Remote Control and Enhanced Metadata for AirPlay 2

[mikebrady]

Remote Control for AirPlay 2

We are thrilled to announce that remote control of AirPlay 2 players is becoming available with the development version of Shairport Sync 5.4-dev. In tandem with this, enhanced metadata is also available on the D-Bus interface for AirPlay 2 players.

You'll know that Shairport Sync has had remote control facilities for classic AirPlay players for some time -- for example, you could control play and volume and some more things via Shairport Sync's MPRIS, D-Bus or MQTT interfaces, but this only worked only on "classic" AirPlay (aka AirPlay 1) players, and "Advanced" controls were only available for iTunes or the macOS Music app.

Now, most of these remote control facilities are available on AirPlay 2 players using the same Shairport Sync commands and properties.

Update: It emerges that paintarm287 has been working on this independently, and we look forward to incorporating what they have deciphered!

Enhanced Metadata for Airplay 2

AirPlay 2 provides much more metadata than classic AirPlay. This is now provided on the D-Bus interface alongside existing metadata. Much of it has not been figured out.

More Details

• The MPRIS interface has been brought closer to the true MPRIS standard: Volume, LoopStatus and Shuffle are now settable properties as specified in the standard, whereas up to now they were read-only properties.
• The D-Bus interface has likewise been enhanced: Volume, LoopStatus and Shuffle are now settable properties. Most of the RemoteControl and AdvancedRemoteControl suite of commands and properties are available on AirPlay 2 connections.
• The D-Bus interface has two new properties: NowPlayingInformation and CommandInformation. Both of these are essentially raw feeds of metadata coming from AirPlay 2. The only exception is that raw picture data is removed from the NowPlayingInformation and is replaced by a local file reference to the same data.
• MPRIS and D-Bus interfaces now check parameters and report errors before accepting a command or setting a property.

Other Changes

• Some AirPlay 2 feature and status flags have been changed.
• The D-Bus and MPRIS test clients shairport-sync-dbus-test-client and shairport-sync-mpris-test-client have been updated to pretty-print the new metadata and command information.
• The sample metadata reader has similarly been updated to handle the new metadata and fix a few bugs.

Divergences between AirPlay 2 and classic AirPlay

Although many properties and features remain the same, not everything is quite the same between classic AirPlay and AirPlay 2 commands and metadata.

The Picture is Evolving!

This picture is changing as we develop more understanding.

Deprecations!

There will likely be deprecations as these facilities evolve. For example, AdvancedRemoteControl, duplicate Volume and SetVolume properties and methods will go away; AdvancedRemoteControl.Available and RemoteControl.Available may disappear, etc. In the MPRIS interface, the SetVolume method may disappear -- it's not part of the MPRIS standard and is not needed any more.