Can YOU Tell the Difference ?

[Seeker47]

. . . between a 1080i and a 720p picture ? (To try to level this out, let's assume reasonably good reception of reasonably good Cable / Sat / OTA, on reasonably good equipment that is reasonably well adjusted.) If so, what are some tell-tale things to look for ? I'm guessing maybe things like strands of hair, or beard whiskers, or skin pores on close ups . . . but then I don't really know. So far, these sorts of things, and things like water moving around in a swimming pool, seem to illustrate the huge difference of HD over 480i, to me.

[Heywould3]

its hard to tell because lcd tvs are progressive so a 1080i picture will be converted to a P signal not 1080P but to the tvs native resolution. that being said. i can tell the difference. and it is minimal to me.. a 720P signal will have full detail and stay clear even durring motion. a 1080I picture will have what looks like slightly better clearity but when there is movement. the areas that move will have slight blurr to them. like in a football game. the grass will stay clear while the players will blurr very slightly.

[Ollie6431]

. . . between a 1080i and a 720p picture ?

I watch HDTV on a 50''DLP-projection TV with 1080i (1st generation). Comparing channels with known specs (720p vs. 1080i), I (subjectively) see better resolution with 1080i channels. I have heard different ideas from others, however. It is like comparing apples with oranges (?)

[lordsmurf]

It depends on more factors. How well was the source encoded or broadcast? What is the size and quality of the viewing device?

Don't be a measurebator (hats off to Ken Rockwell, great term).

[edDV]

Heywould3 has it on motion. The amount of motion blur or clarity of the grass depends on the quality of the HDTV source, processing and display resolution.

For even a perfect TV, the motion precision of 720p/59.94 will always be noticed for sports, the added low motion clarity of 1080i disappears as you add distance from the TV. Most people sit too far back from a TV for 1080i to make a difference.

If you are on cable or DBS, most 720p/59.94 gets converted to 1080i/29.97 eliminating the motion advantage.

[Coolpplse]

For MPEG2 HD Broadcasts 720p always maintains the image quality within this resolution due to the heavily aging MPEG2 codec, with 1080i all the static scenes seem to give an edge over 720p in detail, when it comes to medium to high motion the image quality drops dramatically with very heavy macroblocking not only because its interlaced but the fact that all HD Broadcasts are stuck at the lame 19mbps with the aging MPEG2, 720p seems to be the only resolution that does not produce this very inconsistent quality jump from scene to scene.

[Seeker47]

Heywould3 has it on motion. The amount of motion blur or clarity of the grass depends on the quality of the HDTV source, processing and display resolution.

For even a perfect TV, the motion precision of 720p/59.94 will always be noticed for sports, the added low motion clarity of 1080i disappears as you add distance from the TV. Most people sit too far back from a TV for 1080i to make a difference.

If you are on cable or DBS, most 720p/59.94 gets converted to 1080i/29.97 eliminating the motion advantage.

Yes, it's cable. Exactly where and when does this conversion occur ? Not at the source: I believe the set is natively a 720p device; for any channel coming in, a button press on the remote brings up a window reporting whether what is being watched is 480i, 1080i, or 720p.

It won't make any difference to me with this set, but is my impression correct that there is currently very little transmission of 1080p content ? That is the standard or the capability most loudly being touted, but if it is really as scarce as I think it is, this tends to fall into the area of deceptive hype.

[Seeker47]

For MPEG2 HD Broadcasts 720p always maintains the image quality within this resolution due to the heavily aging MPEG2 codec, with 1080i all the static scenes seem to give an edge over 720p in detail, when it comes to medium to high motion the image quality drops dramatically with very heavy macroblocking not only because its interlaced but the fact that all HD Broadcasts are stuck at the lame 19mbps with the aging MPEG2, 720p seems to be the only resolution that does not produce this very inconsistent quality jump from scene to scene.

When you say "heavily aging MPEG2 codec", this suggests to me that we are being hoodwinked with some very transitory standard that may be obsoleted in just a few short years (if not already), leaving us holding the bag . . . . (?) I'm not gonna sweat it, because I got 20 years out of that CRT -- it don't owe me nothin' ! -- and the LCD I just bought cost me only about a hundred bucks more than I paid for the other CRT eleven years ago. But, if I'm reading you right, I sure would have a problem sinking the major $$ into a good plasma panel or HT setup, if all we're doing is chasing old news.

[edDV]

Heywould3 has it on motion. The amount of motion blur or clarity of the grass depends on the quality of the HDTV source, processing and display resolution.

For even a perfect TV, the motion precision of 720p/59.94 will always be noticed for sports, the added low motion clarity of 1080i disappears as you add distance from the TV. Most people sit too far back from a TV for 1080i to make a difference.

If you are on cable or DBS, most 720p/59.94 gets converted to 1080i/29.97 eliminating the motion advantage.

Yes, it's cable. Exactly where and when does this conversion occur ? Not at the source: I believe the set is naively a 720p device; for any channel coming in, a button press on the remote brings up a window reporting whether what is being watched is 480i, 1080i, or 720p.

