The Glade 4.0 :: View topic - HD Source resolutions (Poll)

Lenas wrote:

Not true. If a TV has a refresh rate of 60hz, it's always moving at 60hz. To display 30fps on a TV with a 60hz refresh, each frame is repeated 2 times every 30th of a second. TV's don't look for changes in the frames before they do anything.

You don't understand.

With a CRT, the redrawing of the screen was necessary. The pixels on the screen stopped glowing in tiny fractions of a second if they weren't being hit by that electron gun.

On an LCD, to actually redraw a screen, all pixels have to be turned off, then turned on again. The pixels are all represented by an individual transistor that is either on, or off. (actually, by several transistors that are on or off, to account for color as well, but that gets complicated, so we'll keep it simple.)

A 120Hz refresh rate on an LCD monitor just indicates that it can change the value of the transistors controlling that pixel 120 times in a second. However, it does not do so, unless the actual value of that pixel is supposed to change 120 times in a second. If a particular pixel is to remain white for several seconds because the scene on the screen is not changing, then the pixel simply stays on the entire time. The LCD television does not redraw it at all. To do so would actually lower image quality, since it would introduce an imperceptible flicker as the pixel rapidly shut off and on again. It would also be less accurate, as the pixel would shut off while it was still supposed to be on, and a liquid crystal display can remain in its same state indefinitely without needing a redraw.

LCD screen changes are "incremental" because parts that don't change do not need to be redrawn -- to do so would be a bad thing. A static image is just that -- a static image. The TV is not so stupid as to turn the picture off and on again when it's not changing. The refresh rate of an LCD monitor, at least for non-interlaced resolutions, only indicates the speed at which the screen can adjust individual pixels. The concept of "refresh" is really a misleading term to use on them. Switches that are already on do not get turned off and back on again, nor can they be turned on when they are already on.

Many high-end LCD televisions now have a 120 or 240 Hz (current and former NTSC countries) or 100 or 200 Hz (PAL/SECAM countries) refresh rate. The rate of 120 was chosen as the least common multiple of 24 frame/s (cinema) and 30 frame/s (NTSC TV), and allows for less distortion when movies are viewed due to the elimination of telecine (3:2 pulldown). These higher refresh rates are most effective from a 24p-source video output (e.g. Blu-ray Disc), and/or scenes of fast motion.

The refresh rate is the number of times in a second that display hardware draws the data. This is distinct from the measure of frame rate in that the refresh rate includes the repeated drawing of identical frames, while frame rate measures how often a video source can feed an entire frame of new data to a display.

Most TV sets today refresh the picture either 50 times per second (50Hz) or 60 times per second (60Hz) depending where in the world you live (different regions use different color formatting.) That rate is fine for most images, but when it comes to fast moving shows like sports events the images can appear blurry on an LCD (liquid crystal display) TV. Doubling the rate at which images are displayed, to 100 or 120 frames per second, makes for a better, more high-definition picture.

Author:	Kaffis Mark V [ Thu Oct 14, 2010 1:08 pm ]
Post subject:	HD Source resolutions (Poll)
Answer in the generic; that is, not necessarily tuned directly to your own home setup, but from a standpoint of what (failing 1080p) you'd prefer broadcasters and content providers adopt and offer. Which do you prefer on a source (cable/satellite feed, optical media, streaming source, etc.), and why? Please feel free to further qualify in reply posts and expound on how that qualification affects your choice, or just explain what lead you to select the choice you did.

Author:	Müs [ Thu Oct 14, 2010 1:34 pm ]
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720p is plenty. i is for chumps.

Author:	Lenas [ Thu Oct 14, 2010 1:58 pm ]
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My understanding is that interlacing isn't too great for fast-moving visuals. A lot of what I watch in HD is fast, so I'd prefer 720p.

Author:	Sasandra [ Thu Oct 14, 2010 2:14 pm ]
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Well to me 1080i deinterlaced to display on a 1080p TV always looks to result in a bit sharper of an image than 720p interpolated up to 1080p and on a 720p TV a 720p signal does look better than a 1080i, but since almost all HDTV's now are 1080p I picked 1080i.

Author:	Khross [ Thu Oct 14, 2010 2:43 pm ]
Post subject:	Re: HD Source resolutions (Poll)
Ummmm ... Really? How does your TV make a full 1080p image out of 2 frames with scan lines that run at 30 hz? Does it reduce it to a 15 hz 1920x1080 series of images? Or does it simply show the same frame 4 times in a row and pretend to be 60 hz?

