Slashdot Mirror
Lip Sync Problems with New Digital Displays?
An anonymous reader writes "With all of the new digital TV displays flying out the door, its easy to to think that life is good on the road to high definition. But, as Audioholics reports today, cheaper displays are using inexpensive processors that result in video delays of up to 60 milliseconds (that's about 2 frames of video). This means that the video processing (deinterlacing, video scaling, etc) delays the picture so that the audio is out of sync. Add to this inherent delays in some LCD and plasma units and the problem can be more than a little noticeable. As of right now only a few manufacturers are building audio lip-sync delay into their products to compensate."
I was wondering why Ron Jeremy's tongue was trailing behind the licking sound.
Trolling is a art,
Really? Damn. I was beginning to wonder why everything on T.V. was a badly dubbed German show.
Now the lips in my old gozilla movies will be in sync! Deaf people everywhere are rejoycing!
so *that* explains the lip sync problems in those old kung fu flicks.
"As of right now only a few manufacturers are building audio lip-sync delay into their products to compensate."
So once again, another company is working around the problem instead of fixing it. This seems to be a bad trend in technology these days.
Work sucked, until it became unemployment, when it became slightly more tolerable. -Tet
"Let's Fight!"
<mouth keeps moving for several seconds>
Oh, wait. Those kung foo movies were always like that.
I only watch 1960's Italian westerns and old Godzilla movies. Who knows, it might actually help.
Their video source wouldn't happen to be a linux machine playing macromedia flash movies would it?
booo I say
Maybe the seismic charge explosions in the Star Wars EP2 asteroid chase will be in sync with this.
The audio delay should be user configurable. We could turn boring stuff into something that's really funny. Almost as good as playing the old VHS backwards!
The Erogenous Zone
no problem with syncing there.
I am the Alpha and the Omega-3
Perhaps if they could get the display lag to equal the audio lag, the problems would cancel each other out!
Video games depend on low latency between input (at the gamepad) and output (at the CRT and speakers). Video game systems manufactured for sale in the United States after 2006 will include some sort of digital TV output. These digital TV sets introduce a significant latency into the chain. So what will happen?
So what happens when the input format changes? i.e. Will the equipment freak out when 1080p is sent to it, and then the unit is forced to convert to 720p? Basically, I hope they compensate for the variety of signals out there if they can't fix the problem at the source.
I watched an old Kung Fu movie on one of these, and the words matched the lips!
So that means that a plasma TV is going to be 60 ms behind my neighbors old CRT TV? No thanks. I need my reality TV as it comes, not later than my friends...
...and it did nothing to fix What's up, Tiger Lily? Guess I'll have to wait for version 2.
how is it possible for a manufacturer to make a product and sell it when it is such a fundamental problem? what kind of quality standards are these manufacturers catering to? is it cheaper to produce and sell buggy hardware than it is to develop quality hardware and produce and sell it?
sorry for not being up on my TV technologies but i was planning on gettitng a DLP TV soon and was wondering if they were effected?
is there a way i can test in the store?
Will you really notice if the entire feed is delayed by a fraction of a second?
If the feed is coming from a video game console that's responding to live user input, I'll certainly notice llaagg. A delay of 60ms can spell the difference between a hit and a miss, adversely affecting game scores.
But, there is the delay from the sound traveling from the speaker to your ear (roughly 1 millisecond per foot of distance traveled). So one solution is simply to put the speakers about 60 feet away.
All is Number -Pythagoras.
Audio and Video processing happens asynchronously, so I don't know how you can avoid this. You can set a time limit, but then you will limit the amount of processing that can occur which sacrifices audio or video quality. I have a Panasonic 42" Plasma that does internal scaling. This is slower than doing Dolby Digital decoding. My Anthem AVM20 processor has an audio delay feature where now my audio and video are back in sync. Receivers are getting this feature so eventually it'll be commonplace.
Comment removed based on user account deletion
Is it even possible to do analog signal buffering, or will the signal be converted to digital to buffer it for a few milliseconds and then back to analog?
I suppose it is possible to do analog signal buffering now that I think about it. Some guitar AMPs have a delay feture, which I'm sure is all analog.
