De-interlacing and scaling the most important buying factors?
By Darren Murph 
posted Jan 14th 2007 3:55AM
posted Jan 14th 2007 3:55AM
While the whole "1080i vs. 1080p" debate could likely go on for a good decade or so, having that oh-so-coveted "Full HD" logo slapped on your set evidently isn't the answer to all your HD problems, at least if you watch a good percentage of cable / satellite-provided content. A rather informative writeup / rant over at HD1080i lends a bit more insight into the ongoing discussion of when 1080p differs from 1080i, and goes on to explain that many incorrectly processed images cause quite a bit of dissatisfaction when it comes to quality, and oftentimes, it's not even your fault. Sure, folks outputting 1080p from an HD DVD or Blu-ray player get the benefit of seeing a progressive, pre-cleaned-up image, which basically removes all the hard work from your TV's internal scaler; however, for those watching a processed episode of TNT HD's Charmed, for instance, could witness a bit of "interlacing crop errors when de-interlacing is not done properly," rather than just a correctly rendered motion blur. Essentially, this fellow attempts to convince us that 1080p is an important matter, and it's great to have it there "when you need it," even though it's not likely that we see 1080p content coming through our cable STB anytime soon. So be sure and hit the read link to take a gander at yet another perspective, because a bit more research never hurt anyone, eh?
since when is motion blur correct rendering of interlaced material?
Does the FCC license sufficient bandwidth in the digital realm such that a digital television broadcaster can, if they had the money and equipment, to broadcast in 1080p?
I was under the impression that the reasons why 1080i and 720p were adopted by the broadcast industry (and the consumer electronics industry) was that at the time of atsc adoption (by the FCC) the technologu wasn't available for transmitting 1080p.
Transmission of 1080p requires twice the bandwidth of 1080i, but contains the same amount of physical resolution. We are comparing 1995 technology to 2007 technology. And while most broadcasters would rather not upgrade again for the distribution of 1080p, I would think the technological means would be available.
Does anyone know if FCC licensing of a spectrum for the transmission of digital ota television includes enough bandwidth for 1080p signal transmittion? It would be much easier to introduce interlacing at the consumer than removing interlacing at the consumer. Comparing the costs between the two models (and the two parties, being the broadcasters and consumers) is worth noting.
"since when is motion blur correct rendering of interlaced material?"
Since that's what happens on his TV and he's trying to justify the costs to himself ("Yes I spent a lot, but "I" have true HD and the plebes have almost HD. "I" am therefore that much greater in comparison"
embee:
Sorry wrong. 1080p is not that pricey
I have Westerndigital LVM 37" 1080p for video editing running off an nVidia 7600 GT DVI card pair.
That Westy is 1300 bucks, no lie , go to Best Buy and ask for one, since they rarely have them out on the floor.
Personally though for 1080p right now i really like the Sony SXRD stuff around 2200 bucks at 50 inches.
I am surprised at how little people understand what 1080i is, and the conversion processing that systems undergo with the content, but its good to see that a few posters here have a decent understanding. It aint rocket science, and actually the worst issues with image quality are Macroblocking and rapid scene cut keyframe block recovery in compression with mpeg2 and mpeg 4.
I've always wondered why scaling/deinterelacing is nowhere evident in the marketing for any HD display. Not so much with scaling, but there are potentially more differences in how deinterlacing. is done.
Properly done, on a 1920 x 1080 display, a 1080i and a 1080p source signal may be impossible to visually tell apart.
Still, I am curious why a lot more emphasis/testing of deinterlacing is done on fixed pixel displays.
Sometimes 1080i@60 video is generated by 3-2 pulldown from film that was shot at 24 fps. Obviously a 24p format would be optimal. It would be slightly cheaper in bandwidth to send that material at 1080p@24. The 1080i version has more fields but the codec can also see more redundant material between the fields since the "real" frames are 24ths of a second apart, not 60ths.
riverside_guy, currently the people who are aware of deinterlacing issues are the ones who also know which chips or chip sets do the best job of overcoming them, so you'll see the names of the deinterlacing chips in the literature for the displays or whatever component does the deinterlacing. You'll also see the chips mentioned on forums like www.avsforum.com. I'd mention the name of one of the most prominent but I can't spell it reliably. Also, you'll see such trademarks as the AVM ones used by Fujitsu and PureCinema used by Pioneer. You could also google for "chroma bug" to learn about a problem that occurs in decoding interlaced MPEG video. I've seen the chroma bug and it can really mangle red objects under the right circumstances. The issue is discussed and documented all over the place, but at the moment it might not be done at an accessible, novice-friendly level.
Ghostdoggy, No, the FCC does not provide bandwidth for 1080p, as it is not part of the ATSC standard. However, this is not a problem.
For MOST 1080i60 material, the source is 1080p24. This means that the 1080i60 signal actually contains the ENTIRE 1080p24 source folded within it via 2:3 cadencing and interlacing. With proper de-interlacing of a OTA 1080i60 program that was encoded from a 1080p24 source, your TV can actually display the TRUE, REAL, FULL RESOLUTION of the 1080p24 source in glorious 1080p... again, assuming your TV can de-interlace properly, which is a big assumption.
The point is though, that the onus is on the TV manufacturers to make monitors and TVs with good scaling and deinterlacing built-in, then we won't need to change the ATSC spec to include broadcasting of 1080p.
1080p24 is readily available over the air RIGHT NOW. We just need the deinterlacers capable of displaying it, and the TV's capable of processing the full bandwidth of a 1080p signal.
MOST tv shows except for most sports and talk shows are 1080p24 source material. No lie. Virtually ALL movies broadcast on tv are 1080p24 source (i.e. they were film, then they were telecined to 1080p24 for digital archival, then they get broadcast in 1080i60.)