Dwayne Reid wrote:
> At 05:25 PM 1/10/2006, Jose Da Silva wrote:
> 
> 
>>Now imagine you are watching the news and they show an on-the-spot
>>segment recorded from a handy-cam type camera.  I would think that you
>>are getting colourburst according to the portable camera and not
>>according to studio-quality colourburst.
>>I think the colourburst would be accurate for studio stuff (generated on
>>sight) or even film type shows and movies, but now you get a lot of
>>media recorded digitally, VCR tapes, etc, and pumped out via plain
>>VCRs, DVD machines, etc, ...all of which produce their own colourburst.
>>We may possibly be seeing the sunset on colourburst as an accurate
>>reference sent out by the TV services.
> 
> 
> I think that you will find that all such external sources are fed 
> into a Time Base Corrector.  This synchronizes the external source to 
> the station master clock.

Not any more. Most switcher are now 'all digital' which means
they effectively have a frame synchronizer on every input.
This is why you now commonly see 'lip sync' problems.
The video got retimed a few too many times without a
corresponding delay being added to the audio stream.

As we move to fully digital delivery of video streams,
this lip sync problem should go away.

> Harold H may be able to shed some insight on this.  I'll also ask a 
> couple of my TV Broadcast tech buddies about this later this week as well.

Would be interesting to see the diversity of solutions out there from
old analog plant to modern completely digital ones.

Robert
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