Does HDMI 1.3 fix lip sync issues? - AVS Forum
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post #1 of 19 Old 07-14-2007, 09:00 AM - Thread Starter
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I recall reading months ago that one of the benefits of HDMI 1.3 is built in lip sync so that the equipment can automatically determine and set the delay for you - and as a result, no more lip sync issues. Is this true?

If that is true, does the display also need to be HDMI 1.3?

For instance I have the Toshiba XA2 HD DVD player which is HDMI 1.3. If I get a HDMI 1.3 capable receiver, but my projector is only HDMI 1.2, would I still get the benefits of the auto lip sync?

Logically speaking it seems like the projector would need to be 1.3 compliant as well because it would somehow need to support the feature so it could report back to the receiver what its processing delay time was so the receiver could adjust for it. Because otherwise how would the receiver know what type of delay was occurring as a result of the projector's video processing?

Thanks.
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post #2 of 19 Old 07-14-2007, 11:04 AM
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You are correct. The display also has to be HDMI V1.3 and also has to actually implement the optional feature of reporting back its video processing delay to the audio processing hardware. [NOTE 1: If your receiver does video processing for you, then the bulk of the video processing delay may actually exist inside the receiver itself, and the receiver may have already corrected for it. NOTE 2: Auto lip-sync correction actually first became part of the HDMI spec in HDMI V1.2a, but no manufacturers bothered to do anything with it. So technically all you need is V1.2a, but good luck finding stuff that implements this option.]

However you can easily achieve the same effect manually using a receiver that has a manual lip-sync adjustment and a calibration DVD such as Digital Video Essentials (DVE).

The calibration DVD has a simple to use audio timing test chart -- a sweeping clock hand that makes a beep each time it passes 12. Play that chart and adjust the audio delay manually until you are happy with the sync. The amount of adjustment you need may very well be quite small or even 0. This is normal. This is a one time adjustment you make during setup. The video processing time in your display and the audio delay needed in your receiver to compensate for it will not vary.

But note that this manual technique, and also the optional automatic feature of HDMI V1.3, can not correct for problems that ALREADY exist in the source content before it reaches you, nor for bugs in your source devices that cause them to generate varying amounts of sync error.

And in reality, what most people are seeing when they see audio sync problems has nothing whatsoever to do with video processing time in their equipment, but is instead one of those two other problems. Cable and Satellite TV services are often the culprit, and have even been known to send out programs where the video is AHEAD of the audio -- so that adding any audio delay would just make things worse. Again, automatic lip-sync correction in HDMI V1.3 doesn't try to address this common problem.

And some buggy DVD players have been known to produce varying sync errors even during the playing of a single disc! [Check for a firmware upgrade from the DVD player maker.]

Neither automatic nor manual lip-sync adjustment helps very much with this sort of stuff. There's no particular good answer to dealing with bad source content or buggy source devices. Trying to adjust lip-sync delay on the fly to compensate is usually too annoying. And sometimes the errors will even exceed the range of adjustment offered in your receiver (video ahead of audio or video way too far behind audio).

See the "Why you don't need HDMI V1.3" sticky thread at the top of this forum.
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Anthem D2/D2v/AVM50/AVM50v/ARC1 tweaking guide. -- Need personal consultation/training? PM me!
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post #3 of 19 Old 09-14-2007, 10:47 AM - Thread Starter
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Thanks Bob - very helpful and informative! Will there be a way to tell whether a display implements the auto-lip sync compensation feature? Or will we have to rely on the manufacturer to explicitly state so.

Has anyone had experience using a HDMI 1.3 receiver with the auto-lip sync compensation feature along with a display that supports it? How well does it work? Does the AVR give you feedback of any kind to let you know that it has engaged auto-lip sync?
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post #4 of 19 Old 09-14-2007, 10:57 AM
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Zero lip sync. My Denon is 1.3 and so is my PS3. It's going to my projector through a 35ft cable and there is no lip sync adjustment. This is the first time I've seen this. Usually with other receivers, it's set at 60ms or I could hear the audio is coming too early.

