720 vs. 1080 debate

[Richard Firnges]

Hallo Graeme,

to make it clear: I definetly prefer progressive over interlaced, that is out of question. But I see for the MOMENT a better perspective for 1080i as an IINTERMEDIATE step to 1080p.
When I compare DVB – S oder DVB T with DVDs I definetly see large differences in picture quality. If You only count pixels the should be none. Broadcasters tend to sacrifice datarate (quality) for more Channels (The call it „content“). I have seen DVB – T broadcasts that have had VCD –Quality. Even most DVDs You can buy are sloppy encoded if You stretch SD to its limits. And that is the main reason I argue for a bigger format: Providers (TV Stations and Disc Providers) tend to be sloppy, because sloppy usually means cheap. If You have a system that is actually too big for most uses, at least You don’t suffer too much as a consumer under this sloppiness. If You watch a very good DVD and compare it with the usual TV - broadcast (analog or digital) you will see a big difference. I think it will be the same with HDTV. Most of the people in this forum work with good equipment and try to produce good quality. But the question is, what will be delivered to the consumer. As an engineer I know that it is easier to archive „good“ results in „rich“ environments. To do the same thing within a smaller frame needs much more skill. For this reason in consumer reality the difference between progressive and interlaced, 720p or 1080i is more academic than of real meaning. Ouf course there will be oustanding products but the average will be 50 % under the possible limit....
That may sound silly, but we need the bigger format to compensate for the sloppiness of the providers. Therefore I would prefer to wait until 1080p is feasible or accept 1080i as an intermediate format that makes migration to 1080p easier

Richard

[Graeme Nattress]

But 720p, being more compact (and 1080i having no more real vertical detail) does compress easier than 1080i, and hence will provide a better picture in the home for the same data rate.

Indeed, a bigger format will mean more compression and less quality to the viewers at home. And 1080i takes more data than 720p but does not offer any real, meaningful quality improvement due to interlace being a very sloppy form of compression.

Personally, I'd argue that using MPEG2, you'd get a better image, overall giving 10mbps to and SD broadcast (anamorphic widescreen, of course) over twice that datarate (ie 20mbps) to a 1080 HD broadcast, and 90% of people would benefit from the improved SD picture (ie, those who don't have an HDTV). As you say, many SD digital broadcasts are VCD quality, and quite frankly, that's not acceptable, but by the same argument, an over compressed HD image would be better replaced for the vast majority of viewers by improved SD broadcasts at full DVD maximum quality.

Graeme

[Barry Green]

Originally Posted by Graeme Nattress

But.... 24p is part of the HDTV specifications, is it not, so that a broadcaster could send out 24p as whole frames now and not have to add pulldown frames??

720/24p and 1080/24p are both accepted broadcast standards as defined by the ATSC.

[Steve Crisdale]

Originally Posted by Graeme Nattress

Personally, I'd argue that using MPEG2, you'd get a better image, overall giving 10mbps to and SD broadcast (anamorphic widescreen, of course) over twice that datarate (ie 20mbps) to a 1080 HD broadcast, and 90% of people would benefit from the improved SD picture (ie, those who don't have an HDTV). As you say, many SD digital broadcasts are VCD quality, and quite frankly, that's not acceptable, but by the same argument, an over compressed HD image would be better replaced for the vast majority of viewers by improved SD broadcasts at full DVD maximum quality.

Graeme

That's the dilemma that Australia now faces. We have a current Parliamentary committee looking into the 'Slow uptake of Digital TV'.

It's becoming very clear, that if the broadcasters - for whatever reason ends up being used to justify their actions - degrade the data-rate to the point where consumers (not afficiandos) can't see a verifiable advantage to DTV; let alone HDTV, purchases of 'old technology' display units will continue.

Without the display units capable of displaying even the level of 1080i in the majority of a nation's homes, why would any DTV provider worry about pandering to the outcries from the Early Adopters, when those precious few who can, perceive how poor the service being provided has become. Early HD broadcasts here in Oz looked amazing, because the signal stream was being pumped much closer to the full data-rate... but that has gradually changed, with piggy-backed program streams and the data streams and interconnectivity for those with the appropriate STB and hand controller... Band width after all is something the broadcasters have paid for, so they need a commercial return.

