[opendtv] Re: Some results - 1080p @ 60 is Next?
- From: "Manfredi, Albert E" <albert.e.manfredi@xxxxxxxxxx>
- To: <opendtv@xxxxxxxxxxxxx>
- Date: Fri, 4 May 2007 18:07:22 -0400
John Shutt wrote:
> What does it say in the third paragraph on page 4 of the 8 page PDF
> you quoted from in the above?
> (Hint: it says "In the demonstration, we first showed six sequences
> in uncompressed form (1080p/50, 720p/50 and 1080i/25).")
Immediately after that last quote you show above, on Page 4, it says:
"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."
This means that when they were comparing the uncompressed formats, there
was no noticeable difference. But when compressed, the differences
started showing up.
This is not at all the same as saying that "even when uncompressed, 720p
was preferred."
>> 1. If your acquisition is 1080p or 720p, you should use
>> 720p transmission.
>>
>> 2. If your acquisition is 1080i, then you should use 1080i
>> transmission.
>>
>> 3. And furthermore, going to 1080i or 1080p acquisition is
>> the right decision for the future. Preferably, of course, 1080p.
>
> Your conclusions are the opposite of the EBU findings, keeping in
> mind that theirs was a demonstration, not an exhaustive study.
Not really. And the reason is, all the EBU comparisons were made with
1080p acquisition only. Which means that part of what I wrote above
falls outside of the boundaries of their test.
In a nutshell, here's what appears to be the real deal, going from the
EBU *and* the Mark Schubin findings:
If you acquire at 1080i, then your best bet is to deinterlace directly
to 1080p and bypass that 720p step. But since 1080p is not an approved
ATSC transmission format, your best bet is to go all the way to the
receiver with 1080i, and let it deinterlace to its native 1080p format.
On the other hand, if you acquire at 1080p or at 720p, then transmitting
at 720p makes it easier to reduce the transmission bit rates at or below
16 or 13 Mb/s, without introducing as many artifacts.
And lastly, 1080i acquisition does give you improved results compared
with 720p acquisition, at least when the results are displayed at 1080p
or 1080i. I have no information on how these compare on a 720p display.
Bert
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