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Digital or Analog Lip-Sync device

JeanMiK

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Hi
I recently updated my TV system (for a bigger led screen), linked to my stereo hifi system.
For a better sound, I've always been linking my Internet box directly (via its Optical output) to a dac (Topping D50)
and my stereo amplifier.
It's always been working fine before, but I now discover that these recent TVs show a small delay between the image and the sound (due to the sophisticated image processing).
I tried and managed to cancel it with my Behringer Ultracurve pro DEQ2496 (a bit complicated when you want to simply watch TV), and found it was about 65 millisecond long.
(Of course there is another possibility to theoretically avoid this problem, linking my DAC to the optical output of the screen, but that output has unpredictable lags and short interrupts. Can not be used because of this.)
So, I did some research on the internet, and discovered that there are quite some small handy devices to cancel this commun issue ..............

This Felston device (quite expensive)
http://www.felston.com/dd740/
This analog devices
https://www.converters.tv/analog_audio/Left-Right-In-Out-Lip-Sync-Corrector/863.html
and a few other of this kind
This J.S. Technology Ltd device (I finally ordered this one)
http://www.js-technology.com/store/category.php?id_category=9
This RTI device
https://www.rticorp.com/adm-1-audio-delay-module.html
The Sescom digital device
https://www.sescom.com/products/view/product/productslug/ses-a-v-sync-av-lip-sync-corrector

Most of them have 20ms or 50ms adjusting steps, I think 20ms is acceptable according to what I found with the Behringer, 50ms way too much, 5ms or less would be best.

Do you know of serious technical reviews of these devices, or any of you having some experience with this issue ?
Thanks a lot

JMK
 

RayDunzl

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My new TV has adjustment for the optical output built in - 200ms range with 10ms steps.
 
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JeanMiK

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My new TV has adjustment for the optical output built in - 200ms range with 10ms steps.

Hi !
Mine also has it built in, but time to time lag problem - very much frustrating !
My Internet box is more efficient in extracting sound from the digital feed.

JMK
 
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JeanMiK

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Hi !
Mine also has it built in, but time to time lag problem - very much frustrating !
My Internet box is more efficient in extracting sound from the digital feed.

JMK

..... and this JS Tech has 5ms steps.

One question remains, how transparent is this device .... ?

JMK
 

somebodyelse

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The digital ones ought to be transparent - they're just reading the data into a buffer and reading it out after however many ms. They might have some jitter, but probably no worse than the TV, and a decent DAC these days will be more or less immune anyway.
 
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JeanMiK

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The digital ones ought to be transparent - they're just reading the data into a buffer and reading it out after however many ms. They might have some jitter, but probably no worse than the TV, and a decent DAC these days will be more or less immune anyway.

Ok, thanks. According to what I've read here and there from people using the tv's optical output (to feed sound bars or other external devices) and complaining on lag and out of sync, the fault is on the tv for some reasons.
The only solution is to get the digital sound directly from the box. Then you won't have any issue.
Too bad this not well considered. Maybe "high end" tvs don't face this issue.

JMK
 

RayDunzl

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Does the adjustment go both ways?

I don't know that I have a source with known/expected sync/delay with which to experiment.

Looking now, it is 0-250ms, and I'm happy watching lips at 30ms delay at 10 feet, on a "broadcast" cable channel..
 
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JeanMiK

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I don't think so. You can only delay the sound, steps (10 available) are not documented.
This new TV is a LG 43UM7400plb.
Very likely 20ms steps.
But it's of no use. The audio you get from the tv's optical output is well synchronized, the issue is the lag and interruptions you get from time to time. Almost every minute when you start your tv, less frequently after some time, but very frustrating.
My only solution is to use the internet box's optical output, and delay it before my dac.

JMK
 

Soniclife

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I don't know that I have a source with known/expected sync/delay with which to experiment.

Looking now, it is 0-250ms, and I'm happy watching lips at 30ms delay at 10 feet, on a "broadcast" cable channel..
Shame, what I expected but, I hoped they would have added a frame buffer to enable the video to be delayed instead.

You can find test files online to get the sync correct, if it's bothering you, if you are happy I'd leave it alone.

Does anyone else think the brain adjusts over a period of time to make small sync errors seem OK.
 

Soniclife

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But it's of no use. The audio you get from the tv's optical output is well synchronized, the issue is the lag and interruptions you get from time to time. Almost every minute when you start your tv, less frequently after some time, but very frustrating.
Interruptions make it sound like something is broken. Does the sync wander around using the internal speakers?