The average Joe out there doesn't give a deuce of rat's droppings about how good the game looks on his analog set that he "ain't gonna sell 'cause some smarmy suited sales-guy tells me this is better than what you got at the moment....sir". He does want to see all the news and sports results running across the bottom or top of screen though... so the broadcaster provides that service for them, and as part of the bandwidth allocation, that extra stream has to come from somewhere.

Strangely enough, advertisers want to put their money where the greatest return is, and while we HD early adopters may honestly believe that's us!... I got news.... It ain't us. Until the percentage of TV owning homes that have HDTV displays is around the 40>50% mark, HD technology advances will most likely tread water, or be incrementally added. 1080p would be one of the last elements to be implemented, and it's viability to the majority of TV viewing households even if/when 1080i capability reaches saturation would be even more doubtful.

The fact is... some parts of the HD video delivery chain are far more advanced than others, and that seems to accent the gap between the links that like our HDV camera capabilities, cost, options and availability; represent HD acceptance and above expectation realization of outcome... while the uptake of DTV and HDTV display devices represents the completely converse.

Until the 'average' consumer has a HDTV set up in their lounge, we who argue about the advantage of 720p over 1080i and vice-versa will provide entertainment value for visitors to the forum; but it'll be as relevant to reality as much political debate is, i.e. Diddly-squat relevance!!

I believe those who presently own a HDV camcorder have an opportunity to at least circumvent one of the major qualifiers being thrown about as a reason for poor PQ and data-rates of Aussie DTV/HDTV. "Not enough HD content" is the most common anthem being trumpetted. Well, if they have the content because HD10u or FX-1/Z1 shooters are providing it, they ain't got no excuse.

So rather than huff and puff about is 720p or 1080i better... how's about shooting HDV regardless of whether it's 1080 or 720 and get the stuff to a broad-bloody-caster and maybe the HD revolution can be truly ascribed to the abilities of those who realised the promise. Nah... what am I thinking!! George Lucas, or maybe Jimmy Cameron deserve the sole credit for the HD viewing revolution... because they're visionaries!!!

[Richard Firnges]

Of course at the moment 720p (especially with 24 or 25 fps for movie broadcast) is more feasible then 1080 (i or p). If we take MPEG2 Pal - DVDs for example: You need bitrates between 6 and 8 mbs (without sound) for the best quality. So the bitrate of the FX1 which works with 25 mbs is in the same area. For full 1080 at 25 fps you need therefore at least 30 mbs bandwith (or more). For 720 with 25p ( not 50p!) the equivalent would be 15 mbs. So from this point you are probably getting a better overall picture with 720 if you only consider broadcast bandwidth. But there will also be disc storage like blue ray. And for this kind of media the storage of 1080 movies ist doable.
I for myself doubt that TV stations are really willing to provide quality (That‘s why I gave up watching movies on TV). Not even in 720p. The don‘t do it today in SD, why should they do it in HDTV? In comparison their „HDTV“ probably would‘t be much better than the best anamorphic SD from DVDs. So from a practical point of view Broadcast - TV will always be inferior to discs (or whatever the media will be). Of course it will be better than broadcast SD....

But on discs we can have in a foreseeable future enough storage room for the high bitrates. Downconvering is always easier than the other way Therefore wie should aim now for the larger picture. With a large enough frame and a high enough bitrate we would have a system where don’t work on the limits. An we shold never forget that als existing movies are 24p, so 720p with 50 or 60 fps is not the optimum since the higher timeresolution is not needed.

Greetings Richard

[Shannon Rawls]

the HVX200 should have eliminated this discussion.

*smile*

- Shannon W. Rawls

[Steve Crisdale]

Originally Posted by Shannon Rawls

the HVX200 should have eliminated this discussion.

*smile*

- Shannon W. Rawls

Are you saying Shannon, that the HVX200 would have settled the arguement of which is beyond any doubt, reasoning or blind faith, the superior format?

Isn't that a little like saying science should have settled the discussion on evolution? ;)

Besides; you know how much fun it is to watch all the different reactions to something that gets posted!! :)

If there weren't followers of either camp... imagine how dull it would be around here!!

