Go Play 2

This is a working Airplay 2 Speaker implementation largely inspired by airplay2-receiver
The goal is to have an Opinionated implementation, with only some features but working very well.

Features

Can

• Play AAC 44100Hz with Apple Music (buffered audio)
• Play/Pause/Stop/Seek
• Homekit pairing with iPhone Home App
• Sync with HomePod mini
• PTP supported
• Working on a Rasbperry 1
• Set Volume
• Support PulseAudio (and can select sink)

Nexts

• P1 - Improve multi-room support (audio sync)
• P2 - Play ALAC
• P3 - Supports Spotify (RTP over UDP, type 96)
• P4 - NIC hardware timestamp (linux)

Will not support

• Windows build
• Track information
• Screen, Video, ... (other Airplay Features)
• Airplay 1
• NTP

Multi Room accuracy

• The accuracy is around 1ms of offset between clocks.
• Need to sync during playing (add silence of skip frames)

How to build ( works on Linux and MacOsX)

• Clone the repository

git clone https://github.com/openairplay/goplay2.git

• Build goplay2

go build  

Dependencies

You need to have portaudio-dev, pulseaudio and lib-fdk-aac and go runtime installed to build this program

Ubuntu 21.4 build

sudo apt install golang-go libfdk-aac-dev

Rasbpian (buster)

fdk-aac is not provided by default, you have to change your source.list (as root or using sudo)

echo "deb http://www.deb-multimedia.org buster main non-free" >> /etc/apt/sources.list
apt-get update -oAcquire::AllowInsecureRepositories=true
apt-get install deb-multimedia-keyring -y
apt-get install libfdk-aac-dev

You also need to install go from https://golang.org/dl/ as version 1.16 is not supplied by buster (they only support 1.11)

Mac os build

• Having xcode properly installed (clang needed)

brew install portaudio fdk-aac go 

Docker image

You can build and run the image to quickly test goplay, though this is experimental right now and comes with caveats.

• Build the image

The following platforms are supported: linux/amd64, linux/arm64, linux/arm/v7. Other platforms should also build.

You need at least docker 19.06.

To build:

docker buildx build -t you/goplay2 .

This is a multi-architecture image. If you have QEMU/Docker configured, you can target a different platform, or better, use buildctl and buildkit to produce a proper multi-architecture image.

• Run the container

This image currently does not provide a way to run pulseaudio inside the container itself, and pulseaudio is expected to be available and running on the host for this to work.

On debian variants, this is typically as simple as:

sudo apt-get install pulseaudio
pulseaudio --start

To then run the container

export STATION_NAME="GoplaySpeaker"

mkdir -p "$(pwd)/$STATION_NAME"

docker run \
	--rm \
	--name goplay \
	--volume "$(pwd)/$STATION_NAME":/opt/"$STATION_NAME" \
	--volume /run/user/1000/pulse/native:/pulse \
	--env PULSE_SERVER=/pulse \
	--net host \
	--cap-drop=ALL \
	--cap-add=NET_BIND_SERVICE \
	--read-only \
	you/goplay2 ./goplay2 -n "$STATION_NAME"

Note that mDNS by design will only work with networking mode "host" (recommended for beginners) or (mac/ip)vlan.

Acknowledgments

Run

• goplay2 by default run only on the ipv4 interface (because this issue on ipv6 parsing)

Linux

• goplay2 should not be run as root to use pulseaudio server
• goplay2 need to have special privileges to open PTP port (319,320)

to allow goplay2 to open port below 1024 you need to run

setcap 'cap_net_bind_service=+ep' ./goplay2 

nb: should be re-run every time you build goplay2

Parameters

delay (ms) is subtracted from the local "clock"
Ex: It takes around 60ms on my mac to launch the audio stream at the Anchor Time

i (interface) used to listen (by default eth0)

n (name) used as accessory name (Bonjour)

sink (pulse audio sink name) to replace default sink

Example :

./goplay2 -sink alsa_output -i en0 -n aiwa

By AlbanSeurat