[kwlug-disc] Fwd: Re: HDTV

[John Johnson]

Well said, Jason.
With marginal signals you also see freeze-frame and pixelation where 
part of all of a frame cannot be reconstructed.

I like the days of "snow" - both visual and the hiss.
Because, at least, one could watch the broadcast if it was interesting.

To lighten up the discourse I would like to offer this (unconfirmed) 
story of TV and Olympic Hockey from the 1980s or 1990s.
(Lillehammer Norway was in 1994.)

To have live TV of events like hockey there was a need for on the fly 
conversion of TV signals from the European PAL signal format to the 
North American NTSC signal format. And And this was in the early days of 
compression where the signal content was reduced for transmission over 
the satellite channels to reduce "air-time" costs. The signal was 
reconstructed for re-broadcast on North American networks.

This was all well and good and worked well for most events. But hockey 
presented a problem.
A small black dot moving over a large white surface kept disappearing on 
the rebroadcast.

The puck was treated as noise and was removed for the re-broadcast.

John Johnson

On 2014-02-26 11:34, Jason Locklin wrote:
> Digital is all or nothing. If you have a marginal signal, though, you
> will get what is essentially packet loss in a MPEG2 stream, so you get
> artifacts like horizontal bars of missing pixels (all one colour), and
> audio dropouts or squawks. Unlike analogue, you really can't just watch
> a poor signal as it's incredibly jarring, but as long as there is a
> decent signal, it should look perfect.
> -Jason
>