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HD Source resolutions (Poll) https://gladerebooted.net/viewtopic.php?f=5&t=4425	Page 1 of 2

Author:	Sasandra [ Thu Oct 14, 2010 3:31 pm ]
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1080i is 60Hz, deinterlaced it's essentially 1080p at 30Hz, 720p is of course 60Hz and thus still 60Hz when displayed on a 1080p display but the resulting frames aren't as clear since it was scaled up and no mater how good the software is a scaled picture never looks as sharp and clear as the original source. And seeing as things like movies are only even recorded at 24Hz 30Hz really is more than adequate thanks to motion blurring in TV broadcasts and movies.

Author:	Talya [ Thu Oct 14, 2010 7:19 pm ]
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720p is more than clear enough. I really don't notice much difference between a 720p broadcast and even a 1080p blu-ray unless I sit very close to my television. I can't say I've seen 1080i. Note, however, that Blu-Ray movies are 24fps, so a 60fps interlaced image is still enough to keep up with blu-ray frames with a little room to spare. Doesn't mean it will look good...I remember interlace resolutions on old CRT monitors, and while I'm sure there are differences, I'm skeptical.

Author:	darksiege [ Thu Oct 14, 2010 7:48 pm ]
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I voted for "Farsky is standard def" Mainly because I do not give a rats *. I plug my Living room TV in with the HDMI plug from my TV Provider and the HDMI plug from my PS3. I plug my Bedroom TV in via the COmposite plugs from my Cable Co. and the HDMI to my XBox 360. It looks a ** load better than the TV in I had before getting an HDTV. I plug the thing in it looks awesome. That is all I care about. My Bedroom TV is 720p my Living Room is 1080p. Can I tell the two TVs apart? only as far as one is 42" and one is 30"

Author:	Taskiss [ Thu Oct 14, 2010 9:40 pm ]
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If you have a good 120 Hz system, go for the 1080i input, otherwise go for the 720p I never knew Mr Ski was deaf....

Author:	Khross [ Fri Oct 15, 2010 7:07 am ]
Post subject:	Re: HD Source resolutions (Poll)
1080i comes in 25, 30, and 60 hz flavors. The broadcast flavor is 30hz in the U.S. unless otherwise specified by the content provider.

Author:	Screeling [ Fri Oct 15, 2010 7:37 am ]
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"Farskee is standard def" = "Farskee is gay" ? I'm confused.

Author:	Taskiss [ Fri Oct 15, 2010 7:45 am ]
Post subject:	Re: HD Source resolutions (Poll)
Khross wrote: 1080i comes in 25, 30, and 60 hz flavors. The broadcast flavor is 30hz in the U.S. unless otherwise specified by the content provider. I was talking about the TV

Author:	Khross [ Fri Oct 15, 2010 7:57 am ]
Post subject:	Re: HD Source resolutions (Poll)
Doesn't matter how big your TV is if the DVP sucks balls when it comes to de-interlacing, which is more sets than not, Taskiss.

Author:	Taskiss [ Fri Oct 15, 2010 8:06 am ]
Post subject:	Re: HD Source resolutions (Poll)
Khross wrote: Doesn't matter how big your TV is if the DVP sucks balls when it comes to de-interlacing, which is more sets than not, Taskiss. On a good tv, motion interpolation and motion blur tech will add frames and eliminate any perceived difference between 1080i and 1080p (yes, yes, YMMV), that makes the choice effectively between 1080 and 720

Author:	Sasandra [ Fri Oct 15, 2010 3:27 pm ]
Post subject:	Re:
FarSky wrote: Uh, the standard framerate in Europe is 25fps. oops, yeah, you're right, they are 50Hz 25fps there, regardless though it's most definitely 60Hz 30fps here not 30Hz 15fps.

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Author:	Sasandra [ Fri Oct 15, 2010 12:31 pm ]
Post subject:	Re: HD Source resolutions (Poll)
Khross wrote: 1080i comes in 25, 30, and 60 hz flavors. The broadcast flavor is 30hz in the U.S. unless otherwise specified by the content provider. Actually, no, both in the US and europe the broadcasting standard for 1080i is 60hz, in europe however they call it 1080i/30 denoting the fps, each frame is comprised of 2 cycle, totaling 60hz, if it was only 30hz it would only be displaying 15 frames a second which would be very jerky.

