What is Digg?108 Comments
- Cojawfee, on 10/12/2007, -4/+72Here is something simpler:
X's are loaded, then Z's
Interlaced:
XXXXX
ZZZZZ
XXXXX
ZZZZZ
Progressive:
XXXXX
XXXXX
XXXXX
XXXXX
Interlaced loads one set of rows, and then another. Progressive loads all rows at once. So progressive displays more graphical information at once. - leodavinci, on 10/12/2007, -4/+64To sum it up,1080p > 1080i
- Kniggit, on 10/12/2007, -1/+25*sigh* I wish these articles would be a bit more accurate in their explanations.
1080i and 1080p have the same resolution, and technically they are either interlaced or progressive as signals, but how they're displayed depends entirely on the display technology.
Virtually all flat panel and projector controllers (i.e. LCD, Plasma, DLP, and even OLED) are inherently progressive displays. There are a few I've heard of that are capable of displaying interlaced signals within the industry, and CRTs do typically have the capability to display interlaced as well as progressive. However, the flat panel and projector controllers I mentioned are virtually all progressive capable only, so the incoming signals need to be deinterlaced if they're interlaced.
In addition, even if you can display interlaced signals on a 1080 line display, you have the problem of scaling for non-native interlaced resolutions such as 480i (NTSC) and 576i (PAL/SECAM). In short, you need to adaptively deinterlace those images and then scale. You can't really scale an interlaced signal unless you throw away half the resolution (a process called bobbing) or adaptively deinterlace it. There's an additional issue with film content. Normally, 24 frame/second progressive film content can be mapped onto 60 field/second using a process called pulldown. It essentially maps 1080 line progressive image into an interlaced signal.
And here's the real gag about 1080p: unless you're dealing with 50 frame/second or 60 frame/second content (which is extremely rare at this point outside of the video game world), the vast majority of what you'll see as film (i.e. 24 frame/second) can be carried on a 1080i signal (i.e. component cable or first-generation HDMI) with absolutely no loss in quality. The display processor of a relatively new (last 2 years) flat panel or projector normally has a film mode pulldown detector that intelligently reassembles the interlaced image back into progressive. But you could also get one that does "pseudo-1080" deinterlacing by using the bob method described above.
So, be careful how the article says that 1080i is *displayed* as interlaced. Virtually all 1080i you'll see is displayed progressively either by motion adaptive deinterlacing, or turned into 540p first and then scaled up with loss of quality on older panels. - craterburnsu, on 10/12/2007, -1/+16@Ebeniz
It's an PAL Related Guide, In Europe it's 50, USA (NTSC) 60. - pixelperfect, on 10/12/2007, -1/+16Good article for the already in the know crowd (diggers) but ...
I have tried to explain all of this to many people and it is surprising how most people don't get it - it is frustrating.
As for interlacing.. it was a solution to a very very old problem that is not need now with our technology.
I hate it when we need to support old standards for ever.. - pouwerkerk, on 10/12/2007, -0/+13http://en.wikipedia.org/wiki/1080i#1080i_vs_1080p
- Hale, on 10/12/2007, -1/+14HD-DVD also supports 1080p, not just Blu-Ray.
- Ebeniz, on 10/12/2007, -1/+14there's no such thing a Pal HD and NTSC HD... it's all HD
- dmerc, on 10/12/2007, -2/+13720p if there's action.
- nowisee, on 10/12/2007, -2/+13720p > 1080i
Why are they still using interlaced video? - Kniggit, on 10/12/2007, -0/+10Yep. The BBC transmitter in London has been transmitting H.264 test streams in HD for a while now. I've had a hell of a time trying to play back some of those captures because the tools to deal with H.264 embedded in the standard transport stream format but it's doable. I'm actually glad that Europe is going to H.264 fairly rapidly because MPEG-2 requires double the bandwidth for the equivalent peak SNR, especially for sports.
- dobesov, on 10/12/2007, -0/+10@Kniggit
I think you have that backwards. The whole point of interlacing is that you get a fake 60 fps from 30 FPS. Since every frame is really two frames interlaced at a 30 fps signal, interlacing provides double the images.
