There are already a lot of MQTT Integrations to enable interoperability between different systems, programming languages etc.
Sadly though, there isn’t one for the media_player class which is why I’m opening this feature request.
The reasoning for why this should exist is the same as for every other mqtt component.
+1 on this. I use Sonos Connect connected to a Lectrosonics DM1624 which I created a sort of integration for.
This unit can matrix mix any input to any output, and this works perfectly for my use, but I am missing a flexible “media_player” in HA which can only control input (integer or string) and volume.
I have build one for my musiccast2mqtt bridge. Its working with inputs / volume / soundprograms etc.
Have a look at Multiroom Mqtt Mediaplayer