Silent Rave Server

This repo contains the necessary tooling for organizing a silent rave, bring-your-own-device style, everyone with their own headphones.

• FastAPI + Uvicorn server streaming live music through HLS protocol.
• NGINX reverse proxy to better serve index.html and HLS files/playlist
• Mac Client for forwarding all live audio from BlackHole (or any loopback device) to the server. Audio is uploaded through HTTP.

Last time, I hosted everything on a Google Cloud Compute Engine instance with something like 4GB ram and 4 CPUs. Note, for some reason audio is broken when directly attempting to read the loopback device from ffmpeg. Instead, reading the audio from SOX and piping to ffmpeg through stdout works!

How to use?

Start the server (from cloud instance)

./run-server.sh

Start the streaming client (on your mac)

./stream-from-mac.sh

Play music from any source: YouTube, Spotify, Ableton Live, your DJ software. Make sure to select the Blackhole 2ch output device.

Check out the web page where appropriate. You should see something like this.

Setup "Guide"

The following are more notes than an actual guide to set everything up.

• Install BlackHole driver
• Create a multi output device
• Install Pyaudio.
• Install sox

brew install portaudio
pip3 install pyaudio pydub
brew install ffmpeg

My server https://console.cloud.google.com/compute/instances?onCreate=true&project=naivepsychology-22c0e

Debug: stream to file

ffmpeg -f avfoundation -i ":0" -c:a aac -b:a 128k -vn -hls_time 2 -hls_list_size 5 -hls_flags delete_segments -f hls output.m3u8

SSH to gogole cloud

gcloud compute ssh --zone "northamerica-northeast1-a" "silent-rave" --project "naivepsychology-22c0e"

Make sure to configure HTTP ports correctly! (VPC network section)

Find the device name on mac (Blackhole 2ch?)

ffmpeg -list_devices true -f avfoundation -i dummy
sox -V6 -n -t coreaudio junkname  # "BlackHole 2ch"

Start nginx

sudo systemctl reload nginx
sudo systemctl start nginx

Limitations

• Audio sync seems to be +/- 10 sec which is not great but usable.
• I haven't figured out HTTPS stuff, so everything is pretty insecure now. lol