diff --git a/src-tauri/src/windows_player_surface.rs b/src-tauri/src/windows_player_surface.rs
index 16b698b..9bbe112 100644
--- a/src-tauri/src/windows_player_surface.rs
+++ b/src-tauri/src/windows_player_surface.rs
@@ -388,13 +388,20 @@ fn spawn_install_thread(app_handle: AppHandle, setup_tx: mpsc::Sender<Result<Nat
         let mut visible = false;
         let mut last_size = (init_w, init_h);
         let mut last_render_error: Option<String> = None;
+        // TEMP DEBUG: dump a screenshot a few seconds into playback to check
+        // whether decode itself is black or only the on-screen display is.
+        let mut frames_since_load: u32 = 0;
+        let mut took_debug_screenshot = false;
 
         loop {
             // Drain command channel.
             while let Ok(cmd) = receiver.try_recv() {
                 match cmd {
                     SurfaceCommand::Load { url, start_at, .. } => {
-                        log::info!("player surface: loading url={url} start_at={start_at:?}");
+                        log::info!(
+                            "player surface: loading url={url} start_at={start_at:?} surface_size={}x{}",
+                            last_size.0, last_size.1
+                        );
                         unsafe {
                             set_window_blur_behind(parent_hwnd, false);
                             ShowWindow(child_hwnd, SW_SHOW);
@@ -411,6 +418,8 @@ fn spawn_install_thread(app_handle: AppHandle, setup_tx: mpsc::Sender<Result<Nat
                             )
                         };
                         visible = true;
+                        frames_since_load = 0;
+                        took_debug_screenshot = false;
                         let _ = app.emit("native-player-show", ());
                         let state = app.state::<DesktopState>();
                         *state.eof_next_fired.lock().unwrap() = false;
@@ -490,6 +499,18 @@ fn spawn_install_thread(app_handle: AppHandle, setup_tx: mpsc::Sender<Result<Nat
                         } else {
                             last_render_error = None;
                         }
+                        // TEMP DEBUG: see comment on frames_since_load above.
+                        frames_since_load += 1;
+                        if frames_since_load == 180 && !took_debug_screenshot {
+                            took_debug_screenshot = true;
+                            let path = std::env::temp_dir().join("fluxa_debug_frame.png");
+                            let cmd = format!("screenshot-to-file \"{}\"", path.to_string_lossy().replace('\\', "/"));
+                            if let Err(e) = r.command_string(&cmd) {
+                                log::error!("player surface: debug screenshot failed: {e}");
+                            } else {
+                                log::info!("player surface: debug screenshot written to {}", path.display());
+                            }
+                        }
                     }
                 }
                 let swap_start = std::time::Instant::now();