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post #5 of 19 Old 09-14-2007, 11:16 AM
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Quote:
Originally Posted by Bob Pariseau View Post

And in reality, what most people are seeing when they see audio sync problems has nothing whatsoever to do with video processing time in their equipment, but is instead one of those two other problems. Cable and Satellite TV services are often the culprit, and have even been known to send out programs where the video is AHEAD of the audio -- so that adding any audio delay would just make things worse. Again, automatic lip-sync correction in HDMI V1.3 doesn't try to address this common problem.


In today's HD broadcasting/distributions systems of uplink & downlinks, moving the HD video is the culprit.. This requires significant bandwidth & speed compared to audio, and often lags.. This is compounded by the on-board video processing within the source, AVR or even video display which all contribute to this issue.

Just my $.02 worth..
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post #6 of 19 Old 09-14-2007, 11:45 AM - Thread Starter
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Quote:
Originally Posted by eightninesuited View Post

Zero lip sync. My Denon is 1.3 and so is my PS3. It's going to my projector through a 35ft cable and there is no lip sync adjustment. This is the first time I've seen this. Usually with other receivers, it's set at 60ms or I could hear the audio is coming too early.

I'm not sure if you are saying you have zero lip-sync (as in no lip sync issue) or if you are saying you have zero lip sync adjustment (as in the promised lip sync auto correction features is not working or non-existent)? Can you clarify which one you are speaking of?

Also what is your display and is it HDMI 1.3 compliant?
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post #7 of 19 Old 07-16-2008, 01:20 PM
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Research at Stanford University proved lip-sync error present in every home theater is undermining "our impression of the characters and story". And, contrary to popular belief, HDMI 1.3 does not really correct it.

Read the Stanford research (at www.felston.com/research or at www.Pixelinstruments.tv )and see how this impossibility of nature causes its negative impact even when you don't consciously notice it.

Viewers described the characters as "less persuasive", "more agitated", etc. – the same way we describe people who don't look us in the eye. I'll make the connection below.

In the real world you can't hear a sound before you see the action that created it. To the contrary, you will see the action – lip movement for example – and the sound will follow, delayed about 1 millisecond per foot the sound travels.

This space time relationship is violated in home theaters when delays from video and audio processing allow sound to arrive too soon or too late. Since we can't reconcile this physical impossibility, we avoid it, subliminally looking away from the characters' lips and faces. This hides the problem but causes the same negative impression as if the characters "were not looking us in the eye".

Most A/V receivers can add a fixed audio delay to offset a display's video delay but that doesn't solve the problem since lip-sync error is not fixed. It often varies more from program to program and DVD to DVD than its fixed component coming from your display.

And, this widely misunderstood "automatic lip-sync correction" feature of HDMI 1.3 does nothing more than "automatically" set a fixed delay as instructed by the display during the EDID handshaking. Ironically, rather than "correcting lip-sync", this can actually make it "worse" when audio arrives delayed.

The only way to really correct lip-sync and eliminate its disruption is to fine tune a variable delay while focusing on the lips. Alchemy, Felston and Primare make remote controlled digital audio delays which allow on-the-fly adjustment without image disturbance for this purpose. I use Felston's third generation DD740.

When doing that your display's video delay becomes an asset and can offset audio that arrives delayed which sometimes does happen. As another member pointed out the largest component of lip-sync error often comes from video (and sometimes audio) delays within the broadcast chain or even DVD encoding and "automatic lip-sync correction" is actually impossible since there is no watermark in the video and audio to define when it was "ever" in sync.

I use a Felston DD740 and spend a few seconds at the start of every program and DVD focusing on the lips and tweaking lip-sync until it is perfect. That's the only way to eliminate the subliminal disruption documented at Stanford since they clearly point out that while most people won't notice 40 ms lip-sync error its negative impact on viewer perception is still there.

To eliminate it you have to force yourself to look at the lips because our natural tendency is to look away to avoid this impossibility of nature. In reality HDMI 1.3's misnamed feature (as well as the fixed delay in most AV receivers) does us a disservice since it helps mask the problem (making it easier for us to avoid) but usually leaves over 40 ms uncorrected and still undermining our impression of the characters and story. What could be worse? Isn't that what cinema is all about - our impression of the characters and story?
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post #8 of 19 Old 07-16-2008, 01:28 PM
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Excellent post nexsen. Thanks for taking the time to write it.
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post #9 of 19 Old 07-16-2008, 01:48 PM
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Assuming the synch issues orignate in our own systems, I keep thinking that our systems should not have them if the devices are implemented correctly.

