[mythtv-users] OT: Why 1080p?

[Rich West]

While motion does play a role, all video streams, regardless of their
content, are made up of different speeds of motion within the video.  In
other words, you get both normal and fast motion with nearly everything
out there aside from looking at still images on the screen.

Personally, I don't believe what the ads try to push..

Anyhow, while this has diverged waaay off topic for this list, try
shooting a couple of queries to google to get some excellent write-ups.

http://alvyray.com/DigitalTV/Naming_Proposal.htm was one that I came
across a while back that had a good summary:
"Interlacers often claim that their system has more pixels. See
bandwidths for the actual numbers. Summary: It is not the pixels in a
still frame that counts - still video is boring. It is the pixels per
second delivered to viewers that matters. The 540I system, /as defined/,
delivers only slightly more pixels per second than 720P, and, /as
practiced/, it delivers less! This, of course, is before compression. As
argued above, what matters to consumers is after compression. After
compression, the formats are indistinguishable so far as pixel count is
concerned. However, the interlaced system is fundamentally flawed
because of its flickering, which does not go away during compression."

While movie theaters display at 24fps, NTSC is 29.97 frames per second,
which includes TV transmissions, video tapes, DVDs, etc. (a nice write
up can be found at http://www.daniele.ch/school/30vs60/30vs60_1.html,
among other sources).

-Rich


Daniel Kristjansson wrote:
> On Tue, 2006-11-07 at 13:14 -0500, Rich West wrote:
>   
>> 1080i is technically lesser quality than 720p.
>>     
>
> This is just wrong.
>
> The long answer is that 720p is has higher vertical but lower horizontal
> resolution when displaying high motion, think basketball. For movies and
> low motion sports, think baseball and football, 1080i is better. This is
> because 720p is 720 lines at 60 frames per second, while 1080i is the
> is 1080 lines at 30 frames per second. Movies are only 24 frames per
> second, so they will always look better in 1080i. Basketball and tennis
> are high motion sports so they are filmed at 60 frames per second and
> benefit from being shown at the lower resolution and higher frame-rate
> of 720p.
>
> People are confused about this because in modelines:
>   1080i at 60fields-per-second = 540p at 60frames-per-second
> but the two odd and even lines of 1080i do not sample
> the same region of the image so this is also true:
>   1080i at 60fields-per-second = 1080p at 30frames-per-second
>
> Also, the networks that only broadcast in 720p (FOX & ABC), run lots of
> ads saying 720p is better. Unfortunately this is just a bald faced lie
> which they perpetuate so that people don't complain about how crappy
> movies and baseball look on those networks. They broadcast at 720p
> because the lower resolution format requires less bandwidth, so they
> can put crappy extra channels in the extra space. PBS also adds
> crappy channels while broadcasting at 1080i, but they get MPEG artifacts
> due to the too low bit-rate they allow for their 1080i stream.
>
> -- Daniel
>