How did Apple make this work??

Apple's HomePod minis can pair up into stereo pairs. But how do they do it? Resources mentioned in this video: - HomePod mini: https://www.apple.com/shop/buy-homepod/homepod-mini/midnight - IEEE 802.1AS: https://www.ida.liu.se/~sohsa65/courses/tsn-course-2021/stds/8021AS-2020.pdf - AirPlay 2 RS (open source project): https://github.com/lmcgartland/airplay2-rs - What is gPTP: https://blog.meinbergglobal.com/2024/03/27/what-is-gptp/ - What is PTP: https://en.wikipedia.org/wiki/Precision_Time_Protocol - Wireshark: https://www.wireshark.org - HomePod mini intro video: https://www.youtube.com/watch?v=cPakvOuwg48 - MacRumors buyers guide: https://buyersguide.macrumors.com/#Homepod-Mini Support me on Patreon: https://www.patreon.com/geerlingguy Sponsor me on GitHub: https://github.com/sponsors/geerlingguy Merch: https://www.redshirtjeff.com 2nd Channel: https://www.youtube.com/@GeerlingEngineering 3rd Channel: https://www.youtube.com/@Level2Jeff Contents: 00:00 - What did Apple do 01:22 - How hard can it be 06:36 - Now there are two 08:30 - Testing a stereo pair 09:46 - Wireshark 10:52 - WiFi snooping with Apple 12:46 - Finding gPTP 15:03 - Timing packets 17:09 - How PTP works 17:55 - Brief look at IEEE 802.1AS and AVB 19:51 - Apple using standards