[opendtv] Re: Digital vs. Analog Quality

  • From: Craig Birkmaier <craig@xxxxxxxxx>
  • To: opendtv@xxxxxxxxxxxxx
  • Date: Tue, 15 Jul 2008 00:24:16 -0400

At 5:04 PM -0400 7/14/08, Manfredi, Albert E wrote:
lso, when NTSC is transmitted over the air or cable, isn't the reason
for the rapid dropoff of chrominance that you have to avoid interference
with the audio carrier? If the color carrier is at ~3.58 MHz, then 0.5
MHz above that gets you to almost 4.1 MHz. At 4.2, the luminance drops
off to make way for audio at 4.5 MHz.

If you're transmitting this over the composite baseband interface, isn't
there much less need to low-pass filter this chrominance as quickly?
Seems to me a more gradual drop won't hurt anything.

Problem is that composite baseband uses the same subcarrier scheme as NTSC. It might be possible to have more chroma bandwidth, but I'm not sure that anyone does this in the real world.

All of this is academic, as the production world has largely moved beyond baseband NTSC production.

And remember, this thread started out talking about what you can get out of a CEBC for display on a consumer grade NTSC TV.

Regards
Craig


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