Archived from groups: alt.tv.tech.hdtv (
More info?)
Jeff Rigby wrote:
>
> The problem is not with your Samsung but with HD. When you hook the output
> of a set top box directly to your stereo and the component out from the set
> top box (video direct to the TV), the sound from the stereo is going to be
> at least 1/30 of a second off (ahead, the time it takes to process a frame
> of video).
>
> All HD TV's have a frame buffer/converter to process the incoming video to
> the display resolution of the TV. This conversion can't take less than
> about 1/30 of a second. There is a sound delay setting to correct this built
> into the TV. But you have bypassed that by going direct from the Set top
> box to your stereo. (I don't know of any other way to do this when using
> dolby digital.) Most people can't see this 1/30 sec difference in pic/sound
> but you can hear it if you have the TV speakers on at the same time as the
> stereo speakers.
>
> There are also differences in timing from Dolby digital audio to TV audio
> that are the fault of the TV station. You can hear that by goinng from
> station to station and hearing a difference in the sound delay.
Yes. If it were just 33 milliseconds, it wouldn't bother anyone. That
is, assuming they didn't try to run two unsynchronized audio systems at
once - that's always going to be audible. (And it's a bad idea even if
the feeds were in perfect sync.)
But the problem is that these delays aren't just in the set. They can
be in the original broadcast, and they can be introduced by other
components (the cable box, for example).
And keep in mind that the 33 msecs is just the minimum. The Samsung
DLPs are spec'd not to exceed 65msecs of video delay. Most of the time,
they are well within that spec, but even if they pushed right up to that
limit few viewers would notice it.
Unfortunately, the Samsungs (the HLNs anyway) sometimes go well over
that spec, depending on exactly what's in the video stream being
processed. In some cases, the Faroudja chip used in these sets can take
even longer to process each frame. That's why Samsung has been
replacing these boards for customers who call and complain about this
problem. The newer components bring the set into spec. But it still
won't solve problems that occur before the signal gets to the TV.
Even with a audio sync setting in the receiver, it won't be possible to
get it to be always perfectly in sync - unless you want to retweak it
for every show and/or channel. The best you could do would be to pick
an average setting that was "close enough". And that's probably not a
bad solution.
/www.integrahometheater.com/model.cfm?m=DTR-9.1U2&class=Receiver&p=i
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