Reuse codec_context on stream thread restart (#71942)

homeassistant/components/stream/core.py

@@ -395,6 +395,9 @@ class KeyFrameConverter:
         This is run by the worker thread and will only be called once per worker.
         """
 
+        if self._codec_context:
+            return
+
         # Keep import here so that we can import stream integration without installing reqs
         # pylint: disable=import-outside-toplevel
         from av import CodecContext