Something not mentioned in this article was that part of the reason that interlacing was created was that video does not look good progressively at a real 30 fps it lacks the motion blurring that is created with chemical film so a higher frame rate is needed to look naturally fluid. This problem persists in our modern era of video games. Essentially to make a game look fluid 1080p need to be 60fps where 1080i only needs to be 30 fps. 1080i was created as part of the HDTV standard because of its lower bandwidth. 1080i and 720p have almost the same broadcast bandwidth because progressive runs at 60 FPS, which also means they have to capture it at 60 FPS.
Traditionally interlaced and progressive have been reserved for the mediums which they suit. Movies which are filmed progressively, so to speak, run at 24 FPS but because of motion blur look very fluid. Video which needs its 60 FPS goes interlaced o get the most out of the signal. Don't expect to be watching a 1080p TV station on your new TV, the bandwidth is too high as well as there would need to be an all new really expensive capture device.
The whole 1080p movie crazy is almost silly, since if you consider what happens when you play a 24fps film in a 30 fps interlaced mode, the interlaced frame is composed of one whole full resolution frame of the movie. Its not quite the same as progressive, but I doubt that most people would be able to tell the difference. - cbreaker, on 10/12/2007, -0/+9You're very wrong. When you talk about TV signals you're always talking vertical resolution. 576i does have 576 pixels vertically, but only 720 pixels horizontally. It's not a wide screen specification. 720p is 1280x720, full 16x9. There's twice the pixels in 720p.
To do wide screen on 576i you have to use anamorphic pixels; meaning the horizontal pixels are not square, but rectangular. In the end, you have a much better picture with 720p (and twice the resolution of 720p with 1080, which is 1920x1080.) - dmr0240, on 10/12/2007, -1/+9Actually, p is better than i.
- tuxthepenguin, on 10/12/2007, -0/+7Wow..... Am I the only one who still uses a TV manufactured in 1980's?
- dextius, on 10/12/2007, -0/+6EXACTLY... we won't be seeing broadcast 1080p for a LOOONG time, and 720p is just fine for games for now... (heck, i have a wii, and 480p is fine with me)
- Jozer99, on 10/12/2007, -0/+5The extra 45 lines that aren't displayed on analog TV are used for
1. Giving the electron beam time to reset to the top of the screen
2. Extra room for closed captioning data and such. - reddevil3, on 10/12/2007, -2/+7720p = better for motion. So that's why it's a standard for the Xbox 360 (gaming requires fast motion), and FOX and ABC also broadcast in 720p (since they mostly show sports)
- bradleyland, on 10/12/2007, -2/+6It's not just about field and frame data. For motion video, 720p (or progressive scan in general) is generally prefered to 1080i. Also, keep in mind that there is no such thing as a 1080i television set these days. All DLP, LCD RP, plasma, and LCD FP displays are progressive scan, so the interlaced signal must be deinterlaced. This is where the artifacting and inaccuracies come in. The more the motion, the bigger the challenge.
- Kniggit, on 10/12/2007, -2/+6@pixelperfect:
1080i deinterlacing is one of the biggest consumers of bandwidth in modern image processors in digital displays as well as silicon area. I truly wish the standard had not included interlaced (at least 1080p30 as opposed to 1080i60) because it is one of the biggest problems in image processing today and actually has increased the cost of all digital displays while simultaneously reducing the image quality. - catchneyez, on 10/12/2007, -0/+4You know 720p may be better than 1080i in theory, but I've tried every game I own on the Xbox 360 in both formats and 1080i always seems to look a little bit better.
- alephsmith, on 10/12/2007, -1/+5@Ebeniz
Two main formats IN AMERICA.
Over here in Australia they are still legally allowed to call 576p HDTV, not E(xtended)D(efinition)TV. - dukeeeey, on 10/12/2007, -1/+4Let me exlain,
A 1080i picture implies there are 2 pictures (fields) taken at different periods of time, then displayed at the same time on the screen. This is a catrastrophe really for HDTV screens (all being progressive) because you need to find some decent way of deinterlacing the picture. Most of the time the only 100% fool proof method is to simply blend the fields together which can result in ghosting and always takes the edge off the sharpness in the picture. But it is very tricky, because on a TV station there will often be a mixture of progressive and interlaced material so often everything ends up being deinterlaced regardless of whether the picture is interlaced or not.