Is the HDMI lip synch solution and the receiver video lag solution a bandage over simplistic audio/video processing software?

It would seem that a TV that has to process video should be "stamping" the audio associated with a frame number and buffering it up. It should not start playing audio associated with each frame until that frame is made availble to the display circuit.

As for receivers, as long as your source is digital and outputting HDMI there should be little need to much with the HDMI packets. One assumes that moving to the future devices will send out at least 480p of neatly packetized HDMI audio/video and only the TV should need to deal with any internal synching issues.

My XBox 360 seems to be perfectly synched up when playing Guitar Hero. My DVD player seemed to have some serious synching issues, I expect it's a flaw in it's firmware.

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post #10 of 19 Old 07-18-2008, 08:57 PM
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The only component of lip-sync error that usually originates in our home theater equipment is a fixed video delay caused by the digital video processing within the display. A fixed audio delay can cancel that fixed video delay but the variable component of lip-sync error will still be there.

That variable component is already in the source material when it arrives (via broadcast or even DVD's) and originates as tiny sync errors creep in during production and broadcast as well as DVD encoding. A few ms here and there but they are cumulative and can exceed the error caused by a display.

The problem is that there is no watermark in the video and audio to define when they were ever in sync most of the time. Sync errors can actually start with image capture as some digital cameras create an error equivalent to what progressive scan conversion causes.

That is, just as progressive scan conversion must wait 16 ms (or 20 for PAL) after receiving line 1 before line 2 comes along, some cameras CCD arrays do the same thing injecting a similar video delay and allowing the audio to get ahead. I saw this in an interview once where the 16 ms error came and went as they switched back and forth between the two cameras. When that happens there is no way to practically correct it. With my DD740 I "could" set two presets 16 ms apart and as the camera switched from interviewer to interviewee I could press the appropriate preset button but that would be far too tedious and perhaps useful only when recording the corrected output.

Often audio is recorded separately on a DAT with time code but that too can introduce error since they normally use a slate or clapper board which displays the time code. My question when viweing that frame - basically a snap shot 33 to 40 ms in duration (NTSC or PAL) - is "where during that interval did the clparrer strike producing the sound? Obviously somewhere during the 33 to 40 ms interval but is it in the middle, beginning or end? Realistically I don't thaink that can hope to get lip-sync to be much better than within a field which may seem perfectly fine if that were the "only" source of error and not just the first one.

But most errors creep in during production and broadcast when digital video effects delay the video and the compensating audio delay doesn't exactly match. If any error is created it can not be detected downstream since there is no watermark most of the time.

Watermarks are added at some points such as in MPEG compression and transmission and they are used to keep the video and audio streams in-sync during that process or transmission but the problem is that they must assume that the video and audio input streams were in-sync when they received them and that's normally not the case.

There is a good white paper on the technical details page of LipFix.com written by a VP of a television broadcaster whose company does an outstanding job of managing lip-sync error within their stations (measuring video delay at every step and adding an offsetting audio delay) but he concludes the article (a white paper written for the SMPTE committee on lip-sync) by saying that they can only hope to "add no more lip-sync error" since the feeds his stations receive from the major networks are "already out of sync" when they receive them and there is no way to automatically correct it.

Until a watermark is paced in the video and audio by the content producer and maintained continuously there will be no way to automatically correct lip-sync error and get it below the value Stanford proved still causes the negative impact on our perception of the characters.

If you read the Stanford reserach report you wiull see they only tested down to a value most people did not notice (41..25 ms I think it was) and reported the same negative mpact on perception was prestent but I am interested in how far below that you'd have to go before the negative impact would vanish.

I suspect the negative impact may remain as long as our brains can detect the impossibility and cause us to look away to avoid it and susc a study could probably be done with eye tracking technology as is currently used to track where you look on webpages.

