Audio lag on a Mac almost always comes from outside the Mac itself: the Bluetooth codec your headphones negotiate, the processing a TV or receiver does before it plays a sound, or a Multi-Output Device forced to wait for its slowest member. macOS controls very little of this directly.
None of these are settings hiding in System Settings, and none of them are things any app, including Chorus, can switch off. They come from limits in the Bluetooth protocol or from processing happening inside other hardware entirely. What follows is where each delay actually comes from, which ones you can do something about, and the one place Chorus is genuinely relevant even though it cannot remove any of the lag itself.
Why does Bluetooth audio lag behind video?
Every Bluetooth headphone and speaker has to encode audio, send it over the air, and decode it again before it plays, and the codec in use decides how long that takes. SBC is the baseline codec every Bluetooth device supports, and it carries real, noticeable latency, commonly somewhere in the 150 to 270 millisecond range depending on the device and the connection. AAC is far better on Apple hardware: AirPods and most Apple-made accessories negotiate it automatically, roughly halving that delay. aptX Low Latency goes further still, built specifically to bring the gap down to around 40 milliseconds, but it only exists on devices whose chipset supports it, which on a Mac usually means non-Apple headphones rather than AirPods.
macOS negotiates the codec automatically with whatever the connected device offers. There is no menu toggle in System Settings that lets you force AAC or aptX Low Latency over SBC. The fix, when there is one, is almost always a different device or a different connection, not a setting on the Mac.
When it's the app, not the device
Some apps and browsers apply their own fixed audio and video sync offset, tuned on the assumption that sound is coming from a wired output with close to no delay of its own. Video players and video call apps commonly bake in an offset of roughly 20 to 80 milliseconds to smooth over normal playback timing. Over a wired output that offset is barely noticeable. Over Bluetooth, the device's own codec delay stacks on top of it, so a 200 millisecond SBC delay plus an app's own 50 millisecond offset becomes 250 milliseconds of lag rather than either number alone. Two delays that were each designed to be tolerable add up to one that is not.
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Download for MacWhy is my TV or receiver's audio delayed over HDMI?
HDMI carries video and audio down the same cable, but the device on the receiving end often processes the audio before it plays it: decoding Dolby Digital or DTS surround, running room correction, or applying its own upmixing. That processing takes real, measurable time, commonly somewhere between 30 and 150 milliseconds depending on which modes are switched on, and it happens entirely inside the TV or receiver, separate from anything the Mac is sending. Most TVs and receivers have their own "lip sync" or audio delay setting built to compensate for exactly this. That setting lives on the TV or receiver, not on the Mac, because that is where the delay is actually being added.
A Multi-Output Device inherits its slowest member's delay
Group two or more outputs together, using Audio MIDI Setup's built-in Multi-Output Device or the same mechanism inside Chorus, and macOS has to keep every device in the group playing the identical audio in lockstep. That means the whole group can only play as fast as its slowest member. Combine a wired speaker with a Bluetooth speaker running SBC, and the wired speaker, which on its own would have close to no delay, now waits for the Bluetooth one every time.
This is the one place Chorus is genuinely relevant, though not as a fix for the underlying delay. Chorus cannot make a Bluetooth codec faster or make a TV process sound quicker; those are hardware and protocol limits no app can remove. What Chorus does is make the tradeoff manageable: with every device visible in one list and a keyboard shortcut bound to each output and group, you can drop the slow Bluetooth speaker out of the group in a second, or switch straight to a single low-latency output, whenever timing matters more than having every speaker playing at once, then switch back to the full group afterwards.
Buffer size, if you're monitoring live input
This one only matters if you record or perform through a Mac. Professional audio apps like Logic Pro, GarageBand and other digital audio workstations let you set a buffer size, and it trades latency against stability. A small buffer, say 128 samples, gives a low round-trip delay of roughly 3 milliseconds at a 44.1kHz sample rate, useful for hearing a live vocal or instrument back while you record it, but it risks audible dropouts if the Mac cannot keep up. A larger buffer, say 512 samples, is far more stable but pushes that same round trip to roughly 12 milliseconds before the audio interface's own delay is even added. This setting lives inside the app's own audio preferences, has nothing to do with Bluetooth, HDMI or Multi-Output Devices, and only matters while you are actively monitoring a live input.
For the full pairing and troubleshooting detail, see Apple's own guide to connecting Bluetooth devices.
Frequently asked questions
Why does Bluetooth audio lag behind video on a Mac?
Bluetooth headphones and speakers have to encode, send and decode audio before it plays, and the codec macOS negotiates decides how much delay that adds. SBC, the baseline codec every Bluetooth device supports, has real, noticeable latency. AAC is much better on Apple hardware and is used automatically with AirPods and most Apple-made accessories. aptX Low Latency, on devices that support it, is built specifically to cut this delay further.
Can I choose which Bluetooth codec my Mac uses?
Not directly. macOS negotiates the codec automatically with whatever the connected device supports, and there is no menu setting to force one. The real fix is choosing a device that supports AAC or aptX Low Latency, not adjusting a setting on the Mac.
Why is my TV or AV receiver's sound delayed even over HDMI?
Because the TV or receiver is processing the audio before it plays it, decoding surround formats or running its own sound processing, and that takes real, measurable time separate from anything the Mac is doing. Turning off unnecessary processing modes on the TV or receiver itself, not a Mac setting, is what reduces it.
Does combining a Bluetooth speaker into a Multi-Output Device make the lag worse?
Yes. A Multi-Output Device has to keep every device in the group playing in lockstep, so the whole group can only play as fast as its slowest member. If one of those devices is a Bluetooth speaker running SBC, every other device in the group, including a wired speaker with almost no delay of its own, waits for it.
Can Chorus fix Bluetooth or HDMI audio lag?
No. Those delays come from the Bluetooth codec and the TV or receiver's own processing, both outside any app's control. What Chorus can do is make it fast to drop a laggy device out of a group, or switch to a single low-latency output, with a keyboard shortcut, then switch back once you don't need everything playing together.
