Originally Posted by sheshechic
Just to be sure... did you try the Bravia Sync settings in the tv?
Actually, after even more testing and hair pulling I've decided that this has nothing to do with my soundbar. The soundbar itself adds a minuscule amount of audio delay, as tested by turning off HDMI control and hearing audio from both the internal speakers and the soundbar at the same time. I've tried this with my PS4 Pro, the native apps, and my cable STB. In all cases, the soundbar is not to blame, but since it adds a tiny bit of latency it does in some cases make the problem more noticeable (perhaps elevating the latency just past some minimum detectable threshold for us humans).
Instead, it really does seem to be an issue with how long it takes the TV to process/pass through incoming audio signals. For now I have connected my PS4 Pro directly to the soundbar via optical, but this is a little annoying since I need to manually change the input source on the soundbar whenever I switch to the PS4 because if I don't, the TV's optical or ARC connected to the soundbar takes over (can I short circuit that path somehow?). In any event, zero audio latency with this approach.
Interestingly, though, with my old setup (PS4 -> HDMI -> TV), the delay (which, recall, was actually present even when using the TV's built-in speakers) was pretty much unnoticeable when I forced my PS4 to output 2-channel PCM. But when outputting 5.1 DTS or Dolby (bitstream) to the TV from the PS4, the latency was about 100-150ms. What gives? Is this TV slow decoding certain audio formats?
Note that I do see lip sync issues via my set top box (STB -> HDMI -> TV) regardless of whether I ask U-verse to output in stereo or surround, so I don't think the issue is quite as simple as 2.0 good, 5.1 bad.
Turns out PS4 -> HDMI -> TV suffers from delayed audio regardless of the use of the soundbar. It also turns out that this delay is mitigated when the PS4 is forced to output 2.0 audio. However, 5.1 audio to the soundbar is not delayed when the PS4 is connected to it directly. This is therefore the TV's fault, not the PS4's or the soundbar's. Similar issues occur with my STB.