Author:	FarSky [ Fri Oct 15, 2010 12:34 pm ]
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Uh, the standard framerate in Europe is 25fps.

Author:	Müs [ Fri Oct 15, 2010 12:39 pm ]
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Yeh. PAL /= NTSC

Author:	Lenas [ Fri Oct 15, 2010 12:47 pm ]
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Let's not confuse refresh rates with frame rates.

Author:	Talya [ Fri Oct 15, 2010 2:16 pm ]
Post subject:	Re:
Lenas wrote: Let's not confuse refresh rates with frame rates. With a CRT, you'd be right. Higher refresh rates actually improved the visual quality independant of the framerates. On an LCD, the two are really the same. No matter how high the "refresh" rate of the LCD is, it generally does not redraw the screen until it receives a new frame. Conversely, no matter how quickly new frames can be sent, the actual framerate on an LCD or CRT alike, cannot exceed the refresh rate. (Turning off "v-sync" on a computer is cheating.) The LCD never really "redraws" the screen. It simply checks each frame for changes to the previous frame, and alters it accordingly, turning individual pixels on or off as needed. (of course, sometimes a frame is entirely different, so it does, in a defacto way, redraw the entire screen because the entire screen is now different.) Now, interlaced resolutions may be an exception to this. I would imagine --if designed correctly-- a high-refresh rate television was provided with the two separate portions of an "interlaced frame", it would alternate the two as rapidly as possible in order to provide as clear an image as possible, until a new paired "interlaced frame" was sent to it. That said, I have never looked into how interlaced resolutions work on an HDTV.

Author:	Lenas [ Fri Oct 15, 2010 2:26 pm ]
Post subject:	Re: Re:
Talya wrote: On an LCD, the two are really the same. No matter how high the "refresh" rate of the LCD is, it generally does not redraw the screen until it receives a new frame. Not true. If a TV has a refresh rate of 60hz, it's always moving at 60hz. To display 30fps on a TV with a 60hz refresh, each frame is repeated 2 times every 30th of a second. TV's don't look for changes in the frames before they do anything.

Author:	Talya [ Fri Oct 15, 2010 2:52 pm ]
Post subject:	Re: Re:
Lenas wrote: Not true. If a TV has a refresh rate of 60hz, it's always moving at 60hz. To display 30fps on a TV with a 60hz refresh, each frame is repeated 2 times every 30th of a second. TV's don't look for changes in the frames before they do anything. You don't understand. With a CRT, the redrawing of the screen was necessary. The pixels on the screen stopped glowing in tiny fractions of a second if they weren't being hit by that electron gun. On an LCD, to actually redraw a screen, all pixels have to be turned off, then turned on again. The pixels are all represented by an individual transistor that is either on, or off. (actually, by several transistors that are on or off, to account for color as well, but that gets complicated, so we'll keep it simple.) A 120Hz refresh rate on an LCD monitor just indicates that it can change the value of the transistors controlling that pixel 120 times in a second. However, it does not do so, unless the actual value of that pixel is supposed to change 120 times in a second. If a particular pixel is to remain white for several seconds because the scene on the screen is not changing, then the pixel simply stays on the entire time. The LCD television does not redraw it at all. To do so would actually lower image quality, since it would introduce an imperceptible flicker as the pixel rapidly shut off and on again. It would also be less accurate, as the pixel would shut off while it was still supposed to be on, and a liquid crystal display can remain in its same state indefinitely without needing a redraw. LCD screen changes are "incremental" because parts that don't change do not need to be redrawn -- to do so would be a bad thing. A static image is just that -- a static image. The TV is not so stupid as to turn the picture off and on again when it's not changing. The refresh rate of an LCD monitor, at least for non-interlaced resolutions, only indicates the speed at which the screen can adjust individual pixels. The concept of "refresh" is really a misleading term to use on them. Switches that are already on do not get turned off and back on again, nor can they be turned on when they are already on.

Author:	darksiege [ Sat Oct 16, 2010 12:32 am ]
Post subject:
I still stand by plug the bastard in and get an awesome picture. Everything else is superfluous.