There's no reason to build expensive circuitry to correct the problem. You can use the laws of nature to resynch your video!
For a video lag of 60 milliseconds, you only need to step back 20.4174 meters from your TV before the speed of sound will correct the synchronization problem.
-3Suns
~~~~
The Revolution will be Slashdotted
I find that if I get ever so slightly drunk, the delay in my mental processing of the auditory information compensates nicely.
If the TV delays both the picture and the audio, then how would one compensate for the lag if a picture is being generated in real time on the same premises as the set, such as from a PlayStation family game console? Watch Sony introduce NoLagTV(tm) technology, in which video enhancement processing follows the raster, in order to sell more TVs to PS family console owners.
Buffering....
Buffering....
Buffering....
First Post!
Thanks for the news! I was about to return all those old Toho Studio "Godzilla" movies I bought for my new TV because none of the words matched the lip-movements. Now I know why!
Don't blame Durga. I voted for Centauri.
I'll have to take that Milli Vanili DVD back to the store.
Where does the school board find them and why do they keep sending them to ME?
The problem applies equally well to any other kind of video/audio synchronization that when out of whack will appear unnerving to the viewer; for example, gunshots; car explosions; doors slamming; the little high-tech bleeps made whenever something appears on a computer screen; the wet slapping sounds of pelvic trusts against sweaty, naked female hind parts; etc.
-dB
"It if was easy to do, we'd find someone cheaper than you to do it."
I already get annoyed by lipsync problems from broadcasts on digital cable tv, from delays introduced by the production studios employing special effects on the video, coding and decoding delays on the settop box and now tv. Nice.
What this means to most slashdot users:
The sexual moans will be a half-second or so off.
...or at least my future father-in-law did. My fiancee's parents recently bought a very nice Samsung HDTV system which had this problem. The audio was way out of synch with the video, and it was quite noticeable at times.
Samsung ended up sending someone to the house, and replacing a board in the TV with a newer model, and that seemed to fix the problem.
I don't understand why they couldn't have anticipated this problem before they shipped the TVs, though. Isn't that what QA is for?
You can accomplish anything you set your mind to. The impossible just takes a little longer.
It would seem to me that its not compensation, but good design to build a tv set where the video and audio are in synch.
Seems more like the somebody's out to lunch if they build a box that can't get it right.
The solution might be for the managers at BestBuy, CircuitCity and so on to send them back when the set up a demo unit and see/hear that it's all f''ked up
--robin
...Boycott Disney
A cheap ATI TV Wonder VE (Value Edition) - mono sound, and the tv gets out of sync.
I only use it for watching hockey, so it doesn't really matter.
The weird thing is that the tv card just passes the audio through to the sound card (a built-in on the MB).
when I turned on the TV and saw Britney Spears in concert. But then I realized it wasn't my TV, she's just really bad at lip syncing.
Ron Jeremy... FoodTV... "Informative"... LMAO!
Some receivers like the Denon 3802 and upwards, are aware of these issues. They allow you to dial in delay so that you can sync with TV.
...
Just my 2 cents
...you can just view them from sixty feet away and the video delay will exactly compensate for the speed-of-sound delay. No problem.
And if you can afford one, you probably have a living room that big.
"How to Do Nothing," kids activities, back in print!
I frequently see audio delays on HDTV feeds being displayed on my DLP projector. Change the channel (to another station broadcasting at the same resolution), and the problem goes away.
It's either my crappy Scientific Atlanta HDTV receiver or the feed itself.
I really have doubts about this article.
get nemulator
Any bets that they're just trying to build in delays to prevent more 'wardrobe malfunction' fiascos?
:)
My hunch is that they delayed the video on purpose, but forgot to touch the audio.
You can accomplish anything you set your mind to. The impossible just takes a little longer.
Beyond the great video resolution of HDTV, it also supports Dolby Digital 5.1 surround sound. So, most people use their stereo receiver for the audio from HDTV broadcasts.