If your cable box has HD and SD sources, and offers upscaling/conversion to HD all the time that might change things.
 
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JeanMiK

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Interruptions make it sound like something is broken. Does the sync wander around using the internal speakers?

If your cable box has HD and SD sources, and offers upscaling/conversion to HD all the time that might change things.

Checking the internal tv sound is the only thing I haven't done yet. I assume there is no issue, but I will check.
From what I understand, the sound data is mixed with the video in the HDMI feed.
And the best way to avoid problems in my setup (never experienced any lag or interruptions) with my box's optical output, is to use it instead of tv's (very likely not sophisticated and powerful enough).
I guess the tv board is busy enough dealing with image.....
JMK
 

Soniclife

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Checking the internal tv sound is the only thing I haven't done yet. I assume there is no issue, but I will check.
From what I understand, the sound data is mixed with the video in the HDMI feed.
And the best way to avoid problems in my setup (never experienced any lag or interruptions) with my box's optical output, is to use it instead of tv's (very likely not sophisticated and powerful enough).
I guess the tv board is busy enough dealing with image.....
JMK
Audio isn't an optional part of a TV, and audio processing isn't a hard thing to process, and will be done in a dedicated chip, it should just work. It could be the optical out hardware being bust.
 

ElNino

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I don't think so. You can only delay the sound, steps (10 available) are not documented.
This new TV is a LG 43UM7400plb.
Very likely 20ms steps.
But it's of no use. The audio you get from the tv's optical output is well synchronized, the issue is the lag and interruptions you get from time to time. Almost every minute when you start your tv, less frequently after some time, but very frustrating.

That's strange... I have nearly the same model (LG UM7300) and haven't had any issue with the optical output from the TV.
 
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JeanMiK

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That's strange... I have nearly the same model (LG UM7300) and haven't had any issue with the optical output from the TV.

Could be some compatibility issue between the optical tv's output and my topping d50?
I also own a topping dx7s and tried it: same issue.
The tv's optical output if set to pcm ok.
Ok, then I also have an old and simple matchbox like dac, I should try it.

Jmk
 

RayDunzl

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You can find test files online to get the sync correct, if it's bothering you, if you are happy I'd leave it alone.

I tried several YouTube tests (for whatever that's worth)

Alignment seems good at PC

Sending via HDMI to TV, it took all 250ms delay to look/sound correct.

Changing back to the cable broadcast, it looked way off. Readjusted using visual lips and voice.

So... ???

Anyway, the adjustment seems adequate for lips. A better test will be watching a drummer.

---

Using the TV's native YouTube app, and the same files, and the same setting as set for the cable broadcast, it looked fine.

---

Somewhere I remember reading that the eye takes 200ms longer than the ear to recognize some excitation... I'll see if I can find that again...


https://blog.medel.com/the-speed-of-hearing/ -- some random source

"Once a sound wave reaches your ear, your brain can recognize it in just 0.05 seconds. "

" It takes about 0.2 seconds for your brain to understand the light that reaches your eye. It also takes about 0.2 seconds for your brain to recognize something touching your hand or foot. "

Ear delay - 50ms
Eye delay - 200ms

So... Assuming perfect sync in the output of the video and the sound, at 10 feet

The sound would need to be delayed 140ms (eye/ear perception time difference less time from speaker to ear) to sync with the picture, in the consciousness.

(I'm ignoring the time it takes the image to travel 10 feet)

---

After performing a few "live" tests, making noise in the room at various distances, I think the ear/eye times are overruled by Bain processing to sound and sight together into a single unit.

I don't sense a delay in sound vs visual with a test up to 20 feet (20ms) so, exact sync probably isn't critical (to me)
 
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JeanMiK

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My new TV has adjustment for the optical output built in - 200ms range with 10ms steps.

Hi !
Mine also has it built in, but time to time lag problem - very much frustrating !
My Internet box is more efficient in extracting sound from the digital feed.

JMK
 
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JeanMiK

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I just received my J.S. Technology device : works fine, 5ms delay steps.
Very handy device, as you don't have to call the menus and subsubsub menus of the TV's setup
in order to fix sound delay if needed.

I've also checked the internal TV's sound system: no lag, no interuption whatsoever.
The optical output of this TV has a problem, for some reason.

JMK
 
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