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Network HD: 720p vs 1080i
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January 02, 2009 | by .(JavaScript must be enabled to view this email address)
It’s a long-running debate: 720p vs. 1080i. There are plenty of people on both sides of the resolution fence, including all the major networks.
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Posted by Matthew Anton  on  01/02  at  08:09 AM

Good writeup comparing the two. I know when im gaming I like to use the 1080i

Posted by David Ripp  on  01/02  at  12:49 PM

In the Early Days of HDTV (2000) ABC and the associated networks were using 720P, but at 30 Frames refresh instead of the 60 Frames that most thought were being used.  Is it really true that they are now using 60P?

Also you did not mention that there is a great Horizontal resolution difference:
720 is 1365 pixels wide
while
1080 is 1920 pixels wide

Thanks, and I would really appreciate knowing if in fact they are really doing 60P.  The original reasoning for using 30P was to hold bandwidth for other services.

Thanks
David

Posted by Dude  on  01/02  at  02:37 PM

Are you serious? I can’t stand using my Xbox 360 at 1080i, gaming definitely looks better at 720p. So do static images, there is less ‘bounce’

Posted by Phil Lozen  on  01/02  at  05:09 PM

I too keep my Xbox set at 720p on my 720p DLP, however, every TV will be differently equipped at handling signals, and since the Xbox can output both HDMI and Component, that plays into the picture too.

As for 720p/60 vs. 30, 720p video can refresh up to 60 times a second, it’s very possibly that certain types of video may repeat frames in that 60 seconds for a frame rate of 30. I believe 720p also can achieve a frame rate of 24 but I’m not positive.

Posted by Jose  on  01/02  at  11:03 PM

Dude,

ALL Xbox 360 games are natively rendered at 720p. If you have a 720p display, of course it will look better. You are feeding an unprocessed signal. In such case, feeding 1080i makes no sense because the xbox is upscaling, breaking down the progressive signal to interlaced signal and then your TV will have to reconvert it back to 720p. Unnecessary processing causes unnecessary artifacts.

If you have a 1080p display, upscaling WILL occur no matter what to fill all 2 million pixels, either in the xbox (setting the output to 1080p/i) or your display. Unless your display can’t accept a 1080p signal, outputting 1080p from xbox would be best, not 1080i since some displays don’t de-interlace 1080i correctly and artifacts might occur.

Posted by sports guy  on  01/04  at  10:32 AM

This answers the question as to “why does fast action sports, look pixalated on the CBS network”
                    Thanks

Posted by Mike  on  01/05  at  01:42 PM

Responding to David Ripp:

ABC never broadcast @ 720p30. Thats not even an ATSC standard, and would make broadcasts of 24p material almost unwatchable. I’ve heard a few ABC stations broadcast @ 1080i (30frame/sec, 60 fields/sec) however for some odd reason.

720p is 1280 pixels wide. However, mot “720p” displays are 1365(or 1366) x 768. For some reason thats actually easier for manufactures to make (or some such reasoning, I’m foggy on that).

I for one, am a 720p backer. I’ve yet to see a really clean 1080i show on American TV. Theres always at least a bit of blockiness on camera pans or fast motion shots. MPEG cant cut it even when a channel uses its full allotted 19Mbpsm which they often don’t.

Posted by andrew ballew  on  01/05  at  01:43 PM

sports guy, this is not why your CBS feed is pixelated.  Pixelization is caused by excessive compression.  It has nothing to do with interlaced vs progressive, except in the fact that interlaced sources are much more difficult to compress effectively. 

If what you are watching from your local CBS provider is being transmitted at the full bandwith alloted by the ATSC standard, pixelization would be minimal.  More likely, your local provider is multi-casting other channels that rob bandwidth from the HD feed, or your satellite or cable provider is adding additional compression to preserve their own bandwidth.

Posted by Phil Lozen  on  01/05  at  02:02 PM

The ATSC standard for 720p covers 60, 30 and 24. However, it doesn’t mean that the networks use all of those options.

Andrew you make a great point about compression. There’s only so much room available, so depending on your local station and more so, your provider (cable, sat, etc.) you could see different levels of compression.

Posted by Ben Drawbaugh  on  01/05  at  02:30 PM

Your math is wrong. It would be true if every frame was a keyframe, but that is far from the case.

The reason why CBS pixelates so much more is because the ATSC limit of 19.3 Mbps isn’t nearly enough. This combined with many broadcasters decision to multi-cast makes it unwatchable when there is lots of movement.

Now Fox and ABC on the other hand hardly every have pixelating problems even when they do multicasting because 720p uses less throughput than 1080i.

Posted by Hou Person  on  01/05  at  02:56 PM

So why do some stations choose 720 instead of 1080?  Because it is a lot cheaper.  There is a lot “unsaid” in the article which can be very misleading.

Each major market is a “lot” different than another.  In Houston NBC, CBS, and FOX are the best, very seldom do we get macro blocking, pixel squares or bad sound, those three stations are excellent better than 95% of the time.  Out of those three the 1080s are better by a noticable margin.  ABC in Houston is a complete joke; but when they get completely off analogue maybe many of their problems can be corrected? We hope.

Posted by Funster  on  01/05  at  03:40 PM

1080 puts twice as many pixels to the eye every 30th of a second, nuff said. There is no reason why a fixed panel display can’t display every other line interlaced just like a crt.

Posted by Sports Fan  on  01/05  at  04:33 PM

I watch sports on cbs all the time and it always looks much better than fox & espn broadcasts with no perceivable difference in picture quality.  My eyes tell me I prefer 1080i to 720p even for sports viewing.

Posted by Derek  on  01/05  at  08:16 PM

1080i looks better period.  The NFL broadcasts on CBS and NBC consistently look MUCH better than games shown on FOX and ESPN.  720P is a mistake for broadcasters.

Posted by andy4theherd  on  01/05  at  09:07 PM

I watch a lot of sports. I have an Epson Home 1080 projector and a 105” screen in my basement. CBS and NBC sports broadcasts are hands down MUCH better looking than ESPN and ABC. I use an OTA antenna for the networks so compression is not the issue. I am watching ESPN with DTV.

Posted by andrew ballew  on  01/05  at  11:05 PM

andy4theherd, feel lucky to live in a market where your local stations do not multicast. 

For many markets, compression/ bandwidth is a major issue even for OTA broadcasts.  My market, Knoxville, TN, has OTA stations that are unwatchable due to excessive compression from multicasting.

Posted by Mitch Davis  on  01/06  at  08:57 AM

1080 is a much better picture than 720, it is 2x as sharp,  forget the hype over the refresh rate.  that is what very very few people say makes it better for sports.

hah! i laugh at that because it just doesn’t look good to someone with the right system, i have 60” 1080p system.  ABC/Disney and Fox programming just looks like crap.

720p is for suckers.  i really wish those networks get a clue. 1080i at least looks much better.  Wish 1080p would be picked.  Also multicasting is an issue.  stations need to limit the extra “channel” they add, and not have multiple ones which usee too much bandwidth from their OTA signal.

Posted by Matt Brundage  on  01/06  at  09:51 AM

From the article: “720p displays 720 horizontal lines…”

No, it’s VERTICAL lines. 1280 (horizontal) x 720 (vertical). Look it up.

Posted by Phil Lozen  on  01/06  at  09:58 AM

Thanks Matt for catching that. You’re absolutely right it should be vertical lines.

Posted by Dave D  on  01/06  at  11:03 AM

Fox is definately the softest image from my provider do their cameras suck ????

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