audioOS 12.1.1 (build 16C50) is an official Apple over-the-air update for the HomePod (Unknown Model), released on 2018-12-05T18:07:04Z. The update package is 1.4 GB. This is a delta (partial) update that requires 11.4 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: 40befb3b8f812836b4f37e863c61e9cfc6735865.zip.