[opendtv] Re: Some results - 1080p @ 60 is Next?

  • From: Mark Schubin <tvmark@xxxxxxxxxxxxx>
  • To: opendtv@xxxxxxxxxxxxx
  • Date: Fri, 04 May 2007 16:47:59 -0400

You're both right. Yes, 720p always scored better than 1080i, but at uncompressed rates, the ranges of responses overlap considerably between the two. Starting at 18 Mbps on the plasma and 13 Mbps on the LCD, there is no overlap, i.e., no question at all that 720p scored better for all observers.


TTFN,
Mark


John Shutt wrote:
Bert,

I got the opposite impression based both on the graphs presented yesterday, and the bullet points that follows your quote that said:

------------------
* The 720p/50 format showed better image quality than the 1080i/25 format for all sequences and
for all bitrates;

* With decreasing bitrate in the compressed domain, the difference between the 720p/50 and
1080i/25 format became more marked;
-----------------

I've been wrong at least twice today, but I will go out on a limb and presume that "all bitrates" includes the uncompressed bitrate. The differences may have been small in the uncompressed domain, but the graph clearly shows 720p above 1080i. The gap widens as the bitrate lowers, but 1080i is never found superior to 720p, when viewed on a consumer 1080p display.

For me, this is not just an academic exercise. Our station is about to embark on a decision for HD production that will be hard to change once it's made. Do we go 720p for production, editing, and storage, assuming we have oversampling acquisition cameras? Or are we better off to use 1080i throughout the entire production chain, and convert to 720p at the emission encoder?

Once we jump one way, it will be hard to jump back the other way.

John


----- Original Message ----- From: "Manfredi, Albert E" <albert.e.manfredi@xxxxxxxxxx>


I didn't get that impression, for uncompressed signals. The quote is:

"In the presentation of uncompressed sequences, the delegates reported
difficulties in seeing difference between the three formats - even at a
viewing distance of 3h. But when the compressed images were shown, the
viewers did notice differences in the visibility of compression
artefacts."




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