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Posted by blackburst@aol.com on 12/05/06 14:34
Scott Dorsey wrote:
> This is the normal state of affairs in the 21st century. The usual thing
> people say is that "nobody else ever complained."
>
> Soon everyone will be watching 1:1.33 images stretched out to fit their
> widescreen TV, with synch drifting four or five frames off in either
> direction. Welcome to hell.
> --scott
Video/Audio synch has long been a problem. In the beginning, analog
"live shots" were sent back to the studio via microwave, where the
video and audio then took different "paths". The video went through a
frame synchronizer: Early units imparted 2-4 frames of delay, but that
was eventually reduced to under a frame. Then came satellite for ENG,
and again, there was an even larger delay problem (10+ frames),
although it affected the audio to the same degree as the video.
Along came digital, and now we had the problem of too-slow A-D and D-A
converters: The audio units were fast and transparent in the time
domain, but the video conversion was "much" slower. Now we have HD
(hi-def), which currently has MUCH more information to convert, so V/A
delay is again a big issue. Faster processors will help, but the
separate paths for audio and video will continue to cause problems.
I am working with a manufacturer on a solution: A time reference signal
encoded into both the video and audio at the source, and a
reader/resolver at a certain point in the receiving end. But it only
works in the digital domain. And we have another company who just
introduced a competing design. Yes, it's hell, but we're trying to make
it freeze over!
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