What is sound sync on LG TVs
LG TVs have a Sound Sync setting, this is a software correction for synchronizing picture and sound. For example, maybe you noticed, when playing a video, the movement of the lips of the actors does not coincide with the sound. Here Sound Sync should synchronize video and sound.
How LG sound sync works
There are several modes of operation, of course you can turn off synchronization or enable by selecting the appropriate mode.
- TV speaker
- External speaker Optical / HDMI ARC
- LG Sound sync (Optical)
- LG Sound sync (Wireless)
Why there is a desync of video and sound. The whole reason is the need for additional sound processing. Yes, this is a millisecond in time, but in the end it can be noticeable.
TV speaker
For example, how does the TV work when receiving video and outputting sound to the TV speakers. Receiving a signal by a digital receiver or via HDMI decoding separation of video and sound. The video stream enters the screen, and the sound to the speakers, in this case, almost everything happens synchronously.
External speaker audio transfer via HDMI reverse channel or optics
With this connection, the sound undergoes additional processing, the audio stream is sent not to the speakers, but is additionally encoded for transmission either through optics or HDMI. On an external device, the audio stream is decoded, amplified, and fed to the speakers. This takes some time. When this mode is turned on, the average delay time is taken.
LG Sound sync (Optical)
The same only audio processing time is calculated only for optics.
LG Sound sync (Wireless)
Audio signal processing time is calculated only for optics.
How LG Sound Sync works – because for each type of audio transmission, a certain time is set to process the audio stream. As a result, for synchronization, the video signal is delayed for the time necessary for processing the sound. This is how synchronization happens. But since devices are evolving every year, as some users notice, even turning on synchronization does not help to precisely match video and sound.
LG sound sync(optical): Is selected, and I have an optical cable from my tv to an A/D converter. The converter has a headphone output. I get audio from the tv to the headphones just fine but it is at a steady level. The volume control will not adjust the volume level. When I select Internal speaker + LG sound sync(optical) I get sound to the internal speaker but nothing from the optical output. This all points to a problem with the tv. What are your thoughts?
No, that’s correct, when you select the optical audio output, the TV speakers are automatically turned off so as not to cause interference. The sound must be controlled on your audio receiver. The TV transmits the sound as is without any processing via the optical output to the audio converter