Author:	Caleria [ Mon Oct 18, 2010 12:41 am ]
Post subject:	Re: Re:
Talya wrote: Lenas wrote: Not true. If a TV has a refresh rate of 60hz, it's always moving at 60hz. To display 30fps on a TV with a 60hz refresh, each frame is repeated 2 times every 30th of a second. TV's don't look for changes in the frames before they do anything. You don't understand. With a CRT, the redrawing of the screen was necessary. The pixels on the screen stopped glowing in tiny fractions of a second if they weren't being hit by that electron gun. On an LCD, to actually redraw a screen, all pixels have to be turned off, then turned on again. The pixels are all represented by an individual transistor that is either on, or off. (actually, by several transistors that are on or off, to account for color as well, but that gets complicated, so we'll keep it simple.) A 120Hz refresh rate on an LCD monitor just indicates that it can change the value of the transistors controlling that pixel 120 times in a second. However, it does not do so, unless the actual value of that pixel is supposed to change 120 times in a second. If a particular pixel is to remain white for several seconds because the scene on the screen is not changing, then the pixel simply stays on the entire time. The LCD television does not redraw it at all. To do so would actually lower image quality, since it would introduce an imperceptible flicker as the pixel rapidly shut off and on again. It would also be less accurate, as the pixel would shut off while it was still supposed to be on, and a liquid crystal display can remain in its same state indefinitely without needing a redraw. LCD screen changes are "incremental" because parts that don't change do not need to be redrawn -- to do so would be a bad thing. A static image is just that -- a static image. The TV is not so stupid as to turn the picture off and on again when it's not changing. The refresh rate of an LCD monitor, at least for non-interlaced resolutions, only indicates the speed at which the screen can adjust individual pixels. The concept of "refresh" is really a misleading term to use on them. Switches that are already on do not get turned off and back on again, nor can they be turned on when they are already on. 120 Hz LCD displays are 120 Hz for a reason. They display each frame (assuming a 24 fps Bluray movie) 5 times within each 24th of a second. This is in an effort to eliminate motion blur. Yes, the image may not actually change that often, but it doesn't change the fact that it is being displayed and/or updated faster than 24 fps. I totally get what you are saying, it doesn't necessarily re-draw the entire screen, unless the particular frame it is displaying requires it to do so. But that doesn't change the fact that the TV is attempting to update the image at a faster rate than traditional 24 fps. And the 120 Hz / 240 Hz technology TV's were made specifically to eliminate a problem with lower refresh rates. So you can't really say that refresh rates and fps are the same thing in LCD TV's because a 24 fps movie really is displayed at 120 Hz. Yes, there are still only 24 separate frames displayed every second, but they are being displayed multiple times, depending on the refresh rate. Wikipedia wrote: Many high-end LCD televisions now have a 120 or 240 Hz (current and former NTSC countries) or 100 or 200 Hz (PAL/SECAM countries) refresh rate. The rate of 120 was chosen as the least common multiple of 24 frame/s (cinema) and 30 frame/s (NTSC TV), and allows for less distortion when movies are viewed due to the elimination of telecine (3:2 pulldown). These higher refresh rates are most effective from a 24p-source video output (e.g. Blu-ray Disc), and/or scenes of fast motion. from the same wiki article: Quote: The refresh rate is the number of times in a second that display hardware draws the data. This is distinct from the measure of frame rate in that the refresh rate includes the repeated drawing of identical frames, while frame rate measures how often a video source can feed an entire frame of new data to a display. And another one for good measure: PC World article wrote: Most TV sets today refresh the picture either 50 times per second (50Hz) or 60 times per second (60Hz) depending where in the world you live (different regions use different color formatting.) That rate is fine for most images, but when it comes to fast moving shows like sports events the images can appear blurry on an LCD (liquid crystal display) TV. Doubling the rate at which images are displayed, to 100 or 120 frames per second, makes for a better, more high-definition picture.

Author:	Talya [ Mon Oct 18, 2010 1:22 pm ]
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I understand everything you said there. Of course when viewing at 1080p from a Blu-Ray disk, 120Hz would not appear any different than a theoretical 24Hz LCD, even during fast action scenes. 120Hz IS slightly different than 60Hz, simply because 60Hz displays a marginally uneven frame-rate from a 24fps source. (each frame has time to be "redrawn" 2.5 times, which in reality becomes twice for one frame, three times for the next.) Interlaced resolutions would be far more affected by LCD refresh rate. So are video games, and faster video sources, if they existed, would only be marginally better. (It's unnecessary. Actual camera work captures motion blur, making 24fps appear just as good as 600 fps...your brain isn't going to be able to tell the difference.) 60Hz LCDs would benefit from a variable refresh rate that allowed them to slow down to an exact multiple of the source feed.