libobs: Update async texture when showing preloaded video

The previous preloaded video behavior updated the texture on preload
rather than when the video was shown, during which time the texture may
have been modified by other processes, resulting in the wrong frame
being displayed.

libobs/obs-source.c

@@ -2888,8 +2888,6 @@ obs_source_preload_video_internal(obs_source_t *source,
 	if (!frame)
 		return;
 
-	obs_enter_graphics();
-
 	if (preload_frame_changed(source, frame)) {
 		obs_source_frame_destroy(source->async_preload_frame);
 		source->async_preload_frame = obs_source_frame_create(
@@ -2897,13 +2895,8 @@ obs_source_preload_video_internal(obs_source_t *source,
 	}
 
 	copy_frame_data(source->async_preload_frame, frame);
-	set_async_texture_size(source, source->async_preload_frame);
-	update_async_textures(source, source->async_preload_frame,
-			      source->async_textures, source->async_texrender);
 
 	source->last_frame_ts = frame->timestamp;
-
-	obs_leave_graphics();
 }
 
 void obs_source_preload_video(obs_source_t *source,
@@ -2962,8 +2955,18 @@ void obs_source_show_preloaded_video(obs_source_t *source)
 	if (!obs_source_valid(source, "obs_source_show_preloaded_video"))
 		return;
 
+	if (!source->async_preload_frame)
+		return;
+
+	obs_enter_graphics();
+
+	set_async_texture_size(source, source->async_preload_frame);
+	update_async_textures(source, source->async_preload_frame,
+			      source->async_textures, source->async_texrender);
 	source->async_active = true;
 
+	obs_leave_graphics();
+
 	pthread_mutex_lock(&source->audio_buf_mutex);
 	sys_ts = (source->monitoring_type != OBS_MONITORING_TYPE_MONITOR_ONLY)
 			 ? os_gettime_ns()