It amazes me how many programs and DVD's nowadays actually arrive with audio delayed instead of ahead as was normally the problem. Luckily with a digital audio delay in conjunction with the video delay inherent in modern flat screen displays you can effectively delay both video and audio with an audio delay. That is you effectively "go negative" and use your display's video delay to cancel audio arriving delayed when you decrease the audio delay below the value required to offset your displays video delay.

An example would be Denzel Washington's "Inside Man" which has about 40 ms "audio delay". If your display has 60 ms video delay you would normally need to add 60 ms audio delay to correct lip-sync if the arriving signal had no error so for this DVD you would decrease the audio delay to 20 ms which uses 40 ms of your display's video delay to cancel the 40 ms of audio delay in that DVD source.

That is an example of a case where HDMI 1.3's auto lip-sync correction will actually make lip-sync worse than if you had done nothing at all. That is, it would add the same 60 ms audio delay preserving the 40 ms audio delay in what you are watching whereas doing nothing at all would have produced only 20 ms error. So much for "automatic lip-sync correction".
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post #11 of 19 Old 05-28-2011, 08:30 PM
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Thank you nexsen for the information that you have provided but actually the biggest lip synch problems are indeed originating from our home theatre equipment.

People who are coming to forums like this are not interested in lip synch errors in the source material ranging from production to broadcasting issues. The problem that so many are wanting to understand and solve is actually very simple. The problem is that the HDTVs nowadays are delaying the video and the audio coming out of our trusty old DD 5.1 receivers is not being delayed. This is the problem that is concerning most people. However bringing up issues with source material is only unnecessarily complicating the issue and not providing an answer for the one issue that most people want an answer for.

I can say this because most people are quite happy with the lip sync if they would connect an old CRT TV to the DVD/bluray player (just not with the tiny horrible picture). The lip synch issue did not become such a widely recognised problem until the arrival of the HDTVs, so it is clearly not the audio/video synchronisation of the source material that is bothering everyone.

I for one am faced with the issue with a new HDTV and a pre-HDMI receiver, which I do not want to replace. I am trying to find a good solution to this problem and reading posts about how the source material is anyway often not in sync is simply not helping. I don't want to fix the source material. If the source material needs fixing, then it is substandard and I don't want to watch it. I want to fix my system that has an inherent problem.

In a similar way, if my TV had a fault and was producing a bad picture, I cannot blame the broadcaster for the bad picture even if it is known that the broadcaster may on occasion transmit bad pictures. It is simply not the source material that is at fault.

By the way, in my opinion it's not really lip synch that is the real problem. It's not ideal if the lip movements don't match exactly but it's not really tragic either. What's really annoying are things like hearing the sound of a door slam when the door is still closing or the sound of a ball bouncing off the ground when the ball hasn't hit it yet, etc.

I have been looking at a "4-Port HDMI Input to HDMI + Optical/Coaxial Audio Output Converter" (model number U2000) from dealextreme but no one can say if it delays the audio by the amount that the TV delays the video. If this box would do the delay specified by the TV then I'd be happier with this than with a manually configured delay box which would probably always wind up with the wrong delay setting.

Does anyone have any recommendations?
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post #12 of 19 Old 06-10-2011, 05:11 PM
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Quote:
Originally Posted by nexsen View Post

An example would be Denzel Washington's "Inside Man" which has about 40 ms "audio delay". .... That is an example of a case where HDMI 1.3's auto lip-sync correction will actually make lip-sync worse than if you had done nothing at all. That is, it would add the same 60 ms audio delay preserving the 40 ms audio delay in what you are watching whereas doing nothing at all would have produced only 20 ms error. So much for "automatic lip-sync correction".

This reasoning is backwards. Basically you're saying that the automatic lip-sync correction is flawed because it only compensates for the system's inherent lip-sync issues and not for the garbage going into it. As far as I'm concerned, garbage in = garbage out. I think it is unreasonable to expect more from a home theatre system. We absolutely should not have to put up with quality in = garbage out, which is what you get without the automatic (or manual) lip-sync correction.

It might be pointless writing all this on a stale thread but this thread came up in google so I guess it still has relevance.