Just because your stream is 1080i doesn't mean it is actually interlaced. It is a real shame that HDTV is still often still interlaced. It means the cameras they use SUCK. It is a bandwidth issue, its easier for the camera to transmit 1 field in 1/50th of a second then a full frame every 1/25th of a second (for PAL).
To convert video from PAL to NTSC or vice versa, they do it by ..... *shock* interlacing it. It looks fine on an interlaced screen. But on a progressive screen convert material looks shocking frankly. - dmerc, on 10/12/2007, -1/+4It's not that easy. For a setup that can up-convert 720p progressively, the picture will be better than 1080i for certain shows (like action stuff). But Yes, 1080p is the best right now.
To sum it up, it depends. - rstarr, on 10/12/2007, -0/+3I always hear the 1080i vs 720p argument for video games...
...but I never hear the clear winner....?
- UnnDunn, on 10/12/2007, -3/+6The article doesn't talk about how ALL digital displays (Plasma, LCD) deinterlace everything, making the difference between 1080i and p only a matter of framerate.
Only CRT monitors display interlaced images. - ChefGroovy, on 10/12/2007, -0/+3My tv has a wood cabinet and sits on the floort. Two knobs one of vhf one for uhf. Pretty old school. Have to shake the knob to get it to work sometimes. The corner by the screen all rainbowed cause its been too close to the speaker for the past 30 years. Had a newer piece of crap sitting on top of, but it died pretty quick.
Goes with my mp3 player with a crank on the side and a big horn. j/k - Kniggit, on 10/12/2007, -3/+6Just so you know, 720p/768p screens are good enough at standard viewing distances of 6+ ft. for screen sizes up to 37". In other words, you cannot tell 1080p unless you're running a computer output or are sitting at an abnormally close viewing distance (less than a foot). From there, 1080p starts becoming noticeable around 60". Are YOU going to be buying a >60" display?
Also, all broadcast infrastructure and cameras currently handle 1080p60 at a maximum. HD-DVD and Blu-Ray are 1080p max. I challenge you to name one single common consumer source that is greater resolution.
What this WILL be used for is in professional applications, such as financial institutions that require incredible amounts of information to be simultaneously displayed. But this will all be driven by computers, and consumer electronics will NOT benefit in any way because of this for the vast majority of consumers. - sintaxi, on 10/12/2007, -0/+3"Only CRT monitors display interlaced images."
If the signal is interlaced. One set of lines changes then the next. What is so hard to understand? - Kniggit, on 10/12/2007, -0/+3@dobesov:
You're right about the frame rate. In fact, we were working on motion compensated frame rate conversion for TVs to eliminate the judder/blur problems that happen in flat panels. They currently deinterlace and do add/drop frame rate conversion to repeat every reassembled frame from the deinterlacer which isn't the best way to deal with the judder problem (that was sarcasm, btw).
However (and I've said this many times to others) the 24 frames per second of film is critical to its suspension of reality for the viewer. I've seen what film turned into video using advanced motion compensation techniques looks like, and it doesn't look like film any more. The judder problem is distracting, but film look is inherently ruined because judder doesn't typically exist every second of a film.
I do realize that gaming has that issue, and I know that there are 120Hz conversion products coming shortly, with even 240Hz further on the roadmap (that's flat panels that update at 240Hz!), but the sole reason is to ultimately give a smoother viewing experience when you need it. I won't begin to tell you the memory bandwidth problems that motion comp frc solutions like this have, but it isn't pretty. Read my other posts and I actually mention these exceptions. - Arkz, on 10/12/2007, -0/+3Enhanced not Extended alephsmith
- lateralus, on 10/12/2007, -1/+3and 1080i if you plan to only view the title screen.
- DigitAl56K, on 10/12/2007, -2/+4A lot of the comments here aren't actually very informative.
1080i usually means 60 fields per second. You get the full vertical resolution of 1080 lines, but only half the lines are updated every 60th of a second (alternate lines, not top and bottom half of the screen!).
1080p usually means 30 frames per second. You get the full vertical resolution of 1080 lines, but it's only updated once every 30th of a second.
The benefit of working with progressive is that you always get the full instantaneos picture. Unless you have a CRT which is actually designed to scan out the picture in an interlaced fashion, progessive is nicer because it's extremely difficult to de-interlace back to progressive well (remember that for every progressive frame you have to combine two interlaced fields shot 1/60th of a second apart). Progressive also compresses better.
