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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!
"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.
booo I say
I only watch 1960's Italian westerns...
Italian westerns? Ohh, you mean easterns...
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?
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.
Comment removed based on user account deletion
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.
...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.
Italian westerns? Ohh, you mean easterns...
No, Spaghetti Westerns. Typically made from the mid 60s and early 70s, they made Clint Eastwood into the star he is today. Fast cuts, trippy music, lots of gunplay, and they were heavily (and poorly) dubbed, as most supporting roles were cast with italian actors.
They are considered classics now, as are the likes of "Fistful of Dollars" and "The Good, the Bad, and the Ugly" Wonderfully loony and fun to watch.
...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!
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 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
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))
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...
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.