It won't make any difference to me with this set, but is my impression correct that there is currently very little transmission of 1080p content ? That is the standard or the capability most loudly being touted, but if it is really as scarce as I think it is, this tends to fall into the area of deceptive hype.

Back to basics:

First over the air ATSC digital broadcasting in the USA:

The local broadcaster gets to decide which of the 18 ATSC formats he will broadcast on his primary channel. Sub-channels can be any of the 18 ATSC formats or just digital data streams*.
Nobody is currently broadcasting 1080p/23.976.
http://www.hdtvprimer.com/ISSUES/what_is_ATSC.html

The major broadcast networks have chosen their primary broadcast standard. All have chosen 1080i/29.97 for primary channel except ABC and FOX that specialize in sports programming:

ABC 720p/59.94
Fox 720p/59.94

PBS sends programming to the local channel as 1080i/29.97 but some stations convert this to 720p/59.94 at lower bitrate on the primary channel so that 2 additional 480i/29.97 channels can be broadcast as subchannels.

A plasma or LCD HDTV will receive all these channels and convert all to the TVs native progressive panel resolution (1024x768, 1366x768, 1920x1080 typical). ABC or FOX 720p/59.94 direct sports or live broadcasts will show full motion detail that 720p/59.94 broadcasting can achieve. PBS converted broadcasts which create 720p/59.94 from a deinterlace and resize from 1080i will not have the full crisp motion.

Cable/DBS boxes:

Local cable channels are usually distributed over cable in the same format as broadcast but are modulated QAM and bit rate may differ from over the air.

Cable networks usually uplink HD broadcasts as 1920x1080i/29.97 but some use 1280x720p/59.94 (e.g. ESPN) and some use 1280x720p/29.97 (choppy motion) or even 1280x720p/23.976 (film rate).

Set top tuner boxes operate in several modes for HD.

1. Most HD boxes make you choose one standard to the TV (480i/480p/720p/1080i). 480i is there for normal TV sets and 480p is there for EDTV sets.

If you choose 720p, all 1080i programming is deinterlaced and rescaled to 1280x720p/59.94 in the cable box. 720p programming will be passed as is**. A plasma or LCD HDTV will then scale 1280x720p input to native display resolution.

If you choose 1080i, all 720p programming is upscaled and interlaced to 1920x1080i/29.97 and progressive motion advantages of 720p are lost. A plasma or LCD HDTV will then deinterlace the 1080i and scale to native display resolution.

2. Some HD boxes also offer a pass-though HD mode where 720p channels are passed as 720p and 1080i channels are passed as 1080i. This is what you want for a newer plasma or LCD-TV which can change standards on the fly but this won't work for early some TV chipsets or for CRT or some projection HDTV sets.

3. Irregardless of the set top tuner, some newer HDTV sets can direct tune QAM (clear) or use Cablecard to decrypt other cable channels. If you have a plasma or LCD-TV with QAM tuner it is often better to direct tune the local ABC or FOX channel to view 720p/59.94 in all it's glory thus avoiding the conversions in the cable box. On some cable systems ESPN-HD1/HD2 are also available as Clear QAM for high quality viewing.


* Direct digital stream options can be anything including WMV-HD, H.264, VC-1, Divx-HD or whatever the local station chooses to broadcast so long as the primary channel is one of the 18 ATSC choices.

** except for 720p/29.97 or 720p/23.976 which will be converted to 720p/59.94

[edDV]

For MPEG2 HD Broadcasts 720p always maintains the image quality within this resolution due to the heavily aging MPEG2 codec, with 1080i all the static scenes seem to give an edge over 720p in detail, when it comes to medium to high motion the image quality drops dramatically with very heavy macroblocking not only because its interlaced but the fact that all HD Broadcasts are stuck at the lame 19mbps with the aging MPEG2, 720p seems to be the only resolution that does not produce this very inconsistent quality jump from scene to scene.

When you say "heavily aging MPEG2 codec",

He is just making an inside baseball editorial comment about the future transition to MPeg4/VC-1/other. This mostly means you will need a new cable box when cable internally changes to AVC.

The ATSC standards groups are looking at adding MPeg4 or other formats to the 18 standards listed but that will be years out and not initially affect the primary broadcast channel.

[edDV]

...
It won't make any difference to me with this set, but is my impression correct that there is currently very little transmission of 1080p content ? That is the standard or the capability most loudly being touted, but if it is really as scarce as I think it is, this tends to fall into the area of deceptive hype.

1080p is only available on some not all Blu-Ray or HD DVD players @12-25Mb/s (depending on codec).

1080p HDTV panels are sometimes capable of being driven at 1080p/60 over a computer interface but that has nothing to do with TV.

TV comes in three basic flavors these days

1080i/29.97 at 14-19Mb/s
720p/59.97 at 12-19Mb/s
480i/29.97 at 2-9 Mb/s

I'm leaving out camcorders for now.

