cef_browser: unconditionally write frame, start with transparent frame

src/overlay/obs/cef_browser.py

@@ -38,7 +38,7 @@ class CEFBrowserCapturer:
         self.dimensions = dimensions
         self.url = url
         self.outfile = outfile
-        self.frame = None
+        self.frame = b'\x00' * 4 * self.dimensions[0] * self.dimensions[1]
         self.rate = rate
 
         settings = {
@@ -58,20 +58,23 @@ class CEFBrowserCapturer:
         window_info.SetAsOffscreen(0)
         self.browser = cef.CreateBrowserSync(window_info=window_info, settings=browser_settings, url=self.url)
 
+    def __del__(self):
+        self.browser.CloseBrowser()
+        cef.Shutdown()
+
     def run_browser(self):
         self.browser.SetClientHandler(CEFHandler(self))
         self.browser.SendFocusEvent(True)
         self.browser.WasResized()
         cef.MessageLoop()
-        cef.Shutdown()
 
     def output_frames(self):
         with open(self.outfile, 'wb') as f:
+            frame_duration = 1.0 / self.rate
             while True:
                 t = time.monotonic()
-                if self.frame:
-                    f.write(self.frame)
-                time.sleep(1.0 / self.rate - (time.monotonic() - t))
+                f.write(self.frame)
+                time.sleep(max(0.0, frame_duration - (time.monotonic() - t)))
 
     def exit(self, browser=None):
         browser = browser or self.browser