d3d11: Fix deadlock while doing unprepare

ShowWindow() could be blocked while doing gst_d3d11_window_win32_unprepare
when external window handle provided to d3d11videosink in multi-threaded
environment.
The condition that issue happened is, UI thread is waiting for a
background thread that changes d3d11videosink state to NULL, and the
background thread would try to send a window message to the queue.
The queue is already occupied by the UI thread, so the background
thread will be blocked.

Part-of: <https://gitlab.freedesktop.org/gstreamer/gstreamer/-/merge_requests/1366>

diff --git a/subprojects/gst-plugins-bad/sys/d3d11/gstd3d11window_win32.cpp b/subprojects/gst-plugins-bad/sys/d3d11/gstd3d11window_win32.cpp
index 6261c97..cba1031 100644 (file)
--- a/subprojects/gst-plugins-bad/sys/d3d11/gstd3d11window_win32.cpp
+++ b/subprojects/gst-plugins-bad/sys/d3d11/gstd3d11window_win32.cpp
@@ -208,7 +208,6 @@ gst_d3d11_window_win32_unprepare (GstD3D11Window * window)
   if (self->external_hwnd) {
     gst_d3d11_window_win32_release_external_handle (self->external_hwnd);
     RemoveProp (self->internal_hwnd, D3D11_WINDOW_PROP_NAME);
-    ShowWindow (self->internal_hwnd, SW_HIDE);
 
     if (self->internal_hwnd_thread == g_thread_self ()) {
       /* State changing thread is identical to internal window thread.