Again, are there recommendations for consumers with a new HDTV and an older pre-HDMI DD-5.1 receiver with optical audio connection?
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post #13 of 19 Old 08-12-2011, 11:32 AM
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incrediball, I also recently upgraded my old SD TV with an HD TV, which introduced video processing delays causing my audio (going to my non-HDMI capable audio equipment) to be ahead of my video, just like yours.

I was able to solve my problem by running my optical audio out from my TV to the audio receiver, rather than running the optical audio directly from my satellite receiver to the audio receiver.

Your TV may not have an optical audio output, in which case you'd lose your digital 5.1 signal, and be reduced to just Left/Right analog audio, but at least it would be in sync.
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post #14 of 19 Old 08-15-2011, 04:36 AM
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Quote:
Originally Posted by kmatzdorf View Post

incrediball, I also recently upgraded my old SD TV with an HD TV, which introduced video processing delays causing my audio (going to my non-HDMI capable audio equipment) to be ahead of my video, just like yours.

I was able to solve my problem by running my optical audio out from my TV to the audio receiver, rather than running the optical audio directly from my satellite receiver to the audio receiver.

Your TV may not have an optical audio output, in which case you'd lose your digital 5.1 signal, and be reduced to just Left/Right analog audio, but at least it would be in sync.

I believe the issue is more centered with the broadcasters than the equipment. The proof of that is the variable delays we witness. 98% of the channels may have perfect lip synch, but 2% may not. This shows the source (typical set top box), is in synch with the display, but a few offending channels are not. This certainly seems to point the finger toward the broadcaster on those offending channels.
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post #15 of 19 Old 03-30-2012, 06:02 PM
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Quote:
Originally Posted by kmatzdorf View Post

incrediball, I also recently upgraded my old SD TV with an HD TV, which introduced video processing delays causing my audio (going to my non-HDMI capable audio equipment) to be ahead of my video, just like yours. I was able to solve my problem by running my optical audio out from my TV to the audio receiver, rather than running the optical audio directly from my satellite receiver to the audio receiver. Your TV may not have an optical audio output, in which case you'd lose your digital 5.1 signal, and be reduced to just Left/Right analog audio, but at least it would be in sync.

My TV does have an optical out which I use when watching TV or a file being played from a USB stick plugged into the TV. However when watching DVDs and blurays the 5.1 signal is lost and it is only stereo which is for me even more unacceptable than the sync issues.

Quote:
Originally Posted by Ken Ross View Post

I believe the issue is more centered with the broadcasters than the equipment. The proof of that is the variable delays we witness. 98% of the channels may have perfect lip synch, but 2% may not. This shows the source (typical set top box), is in synch with the display, but a few offending channels are not. This certainly seems to point the finger toward the broadcaster on those offending channels.

Wrong.

As I said earlier, I don't care less about substandard source material. If they can't get their act together then I don't watch it.

Unless you have experienced watching a new HDTV with audio coming out of a separately fed amplifier then you don't know what we're talking about. As I said earlier, this set up was quite acceptable when we had CRT TVs because the TVs displayed the picture immediately. Now TVs have to process the video data and so the image lags behind the audio coming out of the separate audio system which is still immediately outputting the sound.

There are expensive devices available which allow you to manually delay the audio so that it matches the TV's processing delay. I even work for a company that designs and builds multi-room amplifiers that offer this as one of their features but unfortunately they're darn expensive and they only do stereo. Besides I would like a smarter solution than a manual delay because the TV is not going to always have the same amount of processing for every picture format, resolution, etc and I'll always be wondering if it is set correctly and will be critically looking for sync issues which will ruin what should be entertainment and relaxation.
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post #16 of 19 Old 07-05-2012, 10:17 AM
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Have i got this right?
A BlueRay player gets a best effort one time audio delay timing from the HDTV
The blue-ray player then delays sending the audio to the HDTV over the HDMI cable..
BlueRay player is delaying it's audio and then HDTV is delaying the picture, hopefully by roughly the same amount so the two are roughly more or less back in sync. smile.gif

SO

if the a blue-ray is delaying the audio why is spdif audio out not affected?
if the Blue-ray player delayed then spdif audio out by the same amount us non-hdmi AV receivers set-ups would also be benefit from the hdmi 1.3 lip sync.
I'd be happy.