The benefit of interlace, however, is that motion seems far more fluid because the picture is updated twice as frequently. Until we get to 1080p60, 1080i will still be better for things like sports content for this reason. - wunch, on 10/12/2007, -0/+2When the numbers and letters are the same, you should be comparing color accuracy and contrast, which is arguably even more important, and should probably even be looked at first. (but I get that you're trying to keep it simple :)
- dcarpenter85, on 10/12/2007, -0/+2Another question that has been bugging me forever-
Why are most lcd tv's 1366x768 when 720p is 1280x720? Why scale the 1280x720 signal at all when you could display it natively in 1280x720... I just dont get it. 1080p televisions run at 1920x1080... so what is the deal with 1366x768? - Broccoli, on 10/12/2007, -2/+4But does it make a differnce if you are using an lcd tv because those dont scan.
- cbreaker, on 10/12/2007, -0/+2dobesov: No. 1080i isn't 30 frames a second, it's 60 half frames a second. There's a big difference because there can be spacial differences between each interlacing frame.
- JesusDeluxe, on 10/12/2007, -1/+3good quick read - cleared up a few things for me
- chadamir, on 10/12/2007, -2/+4BBC and sky 1 have been airing 1080p H264 at higher bitrates than the US airs 1080i mpeg2 =/
- davenport651, on 10/12/2007, -0/+2The good 80s televisions were built like tanks! I'm using a cheap TV from the 90s. Just one coaxial input for the antenna. I'll be using this TV until it dies, then i'll buy a used SDTV from the pawn shop. I've seen some really nice HD televisions and the picture looks phenominal, but I decided that for the two hours per day that I watch TV, I can stand to look at a low resolution picture.
- Kniggit, on 10/12/2007, -0/+2@mplex:
I met Yves Faroudja last year at a conference. He's a small older fellow but very nice and friendly. Just so you know, however, the pulldown was exactly what I was talking about. A 24 frame/second source can be mapped onto interlaced. In fact, DVD's use this precise principle both on the encode side (i.e. Repeat First Field flag in the MPEG stream) as well as the decode side. That's why a $25 DVD player has no fancy deinterlacer but can reassemble the interlaced output into true progressive (480p). This won't work with true 60 field/second video content, however.
However, Mr. Faroudja is absolutely right - deinterlacing is a heuristically solved problem that will never be fully solved because there is inherently no closed form solution (outside of pulldown) and imperfect information about its origination. That is, of course, UNLESS the maker of the interlaced material uses progressive segmented frame (where the two fields are captured at the same time and simply weaved together by the display device). Then again, that's not really interlaced any more... - cbreaker, on 10/12/2007, -2/+4Film indeed has an inherent high resolution, but not higher then the cameras they're using in Hollywood now. Almost everything is HD, usually 1920x1080 in some sort of film frame rate like 24FPS. Star Wars (the new ones) and almost every other movie hitting the theaters these days is done with HD Cams. Film is very expensive to use.
There is a big "high definition" gap between the late 70's and the mid-90's. Most television was recorded during that time using NTSC or PAL camcorders. Before that, it was film, and after that it's been moving towards HD. That's why we get HD versions of Knight Rider (which was recorded in Film) but we'll never get HD Facts of Life. Not that you'd want it anyways.
HDV *is* MPEG2. It's not glorified in any way. It's a trade-off - You can only fit so much data onto a tape, and you can only cost so much for a consumer device. HDV is very good if you ask me. It's not uncompressed HD but I think it looks great on my FX1.
Ohh, and yea. HD-DVD and Blu-Ray use your "***** MPEG2." I ***** you not. They just use higher bit rates because the discs hold a lot more then a standard DVD. For a good quality output to a DVD disc, look at DiVX or XVid or H.263. At high resolutions and high bit rates these codecs are incredible.
ps. All HD broadcasts also use "***** MPEG2." - Chesterfield, on 10/12/2007, -0/+2@cbreaker wrote:
"Film indeed has an inherent high resolution, but not higher then the cameras they're using in Hollywood now. Almost everything is HD, usually 1920x1080 in some sort of film frame rate like 24FPS. Star Wars (the new ones) and almost every other movie hitting the theaters these days is done with HD Cams. Film is very expensive to use."
