yeah, it is i again, here are the questions:
1) assume you have an HDTV that can display 480i, 480p, 720i, 720p and 1080i, here's what some will consider a really stupid question: why can't the tv display 1080p?
i know on the surface it appears to be a retarded question but i can't seem to find any technical reason why it would be impossible, if the tv can display both interlaced and progressive encoded content and it can display 1920x1080 interlaced then why shouldn't be able to display those same 1920x1080 pixels when they are encoded using progressive scan, it's still the same number of pixels? is it just a marketing limitation to get people to buy the more expensive 1080p sets?
2) if you have a video, say a HDTV capture that's 1920x1080i and for whatever reason you wanted it downscaled what would be the best downscaled resolution to convert to? in other words i have seen people claim that 1920x1080i is the equivalent of 960x540p, a completely absurd claim that i know is wrong yet i keep seeing it around the net and despite knowing that it's a stupid claim i can't seem to stop thinking about it every time i think about downscaling 1080i content primarily because if there is even a kernel of truth in the notion then it's ridiculous to try and convert from 1080i to 720p because then you are effectively upscaling the video, so the target should be 960x540p or lower.
3) assuming i am correct and 1920x1080i is not the same as 960x540p, then what would be the best de-interlacing method to go from 1080i to 1080p or 720p (the 1080i source shows horribly exaggerated interlacing effects when i try and play it back on my computer).
4) last but not least, what is the unit that pixels are measured in? in other words when we say we have a pixel aspect ratio of 1:1, 4:3, 16:9, what we really are saying is that the pixels are 16 units wide and 9 units tall, but what exactly is that unit? if we had a 1440x1080 4:3 video and a 720x480 4:3 pixel, would the pixels of the first file be the same size as the pixels of the second file or do they just have the same ratio? i guess fundamentally what i'm asking is when we resize a video, without cropping, are we actually resizing the pixels along with discarding some pixels or are we just discarding pixels?
thank you, come again.
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Originally Posted by deadrats
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2) if you have a video, say a HDTV capture that's 1920x1080i and for whatever reason you wanted it downscaled what would be the best downscaled resolution to convert to? in other words i have seen people claim that 1920x1080i is the equivalent of 960x540p, a completely absurd claim that i know is wrong yet i keep seeing it around the net and despite knowing that it's a stupid claim i can't seem to stop thinking about it every time i think about downscaling 1080i content primarily because if there is even a kernel of truth in the notion then it's ridiculous to try and convert from 1080i to 720p because then you are effectively upscaling the video, so the target should be 960x540p or lower.
The best resolution is the same resolution, and hopefully is the one that your TV/monitor supports natively. Displays work best at their native resolution. Any other scaling up or down will degrade the image (some hardware scalers are worse than others)
3) assuming i am correct and 1920x1080i is not the same as 960x540p, then what would be the best de-interlacing method to go from 1080i to 1080p or 720p (the 1080i source shows horribly exaggerated interlacing effects when i try and play it back on my computer).
If this is for PC display, you can use a better deinterlacer, but the good ones are too slow for real time playback (ie. instead of running it though ffdshow or through an avs script for real time playback, you usually have use an .avs script to re-encode a new file). You can experiment with a few deinterlacing modes in VLC for example, just toggle through them. But they all pale in comparison to the heavy duty avisynth methods. The quality difference is like night/day.
4) last but not least, what is the unit that pixels are measured in? in other words when we say we have a pixel aspect ratio of 1:1, 4:3, 16:9, what we really are saying is that the pixels are 16 units wide and 9 units tall, but what exactly is that unit? if we had a 1440x1080 4:3 video and a 720x480 4:3 pixel, would the pixels of the first file be the same size as the pixels of the second file or do they just have the same ratio? i guess fundamentally what i'm asking is when we resize a video, without cropping, are we actually resizing the pixels along with discarding some pixels or are we just discarding pixels?
Display Aspect Ratio = Frame Aspect Ratio x Pixel Aspect Ratio
So for your example
16/9 = 1440/1080 x 4/3
And a square pixel 1920x1080 1:1 would be:
16/9 = 1920/1080 x 1/1
Yes, when you resize, you are discarding pixels. -
Originally Posted by manono
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Originally Posted by deadrats
Actually your TV is probably scaling everything to about 5 percent bigger than 1368x768 and only showing you the center 1368x768 pixels to simulate overscan.