[Shannon Rawls]

Originally Posted by Steve Crisdale

Besides; you know how much fun it is to watch all the different reactions to something that gets posted!! :)

HA!! ain't that the truth! *smile*

I'm sayin the HVX200 will allow people to have the best of both worlds. *CHEESE*

Mercedes Benz or BMW???

Nobody could decide which was better, so I got a Lexus. *smile*

MAC or PC???

Nobody could decide which was better, so I got em both!

720p or 1080i????

heck...just buy a HVX200!!!!

*smile*

- Shannon W. Rawls

[Tommy James]

JVC knew that when they introduced the worlds first consumer high definition video camera that there would be the naysayers who would claim that 720p is not real high definition so at the same time they introduced their line of 1500i super high definition televisions that upconvert all signals 720p and 1080i to 1500i. Note that this became the perfect compliment for JVC HD camcorders because 1440i is the native upconversion of 720p.

[Javier Gallen]

The fact is that, if you grab a frame from a movie in a 1080i HDTV, and then downsize to 720p and resize it back again to 1080i the result is two IDENTICAL images.

That makes me think...

[Ken Hodson]

Well 1080 is a bit of an anomaly in that except for the most recent CineAlta's, no cam was actually capturing that resolution. So to choose it as a broadcast standard makes little sense to me. As well all but the most recent consumer PC's had a hard time even working with footage of that high resolution. In fact if it wasn't for the archaic adoption of interlace, this format would still be largely unusable even now.
Its 2005 and we still have people trumpeting an interlaced format? Ya got me!

[Tommy James]

The reason why Sony promotes 1080i is because 1080i is a bigger number than 720p so 1080i sells more cameras. Sony's support of 1080i has nothing to do with picture quality. So far it has been a very sucessfull strategy but Sony knows that it wont be able to get away with interlace forever so soon they will start promoting 1080p.

[Javier Gallen]

The reason why Sony promotes 1080i is because 1080i is a bigger number than 720p so 1080i sells more cameras. Sony's support of 1080i has nothing to do with picture quality. So far it has been a very sucessfull strategy but Sony knows that it wont be able to get away with interlace forever so soon they will start promoting 1080p.

Good point.

Until we have 1080p, i'll be more interested on 720p.

[Thomas Smet]

Ok guys I am doing a test right now to compare 720p and 1080i. This test is in no way what to expect from specific cameras but is to give a general idea of detail with the formats.

I created a scene in 3D Studio Max with objects of fairly high detail. I then rendered as 1280x720 uncompressed and again as 1440x1080 interlaced uncompressed.

I next took those images and brought them into Shake to compare scaling results to match the footage. What I have found so far is what Graeme has been trying to say. There is almost no difference in detail between 1280x720 scaled up to 1440x1080p and 1440x1080i deinterlaced to 1080p. Depending on how you deinterlace and scale the 720p image is actually a little sharper. The 720p also has the advanatge of not having any aliased edges because of deinterlacing. Even with the sharpness the same the 1080i version has blocky edges on thin details which at least to me makes the 720p look overall slightly better. They are however very close and only the most anal engineer would be able to tell. It may even be harder to tell on an actuall TV. For film out however those steppy edges could show up a little bit more on the 1080i. 720p gives a clean even image.

At this point I would say the "only" advantage 1080i has over 720p HDV is the 60 frame per second motion. If your target is film or simulated film then this doesn't matter.

This test of course does not take into consideration lens quality and other factors that dumb up the image from the camera. If a 1/3" lens can't handle more than 1280x720 anyways then the results from this test would be even better in favor of the 720p. "If" the lens on a specific camera actually can deal with the native resolution of that camera then this test still proves there isn't much difference between the two current formats.

I will try to post results of this test later. I am currently working on a 3D resolution chart to render out the different formats.

[Kevin Dooley]

Originally Posted by Thomas Smet

At this point I would say the "only" advantage 1080i has over 720p HDV is the 60 frame per second motion.

While it has yet to be implemented in an HDV product (other than the new JVC's uncompressed outs), 720/60p is a recognized standard for HD and more specifically is called for in the HDV specs... this negates 1080i's advantage, as 720/60p should be as sharp (or sharper) than 1080/60i for the reasons you've already stated....