That's crap.
I've worked on a few major motion pictures that were shot on film because it's cheaper. Why?
1: The typical HD 1920x1080 technology is natively far inferior to film. The resolution is not the issue ( it's a hair under the 2048 horizontal lines of a typical film scan), it's the color depth and contrast range. A film negative has a huge dynamic range. The chips are not there yet.
2: Those that do shoot with off-the-shelf HD need to rent film-look lenses and light for film anyways.
3: The post-pipeline to get the HD material up to acceptable color and contrast standards require every shot to be post-treated, bringing the cost at the back end way up.
4: Hundreds of film labs are ramping up for digital, but for now, the mainstream directors still shoot film because they know, and are comfotable with the process and the infrastructure is still in place for film. The digital intermediate process allows them to take full advantage of films vast dynamic range.
5: They can now rent the 2K and 4K digital film-back cameras (Superman, Apocolypto, Flyboys were shot with the Panavision Genesis camera) which were engineered to shoot like the cameras that veteran DPs are used to. These are not typical HD cameras!
Lucas had Sony completely re-engineer HD technology for the new Star Wars films and was shooting straight from the chip into massive and fast hard drive arrays (at the time, he was the only one shooting with it)
Read American Cinematographer or equivalent to see which films were shot HD.
Colateral, starring Tom Cruise, was shot with the Thompson Viper camera, The look is special because the digital chip was sensitive enough to capture
the LA skyline at night.
The choice for now is still film because it's what Hollywood knows, and until the theaters go to digital projection, they still have to make release prints (which, by the way, are often inferior to digital because of the lack of quality control, projection standards, etc.) - dukem72, on 10/12/2007, -0/+2So a if an LCD set tells you that it's resolution is 1368x768, then that equates to? Can someone explain this please.
- cbreaker, on 10/12/2007, -0/+1What? What part makes you think I don't understand? I probably have more background on the subject then you do, working for the broadcast industry and all..
- cbreaker, on 10/12/2007, -0/+1I think it has; for projector TV's these days you're hard pressed to find a 720p set. They're almost all 1080 now. And, most sets also accept and display a full 1080p signal, useful if you connect a computer. Plasma displays on the other hand have a hard time with 1080 on smaller TV's because plasma pixels are hard to make that small. That's why you generally only see 1080 on the 60" plasmas or above.
720p is a fine resolution but I definitely prefer 1080 when possible. For TV, and depending on the output device, 720p looks great. Plasma TV's make 720 look really nice since they have more of a "crt" look to them then say, an LCD. - dobesov, on 10/12/2007, -0/+1@Kniggit
Oh, and I would like to apologize, because I realized that your were talking about internal bandwidth, where I was speaking of external AKA Broadcast/rendering/signal/storage bandwidth. I was thinking of transferring of information from one location to another like on the internet, over the airwaves rather than say your TVs internal memory. Would de-interlacing not be more of a computational power issue than a bandwidth issue on the internals of the TV? I have a hard time understanding that the problem is shifting information around inside, rather than actually preforming the calculations in time. - Thmstec, on 10/12/2007, -1/+2Kniggit, challenge taken. There are countless digital cameras which do well over 1920x1080. In 16:9 mode mine does 2816x1584 (4.5mp). Would be really nice to have some other option than the 30inch Apple and Dell displays to see these high-res shots near-native. And it won't be long (or so i hope) that we get the RED camera, which does 2540p for $17,500. (red.com)
- mplex, on 10/12/2007, -1/+2From what I understand, 24fps film does not map perfectly to 60hz/fps and 3:2 pulldown is the best solution for dealing with the problem. There are serious motion problems with interlaced video. To quote someone with much more knowledge on the subject on 1080i, “I am amazed that anybody would consider launching new services based on interlace. I have spent all of my life working on conversion from interlace to progressive. Now that I have sold my successful company, I can tell you the truth: interlace to progressive does not work!” - Yves Faroudja
- warnergt, on 10/12/2007, -0/+1I'd like to know where people get the notion that only CRTs can display interlaced video. You can independently update the odd and even lines of an LCD display, too.
-
Show 51 - 100 of 106 discussions
Check out the new & improved 
© Digg Inc. 2009
— Content created and posted by Digg users is