mm wrote:
But thoss were in the analog signals. When they went to digital, why
didn't they stop using PAL or stop using NTSC? That is my point.

Because they could. :-)

Seriuosly the digital standards were developed with keeping the old systems
in play, even if they were no longer needed.

What tied them to both PAL and ntsc at the same time?

Regional pride?

Or was it because they wanted current analog tvs to be able to receive
digital signals that went through a set-top digital to analog
converter, and some tvs wanted 50 cycle and others 60 cycle, so if the
air-borne signal was the same, it couldnt' be converted to one of 50
or 60?


It really did not matter. Maybe in 1983 when digtially encrypted HBO satellite
receviers were designed, but in 2005 when the US conversion started, it was
simple enough to use anything they wanted and produce NTSC or PAL or computer
RGB output or all three on a set top box.

The actual encoding is not PAL or NTSC anyway. H.264 which is the current
standard for high end compression does not have a fixed frame rate. I mentioned
that in a previous posting.

With a fast enough decoder chip you can take any resoltuion and frame rate
and put out anything else. My Western Digitial TV Live unit will take
almost any compressed video file up to 1080P60 (1080x720 60 frames a second)
and put it out on the fly, with audio in sync from 480i60 (standard NTSC),
or 560i50 (standard PAL), in composite, 480P60 or 560P60 in component,
or digital in HDMI with several choices in between.

Why you could not slap an ATSC or DVB-T or the Japanese standard tuner
chip (or all three) on it instead of a USB port or ethernet is more of a
matter of product placement than anything else.

Geoff.
--
Geoffrey S. Mendelson N3OWJ/4X1GM
Those who cannot remember the past are condemned to misquote it.