[opendtv] Re: Digital vs. Analog Quality

  • From: Craig Birkmaier <craig@xxxxxxxxx>
  • To: opendtv@xxxxxxxxxxxxx
  • Date: Mon, 14 Jul 2008 09:06:11 -0400

At 5:19 PM -0400 7/11/08, Manfredi, Albert E wrote:
This is your standard reply when you are unable to follow a thread. A
common problem among those who prefer to transmit than to receive, which
was oh so painfully obvious in this thread too.

If you go back to the references Cliff posted on 7 July, you will see
what his point is.

The references state that the color resolution of NTSC composite
interfaces is limited to about 120 lines in practice, and 140
theoretical. HOWEVER, the color broadcast in OTA NTSC transmissions is
much less than that. Here's the quote:

"NTSC Broadcasts (composite) - 120 lines best, 40 - 48 lines typical for
reddish orange and greenish blue; 40 - 48 lines for most other color

So, what was this all about? It was about explaining that if you use a
CECB to decode a TV signal, as opposed to watching the NTSC broadcast,
over the composite interface, you should notice much better color
resolution than from the NTSC broadcast. Because the CECB creates the
composite signal from the 4:2:0 digital, and is not limited to the ~40
lines in practical NTSC broadcasting. It is ONLY limited to the 120
lines of NTSC at its practical best.


I already understood what we were talking about . Clearly you still do not understand what you are talking about.

You are correct that a CECB "could" produce far better quality color than an NTSC broadcast as the component source has much more color information available prior to MPEG-2 encoding. In reality there may or may not be as much accurate color information available after decoding.

But that information will then be band pass limited when it is NTSC ENCODED for the composite video output. The net result may be better, or it may be worse than an NSTC broadcast depending on the quality of the MPEG-2 compression.

That being said, this has NOTHING to do with Cliff's claim that Betacam offered a baseband composite video output with more color information than any other NTSC encoded source.

The issue is the NTSC encode bandpass...

By the way I do not Capisc...

But I do capiche.


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