HDMI Auto Lip Sync – Why Doesn’t It Work?
It is frustrating when a feature is designed to fix a particular problem but doesn’t. Take HDMI Auto Lip Sync. It is clearly intended to fix any lip sync issues you have in your system. More often than not, if you have lip sync issues, HDMI Auto Lip Sync doesn’t work to fix them. Why? Or, more importantly, what can you do to actually fix the problem? Let’s discuss.
What is HDMI Auto Lip Sync?
It idea behind HDMI Auto Lip Sync is simple. As your audio and video travel from your source, through your AV receiver, and into your TV, delays can be added. Processing the audio and video can take time. Not a lot, but some. That time can create a disconnect between the audio and the video. This manifests most obviously as the voices become out of sync with the movement of the character’s lips on the screen. Most commonly, the video is slightly delayed as it takes more time to process than the audio.
HDMI Auto Lip Sync is designed so that all the devices in the signal chain that are connected through HDMI cables communicate with each other. Any delays will be automatically detected and corrected. Sounds great, no? No! Because HDMI Auto Lip Sync rarely works.
Why Doesn’t it Work?
HDMI has promised many wonderful features. Some of them actually work. This is not one of them. The main reason why is that most HDMI features are optional. This means that the HDMI connection is capable of doing something (like HDMI Auto Lip Sync), but it is up to each manufacturer to enable it so that it works. If just one of your devices in your signal chain doesn’t have HDMI Auto Lip Sync, or if one of them doesn’t have it implemented properly, it will not function as intended.
On top of that, adding an AV receiver to the mix seems to be the main culprit. If you have used HDMI Auto Lip Sync successfully, then you are probably using a system without a receiver. A TV and soundbar, for example, with a couple of sources plugged into one or both. That type of system tends to find that HDMI Auto Lip Sync makes things better.
How to Fix Your Lip Sync Issue?
As with everything HDMI, if you are having lip sync issues in your system, find Auto Lip Sync in each and every device in your system and turn it off (or disable it). Most of the time (especially if you are using an AV receiver) turning off HDMI Auto Lip Sync will work to fix your problem. Yes, it’s counterintuitive, but it works.
If you don’t have an AV receiver in the mix, and turning off HDMI Auto Lip Sync didn’t work, then try making sure it is on for every device. If that also doesn’t work, then switch where your sources connected if possible. For example, if all your sources are connected to your TV, try switching them to your soundbar (or vice versa).
Lastly, many devices have lip sync adjustments that can be controlled manually. This is the option of last resort as it often only works for a single device and will need to be changed for each source. There is usually a slider or numerical control for lip sync. These are in milliseconds so you don’t want to go one at a time. We usually adjust by 10 to 15 milliseconds (which is about as much as you can notice). Adjust, test it out, and repeat until the lips and the voices match.