How to Sync Audio and Video on macOS (Step-by-Step Guide)

If you’re a YouTuber or streamer, you’re probably familiar with that incredibly frustrating moment when your video is perfect, but the audio is out of sync, just like a bad dubbing in an old 80s kung-fu movie.

This was exactly the issue I had with our YouTube channel (by the way, if you’re not subscribed yet, what are you waiting for? SUBSCRIBE NOW!!!). For my tutorial videos, I use a small Canon camera connected to an HDMI capture box, along with an XLR microphone connected to an external sound card. All this is done on macOS.

However, when I record a video, I consistently experience a delay between the audio and the video. This is normal; they don’t use the same channels, and I have some extra processing on the sound to remove background noise, plus a few tweaks to make it sound a bit more “radio-like.”

Until now, I recorded with OBS, setting a small delay of 200 ms to reduce this lag. The problem is that this forces me to go through OBS, and it isn’t precise. I set it to 200 ms, but maybe 198 ms or 205 ms would be better… I really don’t know; it’s been a guessing game after numerous tests.

Then I switched to a new recording tool, and there wasn’t any option to set a delay like in OBS. Sigh. And resynchronizing the audio in post-production? There’s nothing more tedious. It’s like trying to enjoy a big kebab without getting sauce everywhere.

Anyway… I did some research and discovered a native solution for macOS that I was completely unaware of. It’s a tool called “Audio and MIDI Setup” in macOS utilities that allows you to aggregate devices and, most importantly, synchronize them with their internal clock. It’s one of those hidden gems that can save your life.

And it works perfectly!!! No more guesswork with delays; it’s all about perfect synchronization. Here’s how to do it in a few simple steps:

First, launch the Audio and MIDI Setup utility, click the “+” at the bottom left [1], and create an aggregate device [2].

Next, check the devices you want to aggregate [1] and verify which device will control the drift [2]. In my case, I have my Elgato capture card as the reference device, corresponding to my camera, and the one being corrected is Blackhole 2ch, which is my audio device (my microphone).

You can also see at the top that the clock source is Elgato (my capture card), confirming it is the reference and that Blackhole 2ch is the sub-device. This configuration allows macOS to automatically adjust the synchronization in real-time.

Then, name it whatever you like [1] and, through a right-click, set this new device to be used as the default “audio input” [2].

And that’s it… Now in any capture software, you can specify this new aggregate device as your input device, and you’ll see that the audio is perfectly synchronized! Incredible! No more manual delays or hours wasted in post-production.

This trick works great because macOS uses the internal clock of the reference device (in my case, the camera) to dynamically adjust the synchronization of other devices. It’s much more precise than a fixed delay as the system adapts in real-time to possible variations.

So simple… Good recording to all, and see you soon!