TO get better features and fix for chromecast and miracast one just needs to join beta and get exclusive updates for apps
most important ones are
-chromecast one https://play.google.com/apps/testing/com.google.android.apps.mediashell
-google play services Test d'application Android – Google Play
the two contains all the things to miracast or chromecast stuff
wanted to share the link
ps you even got an app dedicated to beta program TestingCatalog: Apps for Beta Testing – Applications sur Google Play
As for me it fixed all chromecast issues like audio off on while playing content etc....
CHEERS
Are you talking about issues playing a video with audio in an unsupported codec (like EC3)? The symptom would be that the video plays silently without any audio. If so, I've also been able to solve it recently in a different way.