I have a macro set up on my remote, so when I turn the TV on, it automatically turns my receiver on & switches to the right input. I haven't used the speakers in my TV in 3 years, so I'm not sure if it has a lip sync problem or not (probably not, because it supports all the ATSC formats natively.. it doesn't need to do the extra processing which apparently causes the problem).
Digital Light Processing is based on a micromirror array that turns each colored pixel on and off a few thousand times per second. Such pulse-width modulation responds more quickly to pixel value changes than LCD ever could.
The old way was to read in a frame into memory. An other HW block or processor would perform the next operation, by reading that frame, process it and store it into memory again. The whole chain could be quite long.
This was not really a problem, they thought, because the audio was processed at the same time, and the delay was under full control of the soft and hardware.
until someone tried to use an external audio path...
As far as I know, they solved the problem, and the delay is minimal. And non existant if you route the audio over the same processor.
I've noticed it on regular TV lately.. its hard to catch, but its there..
Seems to have started once my cable company went to digital...
---- Booth was a patriot ----
Kind of like taking too much cough medicine before a job interview.
My Sony Receiver (didn't see that coming, did you) has the same feature set as described whereby I can "dial in" a value and change latency in the form of changing the distance from speakers to center of the room.
Oh, and...
CHARLIE MURPHY!!!!!
If anyone wants to see the real thing in action, just tune in to the Britney Spears concert that has been airing on ShowtimeHD. Her lips are definately out-of-sync with the music.
I was recently going through a list of I2C chips to mess around with on my BASIC Stamp. (One of the areas where the I2C protocol had some measure of success was in television.) I came across a chip, I want to say from Philips themselves, that could be used to introduce a sound delay to allow the video to be better sync'd to the video.
I was working on a video conference system a few years ago, where latency is everything. We got a huge $15k plasma display (at the time), only to discover it had something like 90 ms of latency! Since we were already pushing our latency budget by sending signals across the country and loosing frames here and there through video processing equipment and codecs, that 90 ms was more than enough to push us over the edge and make the system very difficult to use for natural conversation, and throw the audio/vidio sync visibly out of whack. The plasma had to be replaced. Three frames may not seem like a lot, but it is quite noticable.
I've delt with a lot of high-priced high-quality plasma systems over the years, and the lesson is definitely "Buyer Beware". The high quality 56" plasma systems can be stunning, but remember that you're also investing thousands in a device with a fairly limited lifetime, and no real industry-wide quality standards and more marketing buzzwords and cheap tricks than you can shake a stick at.
If you using plasmas as a computer display you will see even more artifacts. I've seen widescreen plasmas that could not accept any resolution modes of a correct aspect ratio. Many displays use a great deal of image processing to apply tricks to make the display look good, but sometimes the processing can seriously disturb things like computer text. I've seen apparent color segmentation problems on a lot of displays, and just a lot of artifacts in general.
-braddock
This is interesting. I have my wife setup with a SuSE notebook (+crossover office). She used it for a recent convention presentation connected to a generic video projector. She found a nice feature on the projector that would scale some MPEG videos up to full screen & it was easier than her figuring out mplayer, so she used it.
She came back from the conference & complained that there was a clear sync issue with the audio. I tried mplayer on her notebook & videos, but *could not* reproduce the defect.
Now I wonder if this type of hardware was to blame.
What is the deal here? This is like a car maker shipping vehicles all over the country with brakes that don't work.
This is an easily spotted problem and a simple fix.
Sometimes I worry about all these "product engineers" working with what amounts to computer technology more and more. They often don't seem to understand what they are doing or how to work with the technology and end up doing a really bad job.
Think someone who did a whiz-bang job on a satellite receiver in the early 90s being put on a project to create the company's new DVR. Then you get all kinds of wonderful glitches, slow and erratic menus, missing features that should have been obvious, plus features that are useless.
Too often you feel like the person who designed this thing is better off behind a soldering iron than a line of code.
The bottom line: If your product has a microchip in it, you need software engineers that can write good code and hardware engineers that properly understand how to put together computer systems using available standards.
Natural != (nontoxic || beneficial)
>Did I mention I don't own a TV? Well, let me tell you all about the superiority of my ways and the inferiority of everyone else. Here goes....
We're waiting...
