Super simple low latency windows system audio streaming

Due to a regretable headset cable incident, I ended up needing to stream low latency system audio (I.E. everything you’d hear from your PC) over a network to another computer. And when I say low latency, I mean low enough that I can still play a video game or youtube video without there being enough of a difference to be distracting. Turns out this is actually pretty easy and you can just use ffmpeg1.

The key thing here is the “Stereo Mix” audio device on Windows. It is a “virtual” recording device which provides, as an input, the current audio output thats going to your default playback device. It’s not enabled by default, and also seems to be provided by the manufacturers audio drivers - I had to install a driver package from the manufacturer of the audio chipset in my system (as opposed to just using the default windows drivers) to get it to show up.

This done, we can now run ffmpeg on the source machine.

ffmpeg.exe -f dshow -audio_buffer_size 50 -i audio="Stereo Mix (Realtek High Definition Audio)" -f s16le udp://

to break this down a little:

Then, on the receiving side…

ffplay -i udp:// -f s16le -ac 2

Again, to break this down:

So anyway, that’s about it. Nothing very special going on here. I was pleasantly suprised at how usable and low latency this was - there’s a perceivable delay, but it’s not distractingly large. I was also surprised that this works remarkably well over the internet too, so long as your upload bandwidth is sufficient!

  1. Because of course it can ↩︎