Does it just not work like this?
Does anyone know if any source device do this?

Maybe it's just time for a new receiver. shame as the one I have sounds just fine.
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post #17 of 19 Old 07-05-2012, 03:15 PM
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Just to be sure I'm answering the right question - all the "automatic lip-sync correction" feature of HDMI 1.3 does is "automatically" set an audio delay which will remain fixed and won't change at all as lip-sync error changes from program to program, This is basically the same as most non HDMI Av receivers have done for years "except" you have to go into a menu and set that fixed audio delay manually "one time". The feture saves you those few minutes - however long it would have taken you to set a delay of say "100 ms".

The audio delay it sets should offset the video delay of the display and solve the problem "if" the source material were in sync - but it seldom is.

This feature is "optional" and not implemented in all devices. For example I don't recall most BluRay players having the ability to delay audio. Normally that's done in an AV receiver. If your BluRay player went into an AV receiver and its output went to your display for eample.

When they first connect there is an EDID session (much like plug and play for computers) during which the display (the sink) tells the source (the AV receiver) all its "specs" It's video resolution, its audio capabilities, etc and part of that include two values for its video delay: one for interlaced video and one for progressive. They will be about 16 ms different.. My old Toshiba for example had 100 ms and 116 ms video latency values. Depending upon the negotiated video format either 100 or 116 ms audio delay would be set after that EDID session.

But this doesn't "really" correct lip-sync completely because there is lip-sync error in the content being received (via broadcasts especially) and correcting for that requires adjusting for more or less audio delay as the lip-sync error changes between programs.

Unfortunately most receivers imbed their audio delay setting in a set-up menu making it impractical to adjust while watching the programming due to all the menus you have to go through overlaying the image. For those who want to totally correct lip-sync a dedicated audio delay is usually required and with it they can change the delay via remote control without disrupting what everyone is watching. Such digital audio delays are made by Alchemy2, Felston and Primare. They require you use s/pdif (optical or coax) audio connections because they must intercept the audio to delay it.
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post #18 of 19 Old 07-06-2012, 11:34 AM
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Here's a review of the 3 digital audio delay boxes I mentioned: http://audaud.com/2007/07/3-lip-sync-error-delay-units/
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post #19 of 19 Old 03-17-2014, 01:25 PM
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I realize this is an old thread but even more relevant as image size gets larger causing larger video delays and consequrntly greater lip-sync error.

My reason for this post is to mention a new lip-sync correction feature announced for HDMI 2.0. Of coures HDMI 2.0 isn't out yet but the feature is called "dynamic lip-sync correction". It allows an HDMI 2.0 TV to send audio delay values to an AV receiver (or other equipment which might have the ability to delay audio) as its video processing delay changes via CEC. This is supposed to address the deficiencies of the HDMI 1.3 automatic lip sync correction which only had two delay values - one for interlaced and one for progressive regardless of resolution. Since a change form 720 to 1080 (regardless of interlaced status) could cause a 10 ms video processing difference the current HDMI automatic lip-sync correction can't make that change and lip sync will be off at least 10 ms but the new HDMI 2.0 feature woukld allow the TV to send a new delay request to the AV receiver when the content it was displaying changed from 720 to 1080.

That would certainly better but the bigger question is: Will TV manufacturers implement it? Few have even implemented the simplistic 2 value scheme of HDMI 1.3. My old Toshiba did implement it and had 100 ms latency for progressive and 116 ms for interlaced but neither of my two new Samsungs or Vizio's have any latency values at all.

And can anybody tell me how to find this out "before" buying a TV? I can't find it in any spec or in any product review! Everyone seems to assume if it's HDMI 1.3 or above it must have automatic lip sync correction but that's more often NOT the case. And as long as it is an optional feature I doubt many of these manufacturers will implement the far more complex HDMI 2.0 feature where they will be expected to send a different delay value for every combination of resolution, frame rate and interlaced status that can be displayed.
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