Here's an example chip. The MAD 4868A is designed to address the video delay in some of the mainstream flat panel televisions. I'm sure there are other chips for this. I just happened to come across this one with a quick search.
MAD4868A press release
Whips out credit card......
I can't say if they're effected or not, but there is a good chance that they're affected.
For de-interlacing you need to get the second field before you can figure out what to display. So there is 1/30 second there (assumming you wait until the end of the second field before displaying the result of the first one, if you really can sync it up carefully you could get the delay down to 1/60 second).
It does seem compensation is the only solution. But there is a problem: lots of high-end equipment produces the sound and sends it to the speaker without any intervention from the tv (ie the speakers are plugged into the stereo amp, which is plugged into the dvd player, not the tv). So it's more like the compensation has to be there.
I would think you need to compensate for the speed of sound as well if you are far enough away from the tv screen. Right now though these problems may cancel out some...
It's a rip on sync errors as seen by a slashdot first-poster.
CAPTAIN OBVIOUS! Yes, we know that this problem doesn't just affect lips. Or that there is some special circuitry which performs lip compensation only at the receiver.
;)
PS: What are these 'pelvic trusts', anyhow?
Just sit back from the screen about 70 feet and the sound and lips will sync up just fine!
-- If god wanted me to have a sig, he'd have given me a sense of humor.
However, doesn't the same degree of delay obtain depending on whether you sit at the front or the back of a movie theater?
Seeing bad movies only encourages them. Watch responsibly
I used to develop code for digital set-top boxes, and I can tell you that this is not a trivial problem.
Because of the way MPEG-2 video works, there is an inherent delay in decoding (frame order in the bitstream isn't necesarily the display order because of the way P-frames and B-frames work.
Audio is slaved to the video through the use of timestamps, but the audio and video frame boundaries don't line up.
I'm not sure if the problem is really lip-sync delay, but building in enough buffering to account for video delay while not glitching audio.
Most people don't notice minor video problems, like repeating or dropping a frame, but they will hear lots of little audio glitches. Also, when a hardware audio decoder runs dry, you usually get a really bad artifact (it sound like stepping on a squealing mouse), and it takes 2 to 4 frames of audio to resync.
(S(SKK)(SKK))(S(SKK)(SKK))
with my ReplayTV unit a lot ... drives me nuts when the dialogue lags. Usually, it's hardly noticeable, but once, it got about 5 seconds behind. That's a lot when it comes to video, as the camera moves to the next character, you're hearing the voice of the last character shown.
I'm not sure what the secret to success is, but the secret to failure lies in trying to please everyone -Bill Cosby
I've seen this problem. I noticed it during the Britney Spears pay-per-view concert. Sometimes it seemed like her lips weren't even moving at all, but she was still singing.
It's good to use your head, but not as a battering ram.
the cheaper solution is to sit further away from the screen, 60ms * 300m/s is only 18 meters.
Just crank up the volume and buy some binoculairs
If you buy model X and it sucks, that won't stop me from purchasing X because nobody researches this stuff beforehand. I just go to the guy in the TV department and he points me to model X and I buy it.
The market does nothing to punish poor quality.Free Mac Mini Yeah, it's
...the era of video scalers, deinterlacing, and 2:3 pull-down...
First, its 3/2 pull down. Second, it's been around since the beginning of film-to-tape transfer.
Morons.
Both original article and slashdot posting are quite inaccurate..
The delay is not caused by cheap processors, that is a myth. Just think about it, even delaying the video by 1 second will not reduce the required processing power...
In fact the delay is a technical neccessity for some of the algorithms employed in modern television. For example motion interpolation for 100Hz TV requires the knowledge of at least one frame in advance.
Also the "delay" in TFTs, as mentioned, has nothing in common with the delay due to video preprocessing....
The only remedy for this problem is to have an option to turn all the preprocessing off for video games and have an artificial audio delay, so it matches the video. Nothing that is out of bounds for an average TV...
