Here are direct links for the curious:
- https://patents.google.com/patent/US8588949B2
- https://patents.google.com/patent/US9195258B2
- https://patents.google.com/patent/US9219959B2
- https://patents.google.com/patent/US10209953B2
- https://patents.google.com/patent/US10439896B2
(Edit: Formatting)
- https://patents.google.com/patent/US8588949B2
The ability to add separate speakers to groups, and control their volume via a single master volume control.
- https://patents.google.com/patent/US9195258B2
Covers two speakers synchronising playback by exchanging timing information between themselves. This one is not very clearly written.
- https://patents.google.com/patent/US9219959B2
A playback device that receives audio from the network and then equalises and plays it back, with two different equalisation settings. (This is for stereo output with two smart speakers.)
- https://patents.google.com/patent/US10209953B2
This is just a better worded and more specific version of the second patent. It describes how you would use timing information to synchronise playback. It's nothing clever - just the very obvious solution of using pings to measure the clock differences between the devices and then delaying the audio appropriately.
- https://patents.google.com/patent/US10439896B2
This is a description of the standard way of setting up smart devices - they announce their presence, you connect to them directly, send the wifi details, and then they indicate they have connected. I bet they wish they had just written "device" instead of "playback device" in this patent because then literally every smart device in the world would be violating it!
I was at least expecting some sophisticated synchronisation or room measurement stuff. But no, just 5 obvious patents that should never have been granted.