OTA 1080p vs cable 720p?

[roger1818]

Originally Posted by ota_canuck

720p is said to be Softer?

I think the complaint is CBC's 720p is softer. That is because they master all their programming at 1080i (not 1080p) and then convert it to 720p for up-link, so they are getting the worst of both formats. If they mastered their programming at 720p (or better yet 1080p) then the picture would be much better.

[JamesK]

I recall a chart mentioned here a couple of years ago, about the distance at which you could distinguish between 720 & 1080 for various screen sizes. If you're close enough to see the difference, it will seem "softer" no matter what the source. Also, the CBC is still using very low resolution video for some remote news shots. Those ones look like they took a letterbox image from SD and zoomed it. You don't have to watch the news very long before seeing examples of that.

BTW, aren't some movies now shot at 2160? With that resolution, it's possible to produce both 1080 and 720 video without interpolation. Conversion simply requires averaging over 2 or 3 lines.

[roger1818]

Originally Posted by JamesK

There are still 1080 lines. They're just updated 30 times per second with have of them being updated with field at 60 Hz rate.

For still images that is true, but when there is motion, the object will have moved when it draws the second half frame, so everything looks blurry (as if it only has 540 lines).

[roger1818]

Originally Posted by ota_canuck

The guy in this video sums it up pretty good!
http://www.youtube.com/watch?v=Z-JXfyvlPh0

I had a look at this, and it is pretty good, though he completely ignores de-interlacing, assuming the TV will make every other line black. However, most TVs will do at least some de-interlacing with some better than others. Almost all TVs will do 2-3 pull down detection and inverse telecene to restore movies back to their original 24 frames/s, removing all motion artifacts and giving you all 1080 lines of resolution each and every frame.

When inverse telecene is not possible, most TVs will do some type of field extension de-interlacing (each of which will produce some type of viable artifact) but some will perform motion detection to minimize if not eliminate these artifacts, resulting in an amazing 1080p image. Motion compensation requires significant processing power, thus only higher end TVs typically have it.

[ota_canuck]

roger1818,

CRTs&projections vs Flatscreens?

Older CRTs&projection TVs were designed to optimize the interlaced lines. Flatscreen are designed to optimize progressive scanned lines.

I think the guy in that video was insinuating that all flat screen 720p/1080p HDTV displays are created somewhat equal and are designed to work best with a progressive content input. CRT's and projection TVs may have more difficulty handling interlaced content inputs. I'm not sure if that is true, but thats where I thought his explanation was headed.

[holl_ands]

Perceived resolution depends a lot on the material, how activity is stressing the MPEG
compression and the processing in the HDTV.

A few years ago, LCD manufacturers were making a big deal about 1080p processing,
which was a GOOD THING, cuz many of the older 720/768p LCDs were throwing away
every other frame in a 1080i signal, resulting in 540p....which was clearly lower rez
than 720p.

Meanwhile, those of us with 1080i capable Plasmas with 1080p internal processing
were happily watching the best that 1080i broadcasts could provide. Which was
clearly superior to 720p for more or less stationary images (nature etc). And
of course, these sets could readily process 720p signals, so active sports programs
weren't degraded (presuming Cable Box is set up to output BOTH formats).

Modern HDTVs, with even BETTER adaptive motion interpolation and other
algorithms with faster processors and more memory are better than ever:
http://en.wikipedia.org/wiki/HDTV_blur
http://neuron2.net/LVG/interlacing.html
http://www.100fps.com/

So be very careful WHEN these alleged "tests" were conducted and HOW they were
displayed. Many of them were from the early dark ages of HDTVs....

Unfortunately, the SOURCE material is very rarely even CLOSE to what it COULD be,
due to a variety of problems, including transcoding from cameras to editing suites,
compressing and transcoding again for transmission via Satellites and perhaps yet
again for final delivery to the user.....

[roger1818]

Originally Posted by ota_canuck

CRTs&projections vs Flatscreens?

For all intensive purposes, CRTs & projection TVs are dead and it isn't worth bringing how they handle content up.

I think the guy in that video was insinuating that all flat screen 720p/1080p HDTV displays are created somewhat equal and are designed to work best with a progressive content input.

That is my point and it is a false assumption. A cheap flatscreen TV will do very little de-interlacing, where as a higher end one may do an amazing job. It all depends if they do motion compensation de-interlacing and how good an algorithm they use.