If you have a Samsung DLP and you are experiencing this problem, adding a fixed amount of delay does NOT guarantee a fix. The reason is that in Samsung DLP sets, the delay is intermittent. Often times it's barely noticeable (60 ms or less), but sometimes it spikes to as much as half a second. I used to have the Samsung HLN567W but I returned it before my 30 days guarantee was up. Picture Quality was great but the intermittent audio/video sync issue was driving me nuts. I first read about this problem (on Samsung DLPs) last August, I bought my TV last January, and apparently the problem still exists in new sets being sold currently. That makes this problem at least 9 months old... looks like the resolution is not easy otherwise Samsung could have fixed this a long time ago. With all the high tech circuitry being added to consumer electronics nowadays, regular consumers are now becoming beta testers for these consumer products too. Welcome aboard!
just use REALLY long speaker wire to compensate!
s/War on (some) drugs/strategic action plan against certain narcotics of mass destruction/
THIS THING CAN TURN ON A DIME, MACROSSZERO STYLE ALSO FUCK BETA, ~NYORON
Shithead.
When the MICROPHONE in the bass drum kit moves, it has the same stroke issues. So in the mix, the signal levels are as measured. On replay you're just mimicing the mic movement, which is subject to the same physical laws.
It really has no effect. Besides, the guy mixed on some monitors. So use monitors with the same phase/freq plot if you're so damn concerned.
THIS THING CAN TURN ON A DIME, MACROSSZERO STYLE ALSO FUCK BETA, ~NYORON
Could you look up whether their effected? Thanks alot.
When my DVD player gets the audio out of sync with the video I can correct the problem by stopping the video (not pausing) and then restarting it. This only seems to apply tangently to the article at hand, but I bring it up to show that latency problems can show up because of any device in the chain, not just the display.
This space for rent. Cheap!
DirecTV typically has a 2 second lag behind network broadcast. So if you watch a game on a local channel, or the news, the cable in the PiP will lead the DirecTV feed. Sometimes we'll have two TVs on in close proximity, one on Cable, the other on the Sat, and when you hear them going at the same time it sounds like being in a really, really big cave or stadium.
THIS THING CAN TURN ON A DIME, MACROSSZERO STYLE ALSO FUCK BETA, ~NYORON
Thus today's syncing technology consists of:
The SMPTE LTC code is both recorded on an audio stripe (channel) of a multitrack audio recorder, and on an audio stripe of the film-camera. It is also possible to sync MIDI and DV-timecode to SMPTE time-code.
Now, there is equipment that creates all these signals, or you can build a chain of syncs. Blackburst is often the master, on which the word clock and SMPTE time-code is synced with a PPL (phase locked loop).
I just started in the video and film business and I was stunned by all of this.
my speakers do this automatically - notice the tweeter on top is spaced further back, adding a slight delay. The midrange is back a bit from the bass, too.
HIV Crosses Species Barrier... into Muppets
Sit farther away.
Since light travels faster than sound, you just need to calculate the distance at which the headstart the audio has is overcome by the difference between the speed of light and the speed of sound.
The sole problem is the bottom line.
MPEG, what is used in the USA to encode HDTV signals, had this solved over a decade ago. So it's not the encoding.
MPEG-2 decoder cards have been keeping lip sync for years on underpowered computers. So it's not a hardware problem.
MPEG-2 decoder software has been keeping lip sync for years when video can't keep up with the sound. So it's not a software problem.
LCD Response Time isn't the culprit, because at 30 frames per second, response times are well under the 33 ms needed. According to the article, "A good response time starts at around 25-30 ms." (Even with 60 fields per second for progressive video, a pixel is only touched once every two fields, so the necessary response time is the same.) So it's not a display problem.
What it boils down to is the manufacturers are unwilling to pay a few more pennies for a simple buffering scheme to do it right. They tried to boost their profits by that tenth of a percent (if that) by offering a substandard product in the hopes that no one would notice or blame it on the manufacturer. It's pure greed.
There is a more sinister side to this - monitors that can't keep up, get into BIG problems when dealing with another venue that is pushing towards them more and more: VIDEO GAMES.
I'm actually serious. While the normal populace may scoff and deride those who play games like Soul Calibur or Street Fighter until they can actually count how many frames a particular move takes to execute - and how many frames from when the button is pushed to when the move reaches its damage point - everyone likes nice, crisp controls.