It would be possible for some entrepreneur to buy a local ATSC independent TV station and start broadcasting movies at 1920x1080p/23.976 19Mb/s but very few TV sets would be capable of reliable reception and the vast majority of those that could would first convert it to 1080i/29.97 so what's the point.

A more logical business model would be to broadcast QVC or something on the primary channel and VC-1 or Divx-HD on a subchannel with reception by subscription decoder boxes connected HDMI. This is currently being done in SD with analog connection for TV pay movie delivery to hotels and motels.

[Seeker47]

It is all a bit confusing, but that helped. Thanks for all that clarification.

2. Some HD boxes also offer a pass-though HD mode where 720p channels are passed as 720p and 1080i channels are passed as 1080i. This is what you want for a newer plasma or LCD-TV which can change standards on the fly

This is the way it seems to be with this new LCD / setup.

3. Irregardless of the set top tuner, some newer HDTV sets can direct tune QAM (clear) or use Cablecard to decrypt other cable channels. If you have a plasma or LCD-TV with QAM tuner it is often better to direct tune the local ABC or FOX channel to view 720p/59.94 in all it's glory thus avoiding the conversions in the cable box. On some cable systems ESPN-HD1/HD2 are also available as Clear QAM for high quality viewing.

The latter does not appear to be an option. The roof antenna (or its wiring entering the bldg.) is shot, and is unlikely to be replaced. I've been auditioning possible inside alternatives -- just as a backup -- but so far no joy.

After what you said, I can see that there are plenty of provider variables. For example, several national programs from the CW network (the merged remnant of UPN and the WB) begin with the "HD" logo. That seems to be useless in this market though, because the local CW station does not have an HD channel on our Time Warner . . . although most of the other local stations do. So those CW programs can only be viewed as 480i. One might think this would put them at a big competitive disadvantage, however (for all I know) they might have such an HD version of their channel on Cox, or DirecTV.

[edDV]

A couple of things. Who is your cable provider and which HD cable box do they offer? I'm familiar with Comcast and Time Warner and the Motorola and Scientific Atlanta HD cable boxes. All the boxes I've seen lock you to 1080i or 720p unless you switch manually.

Second, I was talking about direct QAM tuning on the cable to get ABC, FOX or ESPN. This bypasses the cable box quirks but your HDTV needs QAM tuner capability.

All that is separate from over the air ATSC tuning although that is always option 3.


RE:CW
CW HD carriage is negotiated between Viacom/WB and your cable provider. If the station fell into "must carry" status, your cable company is required by the FCC to pass the HD broadcast as QAM if the station puts it on air in HD. The same station may only show as analog over the cable box.
http://en.wikipedia.org/wiki/Must-carry

This is one reason you should buy a HDTV that has QAM tuning.

[Seeker47]

A couple of things. Who is your cable provider and which HD cable box do they offer? I'm familiar with Comcast and Time Warner and the Motorola and Scientific Atlanta HD cable boxes. All the boxes I've seen lock you to 1080i or 720p unless you switch manually.
This is one reason you should buy a HDTV that has QAM tuning.

Oh, thought I'd said, but it is Time Warner. The box is a Motorola DCH3200. They said this was the current next-to-top -of the-line they are offering, as I was looking for Component and HDMI Out, but no HD-DVR.

Second, I was talking about direct QAM tuning on the cable to get ABC, FOX or ESPN. This bypasses the cable box quirks but your HDTV needs QAM tuner capability.

All that is separate from over the air ATSC tuning although that is always option 3.

I thought this LCD had both, but I'll need to confirm that.

RE:CW
CW HD carriage is negotiated between Viacom/WB and your cable provider. If the station fell into "must carry" status, your cable company is required by the FCC to pass the HD broadcast as QAM if the station puts it on air in HD. The same station may only show as analog over the cable box.
http://en.wikipedia.org/wiki/Must-carry

That was just a handy example (of which there are probably other similar cases, for anyone reading this). It seems pretty clear that TW does not carry this station as HD in this market, whatever the reason. I can only guess that their OTA broadcast is HD -- at least during primetime -- otherwise their showing the "In HD" logo becomes nonsensical.

[edDV]

Not clear from the specs whether the Motorola DCH3200 auto switches but one way to test it is to switch channels on the cable box from NBC to FOX to CBS to ABC and see if the TV responds 1080i - 720p -1080i - 720p. Also see what the TV reports for ESPN and PBS.
http://broadband.motorola.com/catalog/productdetail.asp?ProductID=518

QAM tuning needs to be actively set up and scanned. See your TV manual.

CW is a "retransmission consent" station which means Viacom (CBS) needs to negotiate an HD channel position for CW. It looks like Viacom chose instead to throw its weight to getting the MHD (MTV+VH1+CMT) HD music channel on Comcast and Time Warner.

If CW was a "must carry" station (like ION), the cable company would be required to offer the channel with HD as clear QAM and as analog on the cable box.