diff --git a/src/api/media_api.rs b/src/api/media_api.rs
index aec149c..b707958 100644
--- a/src/api/media_api.rs
+++ b/src/api/media_api.rs
@@ -404,13 +404,22 @@ async fn trace_video(
         y_pos -= 22;
     }
 
-    // Green thin bounding boxes with trace_id label for each face detection
+    // Bounding boxes: interpolated (thickness=1) + actual (thickness=4) with trace_id label
     for (tid, frames) in &sorted_traces {
+        let range_enable = format!("between(n,{},{})", frames[0] as i64 - frame_offset, frames[frames.len() - 1] as i64 - frame_offset);
+        // Interpolated bbox at first known position across the whole trace range
+        if let Some((x, y, w, h)) = bbox_per_frame.get(&(*tid, frames[0])) {
+            parts.push(format!(
+                "drawbox=x={}:y={}:w={}:h={}:color=green@0.3:thickness=1:enable='{}'",
+                x, y, w, h, range_enable
+            ));
+        }
+        // Actual detection bboxes with trace_id label
         for fn_ in frames.iter() {
             if let Some((x, y, w, h)) = bbox_per_frame.get(&(*tid, *fn_)) {
                 let n = *fn_ as i64 - frame_offset;
                 parts.push(format!(
-                    "drawbox=x={}:y={}:w={}:h={}:color=green@0.5:thickness=1:enable='between(n,{},{})'",
+                    "drawbox=x={}:y={}:w={}:h={}:color=green@0.5:thickness=4:enable='between(n,{},{})'",
                     x, y, w, h, n, n
                 ));
                 parts.push(format!(