They want to know that when they push that button, it went into the system immediately.
Now you're talking about adding a possible 4-5 frame delay to the entire system - but you CAN'T make the video game system have the same delay, it'd have to recalculate everything backwards in time to compensate.
So what do you do there, huh? It's a pretty crappy workaround solution.
The problem is most noticable when you have a PC which is assumed to have roughly instantaneous video/audio output (I mean vsync/sound card dma was once used for timing for gods sake). HDTV systems compensate internally on top of all the other processing they have to do.
Monitors on DVI have no provision to send digital audio down that DVI cable. Usually there's a USB audio connector or RCA jack... or otherwise the audio is routed to a stereo amp or what have you that's external. So we cannot assume that a display with built in audio will have digital input... Unless it has SPDIF. In which case yes, it needs to go ADC, delayed, then DAC. Not a big deal... I'd rather do it at the source in an audio driver on the PC itself. Same thing with a console.
THIS THING CAN TURN ON A DIME, MACROSSZERO STYLE ALSO FUCK BETA, ~NYORON
My LCD monitor also has composite/s-video in, and doubles as a TV when I'm at my desk. Since I don't have a dedicated tuner yet, I'm using the output of a TV to drive it.
In addition to the lip sync delay, I've also noticed that anything with sudden movement is blurry. Credits (which are barely readable as it is) can't be read, the ads in the background of a hockey game often are blurry (the IBM logo appears as just black & blue horizontal lines, as an example). To read anything, I need to go back to the CRT.
I use Macs to up my productivity, so up yours Microsoft!
Why? Most often it's better to get discreat components that do one thing very well thus seperate audio and video(film) gear and you need to get and keep things in sync. Before there were cheap digital TBC's you had to use cable to adjust for delay.
No sir I dont like it.
This is another reason why the digital revolution sucks. Digital processing does wonders for mathematical manipulations and systems modeling but it definitely is inferior technology for real world entertainment.
If we could've spent half the money on vacuum tubes and improving analog quality as we've spent on silicon transistors and digital conversion we'd have HD analog TVs with no sync problems at all unless the broadcaster didn't wind the reels correctly.
Reality is analog. Brain chemistry is more about transition states and steady states than it is about finite pulses.
+++ATHZ 99:5:80
I recomend burning.
I personally couldn't stand it if my neighbor (with a standard CRT television) found out who the big winner of American Idol was 60 milliseconds before I did!
Slow processors can significantly delay the generation of the output video. Not only that, but the amount of work the processor has to do, which depends on how many changes from frame to frame take place, will cause varying delays.
The way the problem usually manifests itself is that the delta between video and audio gets biggere and bigger, the two slowly drift apart. The video is, of course, being backed up in memory. At some point it will run out of buffer capacity. The olde way of dealing with this was to just flush the buffer, which brings thing back into sync (for a while), but usually causes a nasty glitch in the video (blank screen for a few frames) in most cases.
Newer techniques involve dropping frames, more of them as the buffer fills up.
A good indicator that you are getting buffer overflow is when you change channel, then change back again and all is back in sync (for a while). This will have flushed the video stream buffer, and life will be good, untill it backs up again.
Faster processors can deal with the overall data rate without having to resort to these extremes, but the inherent delay caused by having to buffer a frame (or more) to be able to decode the next (because we are dealing with frame deltas in MPEG) will still cause varying delays in the video.
The real answer is to use adquate processing power, and to modify MPEG to insert timing marks into the video and audio streams, and allow the system to automatically and incrementally adjust the audio delay to keep it in sync with the video.
Expect to see a squadron of flying pigs before this happens ...
An even better answer, of course, is to scrap this digital TV crap. The best digital TV signal doesn't hold a candle to the best analog TV signal. All that digital buys is the ability to squeeze another 150 shopping channels onto every satellite at the expense of video quality - but that doesn't matter, its marginally better than VHS, so what will the consumers ever know?
Can you imagine how GranTurismo would be in a move-in-turns scheme?
Could someone tell me the flaw in my logic?
