retry content type through proxy

backend/stream.py

@@ -223,7 +223,15 @@ class MainHandler(tornado.web.RequestHandler):
             video_info = {}
             video_info["upstream"] = proxied[0]
             video_info["poster"] = proxied[1]
-            video_info["ctype"] = provider_data.ctype()
+
+            if isinstance(provider_data.ctype(), str):
+                video_info["ctype"] = provider_data.ctype()
+            else:
+                async with handler.proxy.local() as session:
+                    resp = await session.head(proxied[0])
+                    ctype = resp.headers.get("Content-Type", None)
+                    if isinstance(ctype, str):
+                        video_info["ctype"] = ctype
 
             script = template_script.generate(info=json.dumps(video_info))
             b64 = str(base64.b64encode(script), "ascii")