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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."
Back ~1990 I bought a device from Barkus Berry Electronics which delayed higher frequencies a few ms to let the "slower" bass and low-mid frequencies play catch-up. The idea was that the woofer and midrange had a longer stroke than the tweeter which was required to make the sound. This let the bass and mid leave the speaker at the same time as the high end stuff.
I still have that unit, it really seems to "open up" the music more.
Trolling is a art,
...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.
We frequently watch hockey with the radio on going. The video comes in a second or so behind. This makes the radio play by play seem psychic at times.
"He shoots he scores!"
Then we see the shot and the goal.
t
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
first you introduce audio delay with buffering technology and then you intruduce user input delay using psychotropic technology.
Seriously, the post makes reference to the use of cheap proccessors hence the video delay. By 2006 the expensive processors of today will be cheaper, and eventually cheap enough.
"The quality of life is inversely proportional to the number of keys on your keyring."
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
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!
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.
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.