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AirPlay 2

Shairport Sync offers AirPlay 2 support for audio sources on iOS devices, Macs from macOS 10.15 (Catalina) onwards, HomePod minis and Apple TVs.

What Works

  • AirPlay 2 audio for iOS, HomePod mini, AppleTV and Mac players.

    • Audio is synchronised with other AirPlay 2 devices.
    • Two types of audio are received by Shairport Sync – "Realtime" streams of CD quality ALAC (like "classic" AirPlay) and "Buffered Audio" streams of AAC stereo at 44,100 frames per second.
    • The selection of stream type is made by the player.
    • Realtime streams generally have a latency of about two seconds. Buffered Audio streams typically have a latency of half a second or less.
    • In AirPlay 2 mode, Shairport Sync reverts to "classic" AirPlay when iTunes on macOS or macOS Music plays to multiple speakers and one of more of them is compatible with AirPlay only.

  • Devices running Shairport Sync in AirPlay 2 mode can be added to the Home app.

What Does Not Work

  • No AirPlay 2 for Windows iTunes.
  • Remote control facilities are not implemented.
  • AirPlay 2 from macOS prior to 10.15 (Catalina) is not supported.

General

Shairport Sync uses a companion application called NQPTP ("Not Quite PTP") for timing and synchronisation in AirPlay 2. NQPTP must run as root and must have exclusive access to ports 319 and 320.

Lossless and High Definition Lossless material is transcoded to AAC before it reaches Shairport Sync.

What You Need

AirPlay 2 support needs a slightly more powerful CPU for decoding and synchronisation and more memory for bigger buffers and larger libraries. A system with the power of a Raspberry Pi 2 or Raspberry Pi Zero 2 W, or better, is recommended.

Here are some guidelines:

  • Full access, including root privileges, to a system at least as powerful as a Raspberry Pi 2 or a Raspberry Pi Zero 2 W.
  • Ports 319 and 320 must be free to use (i.e. they must not be in use by another service such as a PTP service) and must not be blocked by a firewall.
  • An up-to-date Linux or FreeBSD. This is important, as some of the libraries must be the latest available.
  • Shairport Sync will not run in AirPlay 2 mode on a Mac because NQPTP, on which it relies, needs ports 319 and 320, which are already used by macOS.
  • A version of the FFmpeg library with an AAC decoder capable of decoding Floating Planar -- fltp -- material. There is a guide here to help you find out if your system has it.
  • An audio output, for example an ALSA device (or sndio in FreeBSD). The device must be capable of running at 44,100 frames per second. You can use sps-alsa-explore to test the suitability of hardware ALSA audio devices on your device. Other backends continue to work as with "classic" Shairport Sync.
  • Multiple instances of the AirPlay 2 version of Shairport Sync can not be hosted on the same system. It seems that AirPlay 2 clients are confused by having multiple AirPlay 2 players at the same IP addresses.

Guides

  • A building guide is available at BUILD.md.