[opendtv] Re: Digital vs. Analog Quality

  • From: John Willkie <johnwillkie@xxxxxxxxxxxxx>
  • To: opendtv@xxxxxxxxxxxxx, opendtv@xxxxxxxxxxxxx
  • Date: Mon, 7 Jul 2008 13:28:28 -0700 (GMT-07:00)

Dan;

I noticed significant differences in video quality between studio shots and playback of news segments when I visited LV in April.  I was watching on an analog TV set.  This issue seemed across several stations.  I suspected early-generation digital playout devices, or -- shudder -- analog tape.

John Willkie


-----Original Message-----
From: dan.grimes@xxxxxxxx
Sent: Jul 7, 2008 8:37 AM
To: opendtv@xxxxxxxxxxxxx
Subject: [opendtv] Re: Digital vs. Analog Quality

I see I need to be a little more specific in my observations. 
 
Just so everyone is clear, I am not trying to compare the overall DTV system's picture quality to NTSC.  Just comparing the two mediums to those of us that still use old SD CRT TVs.  And I am not ignorant to the qualities of HDTV, digital or MVPDs.  I have them at work.  I am only trying to relate my experiences as an average FOTA consumer.  I do not know the resolution of my TV but it is rather low, naturally, compared to our studio grade monitors. 
 
Also, I am using an outdoor antenna with a strong signal.  It give excellant NTSC reception.
 
For the most part, the NTSC picture looks much the same as the baseband composite signal coming from the DTV converter box (no S-video input on my TV).  Both have their strengths.  And I am comparing overall look, not just resolution.  In fact, the resolution on the DTV converter box might be a little better, but also harsher.  The NTSC actually looks better. 
 
Perhaps the NTSC resolution matches the SD CRT better and thus gives a more pleasing picture.  This is noted in graphics.  Lettering from graphics looks clearer on the DTV converter box output compared to the NTSC signal.  So perhaps the DTV has better resolution, but a harsher picture.
 
The RF output signal from the converter box does not look as good as the composite output, but still very nice.
 
Live broadcasts, specifically the studio cameras, look better on NTSC.  There are little, if any, compression artifacts which are appearant on the pre-recorded material.
 
But I can't imagine the compression art ifacts going away just because they are on an HDTV.  If I can see them on my SD CRT, I would think that they will be seen on and HD TV.
 
But there are artifacts that are showing up on the CRT that I doubt are on an ATSC HDTV. 
 
Case in point, I watched the IRL race on ABC this Sunday.  The NTSC looked better than the downconverted video coming from the DTV converter box.  The horizontal lines with slight slopes had terrible jagged edges.  And the fine horizontal lines in motion created an awful shimmer.  The vertical resolution seemed much less because of it.  I am guessing that this is a deinterlacing problem of a 1080i signal.  The NTSC looked better and I am guessing that the signal was converted to 480i either at the TV station or the network headend.  I am guessing it was done at the TV station, using only one HD feed and converting it to SD for the NTSC broadcast.  Pe rhaps it handled the conversion better.  However, it, too, was showing signs of the problem but because of the lower resolution, was not as apparent.
 
Please know that I am not trying to make the NTSC better than ATSC.  I am not arguing that the overall system is not an improvement.
 
So that is my observations as an average FOTA customer using one of the new DTV converter boxes.
 
Dan
 


 

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