So, if the video processing is slower than the audio processing, shouldn't the audio steadily get further and further behind the video.
Is it just the initial frame that is slower? If it's a constant 3 frame difference then the velocities are the same for the audio and the video, right? Is there frame skipping to make up for this?
--Steve
...it's a feature!
Seriously, slapping in audio delay is not a Bhig Dheal: I have to throw in an 8 second delay for $dayjob, and the silicon count is derisory.
More to the point, having a constant video delay is really useful if you want to do trick audio processing like room or speaker EQ using finite impulse response filters (FIRs), which tend to have long delays of their own in these applications.
Francois.
After various setups I now have a nforce2-motherboard with SoundStorm onboard(A7N8X-E Deluxe) to do on the fly AC3-encoding so I only have one cable running from my HTPC to my stereo(and yet be able to switch between mp3/divx/tv/dvd etc.)... Only thing is, when I watch live television, this conversion (stereo-2ch-analog -> AC3 -> analog) comes with a little latency... I've been thinking if how I could get some latency in the videosignal, but it seems there's an answer now :-)
(and when you wonder why I don't just skip the AC3-part, it saves me a pre-amplifier as now I'm able to plug in my AC3-decoder straight into my amps...)
There is no logical reason to expect these two processing paths to introduce the same delay. In the past, both paths were fast enough that the difference was small enough to not worry about. Now it looks like video is slow enough that it matters. However, it's not wise to assume that video will always be the slow one--maybe the next audio format will be very slow.
Hence, it seems the the right then to do is make it so audio and video both have adjustable delays, so that they can be matched as needed.
Where to put these delays? One possibility that comes to mind is in the DVD players, PVRs, VCRs, and TV tuners. E.g., everything that provides an A/V signal into the system could provide a means of adjusting the delay.
Another possibility is to have display devices provide a video delay, and A/V receivers to provide an audio delay. Since most systems only have one receiver and one display, that would be cheaper than having every source device provide both delays, and easier on the user.
It would also be very nice if the manufactures would get together and provide a way to automatically set these delays, by having the display and the receiver talk to each other and figure out which of the audio and video is slower, so the other can set its delay.
In Spain, most soccer matches are pay-per-view. Being dutch, living in Barcelona, I have dutch satelite television, so I could watch the FC Barcelona soccer matches, but if I had non-dutch friends over, I would put the radio for catalan commentaries, but the image would be several seconds up to half a minute behind. Very annoying to hear the radio-host scream GOAL! and see it happen 5 seconds later. Now, as a coincidence, I wrote tapiir, a linux multitap delay application, that can deal with long delay times. Routed the radio through my soundcard, adjusted the delay time, problem solved :-) The other way around (sound lacking behind) would have been more difficult.
>I don't understand why they couldn't have anticipated this problem before they shipped the TVs, though. Isn't that what QA is for?
Dilbert: We have a serious flaw in our product that can be corrected with a cheap, quick swap-out of the Model 9 Frammish Board with the Model 9A. You want me to recall all 495,000 units that have shipped to our value-added resellers and make the change, right? Remember, I told you about this six months before any of these units shipped.Pointy-Haired Boss: Noooo. Let's wait and see how many retail customers call and complain. We'll send some minimum wage guy out to swap out the card for the one's that somehow manage to call us.
Some mornings it's hardly worth chewing through the restraints to get out of bed.
I've only seen it happen once, but on my older Sony 3rd generation DVD player (which is now my parent's DVD player), the audio was out of sync with the video for one movie rental, "Meet the Parents." The video outputted to S-Video on the television (because the model was the year before JVC started equipping 27" televisions with Component jacks) and had RCA audio output to the television with the Hyper Surround activated. Terrible. Yet its the only DVD that I've witnessed it happen to. Even the $3.99 Vicent Price "The Last Man on Earth" from Best Buy didn't do this... :0
"Right now, somewhere in this world, Scott Baio is plowing a woman he doesn't love," - Peter Griffin, *Family Guy*
Finally, with the latest state of the art digital TV with innovative lip-sync technology, when you turn it on, you would see padding frames (due to lip-sync activation) that would appear as if the image oozes out from the center. And when you turn off the TV and deactive lip-sync, the image would ooze in to a circle and fade.
