JACK_DELAY(1)

✨ JACK_DELAY(1) ✨

okay bestie, so this is the manual page for jack_delay, a JACK sound card latency meter 🎀 and it is genuinely one of those tiny tools that ate and left no crumbs.

🌸 NAME 🌸

jack_delay — JACK sound card latency meter 💅

🦋 DESCRIPTION 🦋

so like, jack_delay is your girl for measuring the round-trip latency of a soundcard. fr fr. to do the thing, you start the program and wire it up like this:

jack_delay -> playback_port -> cable from soundcard output to input -> capture port -> jack_delay

and then she gets to work. jack_delay generates a signal made of 13 sine waves 🌈, measures the phase difference between the input and output for each of these, and computes the delay from those phase differences. the algorithm is the one originally developed for satellite ranging — aka measuring the distance between a satellite and a ground station 🛰️. iykyk.

with a good sound card, jack_delay will measure the round-trip latency with an accuracy of around 1/1000 of a sample. that's not a typo, bestie, that's precision. 💀✨

the assumption baked in here is that the delay is more or less independent of frequency. the actual value displayed is the one for a frequency of 1/16 of the sample rate. the phase measurement for this frequency of course only provides a result in the range of 0..16 samples 👑. the other frequencies are used to extend this interval to 4096 * 16 samples, which is more than a second at 48 kHz. the way that math just works — obsessed. 🔥

💖 OPTIONS 💖

• -h — Display this text 🙈
• -O <playback port> — connect output to named port. e.g. system:playback_1 🎧
• -I <capture port> — connect input to named port. e.g. system:capture_1 🎤
• -E — show excess latency instead of full latency. 👀

🌟 AUTHOR 🌟

jack_delay was written by Fons Adriaensen <fons@linuxaudio.org>. 🫶

this manual page was written by Jaromír Mikeš <mira.mikes@seznam.cz> for the Debian project (but may be used by others). 💜

and that's the whole vibe, bestie — manual page JACK_DELAY(1), dated August 2017, living its best life in the User Commands section. periodt. 💅✨🎀