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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."
Actually, that's the only way to fix this is a work around. As not only the article states, but common sense states that to fix this, you have to make video processing faster. We cannot do this with our current technology. So we have to use a work around until the technology catches up.
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'll probably find that the "delay" on most receivers actually refers to the delay in putting audio through the rear channel, thus creating more of a "surround" effect if you have to sit in line with the rears.
See, to get a sweet spot in a home theatre set up (wish I had room for a sweet spot in mine) is to set the rears equidistant from your ears as the fronts are. Unfortunately, many room environments don't allow for this, so you can use the receiver to "delay" the rear signals by so many milliseconds to make the surround more convincing at close range.
Karnal
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.
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