When watching TV, you may find that sometimes audio and video do not match. The audio soundtrack may be slightly ahead of the corresponding image. When this happens, watching a cable/satellite/streaming program or DVD, Blu-ray or Ultra HD Blu-ray video disc on an HD TV or Ultra HD video projector in 4K high resolution can lead to disappointment. This is especially noticeable in close-up images of talking people ( thus the term «lip-sync» ). It’s like watching a badly dubbed foreign movie.
This issue can occur with TVs from various manufacturers, including but not limited to LG, Samsung, Panasonic, Sony, and Vizio TVs.
What causes audio/video sync issues?
The main reason for lip sync issues is that audio can be processed much faster than video, especially video high definition or 4K video . HD and 4K videos take up a lot of space. As a result, processing takes longer than standard definition audio or video.
If your TV, video projector, or home theater receiver is set to handle a large amount of video for the input signal (for example, upscaling from standard definition to 720p, 1080i, 1080p or even 4K ), the audio and video may become out of sync with the audio arriving before the video (or vice versa).
Check if the issue is related to a specific cable/satellite or streaming software or channel. Although annoying, the problem may not be at your end. This may be a temporary or chronic issue with a particular content provider. If you suspect this is the case, contact them for help or alert them to the problem.
Audio/video timing adjustment tools
Depending on your TV, home theater receiver, or soundbar, there may be tools or other steps you can take to help you manage AV sync issues.
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Turn off all video processing options on your TV, such as movement improvement video noise reduction and other image enhancement features.
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If you have a home theater that does video processing tasks, try the same procedure; You can add more delay by adjusting the video processing on both the TV and the home theater receiver.
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If changing the above settings corrects the situation, add each processing function back until the audio and video are in sync again. You can use this as your lip sync reference point.
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If the video processing function of the TV or home theater receiver does not work, or you need to enable these functions, check the settings available in the operation menu of the TV, home theater receiver and source components. Look for terms like Audio Sync , Audio Delay and Lip Sync . Some soundbar systems also have a variation of this feature.
Regardless of the terms used, all of these tools offer settings that slow down or delay the arrival of the audio signal so that the image on the screen and the audio track match. Settings typically range from 10ms to 100ms, and sometimes up to 240ms (millisecond = 1/1000th of a second).
In some cases, the audio delay can be offered in both positive and negative terms in case the video is ahead of the audio. Although milliseconds seem tiny, a 100ms change in audio and video timing can be very noticeable.
If you are using a home theater receiver with audio return channel function via HDMI connection you may need to adjust for automatic or manual AV sync correction. If so, try both options and see which one gives the most consistent correction result.
If your TV and home theater receiver (or soundbar) have eARC (Enhanced Audio Return Channel) lip sync should be performed automatically between the two devices.
If the audio/video sync issue is related to only one source (such as a Blu-ray/Ultra HD Blu-ray player, media streamer, or cable/satellite TV), check the audio/video sync settings on those devices that you can retrieve benefit.
Possible audio / video connection solutions
If the provided settings and other tools do not solve the problem, you can also try changing the connection settings.