I love nostalgia.
I once had a signature.
If AMD can sell 2ghz chips for $100....
I use a program called dscaler (sourceforge) to upscale my laserdisk player for CRT projection, so far it hasn't been that noticable, and I'm using an 800mhz Athlon.
I find it hard to believe that it would be that difficult to incorporate a faster/better engineered processor or DSP to handle the video scaling functions, especially in plasma displays that start at $3000 and higher.
Does the DVDo units (the outboard device that pretty much killed the line-doubler market) suffer this delay? That unit was at the forefront of cheap line doubling, if it can upconvert without causing too much of a delay in audio there is _NO EXCUSE_ why the embedded chipsets in modern sets aren't able to cope.
Southeastern Virginia REPRESENT!
When I sat way back from the screen. I moved my barker louge to within two feet of the TV- now it is gone.
From their site:
Nice speakers, crappy camera.
Synergy is your friend
Maybe they shouldn't use a Britney Spears video to test their screens.
Most modern receivers allow to set speaker delay, so this problem can easily be fixed by increasing the delay by 60ms. TV and movies should be ok; it won't fix gaming and videocon sync problems though.
"You mortals are so obtuse." -Q
that Brittneys videos will now play normally?
Does DLP also have the same/similar delay issue as plasma and LCD? I know the lip syncing can be very annoying. I have a home theater using ATI stuff and their time delay features for the TV program display a similar lip sync problem. Usually in the reverse though, frames are well ahead of the sound. It basically makes the time shifting of the program useless. It's very difficult to watch TV when the two aren't in sync. I'm wondering if other TV software also have this problem? Does TIVO and other devices like that have the problem?
I'd hate to spend money on a digital tv only to have everything look like a B kung-fu movie.
Milli Vallini can now blame it on the hardware.
Table-ized A.I.
I tried to play racing games on a tv-card through my computer before, and the delay made it impossible to play.
Any delay will cause problems for twitch-style games, but if it is more than 1/10th of a second it gets too hard (I was playing Gran Turismo 2 at the time).
Is the display delay still present with progressive scan component signals on HD tvs? Those shouldn't have to deal with any image processing, right?
The newer (and less expensive even) Apex units don't seem to have this problem. And they will happily play a cd with a bunch of mpegs on it. Cool.
347 m/s speed of sound in air
*
60 ms of time
=20.82 meters
At least Milli Vanilli did it right. Their lips moved.
It's cool that there's finally some article on this. Some guy at work posted a message on an internal message board about this phenomena and I even posted an inquiry on avsforum.com and don't remember getting any responses. Basically, he said went to a gethering of Halo players on Xbox. Some guys brought direct view CRT TVs and some brought Infocus X1 projectors (I have 1 myself). The guys w/the projectors wanted to use the direct view TVs and they told him he could use the projectors. The reason was that apparently people w/the regular TVs were kicking the butts of the projector guys due to the delay on the projector. I don't recall if any people swapped roles/display devices to see if the really did throw them off. I look forward to the day when somebody has done some real world measurements of this on shipping products.
But the again, the video specs don't leave much to be desired.
I've just got a digibox that picks up digital radio stations in the UK. However, the digital radio stations are about two seconds delayed from the analogue stations.
Not a problem, you may think, since it doesn't have to sync with anything. Except that on the hour, Radio 4 goes pip pip pip pip pip piiiiiip to tell you the exact time. But on digital, its two seconds slow.....
Like the subject says, it's not just video decode - you also have to take account of the time required for composition of multiple layers, manipulation, resizing etc. It adds up, and usually video is the dominant path through a system (in that all the other outputs add buffering to compensate for the latency).
:-) Being in the lab when it's being tested is no fun at all though.
And yes, an audio decoder underflowing sounds bad. That's why we go to great lengths to avoid it happening.
Having said that, I don't know if this is what the TVs are doing. It sounds like they're building in compensation to the sets, which doesn't sound like a great idea for things like playing games.
There is a simple solution to this problem: Simply delay the audio by 60ms as well.