: &str) -> Resul
         let interval = duration / segment_count as f64;
 
         let vf = format!(
-            "select='lt(mod(t,{:.4}),1)',setpts=N/30/TB,scale=-2:480",
+            "select='lt(mod(t,{:.4}),1)',setpts=N/FRAME_RATE/TB,fps=30,scale=-2:480",
             interval
         );
         let af = format!(