And, by the way, many HDTVs can display 1080p input. Mine can display video input at 1920x1080p, 60 fps or 24 fps. 24 fps is displayed at 60 fps by duplicating frames in a 3:2 repeat pattern.
Originally Posted by deadrats
The 4:3 and 16:9 ratios that are common in video are not pixel aspect ratios but display aspect ratios (the final shape of the picture that is displayed). In general, any frame size can be displayed with any display aspect ratio. The relationship is:
DAR = SAR * PAR
where DAR is the display aspect ratio, SAR is the storage aspect ratio (relative frame dimensions), and PAR is the pixel aspect ratio (the relative width:height of each pixel).
1:1 usually refers to the pixel aspect ratio. Ie, square pixels. -
Originally Posted by poisondeathray
As for what res to resize it for that particular (obsolete) TV, then 1368x768 (if that's what it really is). That way there won't be any further resizing done before it gets displayed. Of course, the resizer used makes a small difference. -
Originally Posted by deadrats
Real physical pixels on a display device are always 'square'. So when you display a video that has 'non-square pixels', a resizing conversion must be done somewhere along the way, whether it be in your DVD player, TV or software/firmware on your computer. The PAR is a convenient shorthand for saying 'when displaying this video, it must be resized horizontally:vertically in this ratio'.
At a more technical level:
Pixels as represented in a digital movie have no shape, they are just numbers, digital samples analogous to CD audio.
The PAR is really the ratio between horizontal and vertical sampling rates (samples per unit distance).
Anamorphic video ('non-square pixels') has a horizontal sampling rate that is different from the vertical one. For a given distance, you will have a different number of pixels horizontally than vertically.
Resizing means changing the sampling rate(s), changing the relative positions of the points on the 'sampling grid', requiring calculation of new sample values by interpolation, etc (which is always approximate, so quality suffers). -
Originally Posted by manono
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Originally Posted by Gavino
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ok, so assume i have a bunch of HDTV captures with a resolution of 1920x1080i, 20 Mbps, ac3 audio, mpeg-2 video and some of them display exaggerated interlacing effects when played back on a pc monitor and further assume that the subject matter is such that i can't just walk into best buy and purchase the blu-ray (basically i have a bunch of hi def music videos, including some live performances of carrie underwood performing with heart and taylor swift performing with def leppard, as well as some superbowls like the patriots/giants game) and assume i just want to get rid of those annoying interlace effects, what would be the best course of action.
note, i'm more than happy to convert to 1080p at 20 Mbps, i couldn't care less about the size of the file, i have 3 terabytes of storage and i can add another 3 terabytes for about $200, so size, in this case, doesn't matter. -
What is your playback device? Set it to 1080i output and the TV will deinterlace.
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Originally Posted by jagabo
ok, now i'm even more confused, i just checked the settings on my tv and there are no settings for setting output resolution, which means manono is 100% correct, but that leads me to this question: this is a LCD TV, which means it can be used as a computer monitor, shouldn't that also imply that it should be capable of displaying a wide variety of resolutions? could it be that those settings are only available when it's set to operate as a computer monitor?
let's ignore the tv for a second before i get a headache thinking about it, assuming i wish to play the files back only on computer, then how would you recommend i go about de-interlacing the files? -
Originally Posted by deadrats
Originally Posted by deadrats
Originally Posted by deadrats
Originally Posted by deadrats
Originally Posted by deadrats
If you insist on deinterlacing you can use the same techniques that are used for standard definition interlaced video. For telecined film you can inverse telecine back to 24 fps film frames. For interlaced video (eg, football games) you can deinterlace or bob. You may have trouble playing back 1920x1080p60 (ie, bob'd 1080i) video though. -
Even your computer software player has deinterlacers available - not very good ones, maybe, but deinterlacers all the same. So I'm not real sure why you're so gung-ho to reencode these things with the inevitable quality degradation, especially given, from all I've seen, that you're encoding skills leave a lot to be desired.
Examine the source. If 1080i and telecined, IVTC and resize. If 720p, decimate to the 'real' resolution and resize. If pure interlace, deinterlace with a good AviSynth deinterlacer and resize.
now i'm really confused, you guys just got through telling me that a HDTV will display it's native resolution and only it's native resolution, now you're telling me to set the output to 1080i? -
Originally Posted by deadrats
Problem is most computer display cards are poor sending interlace to the TV so the TV can do the deinterlace. This is true even when component analog output is used because most of the time there is a resize before D/A. This is why 1080i out of a cable box or DVD player can look much better than 1080i out of a computer.
You need to think through the full chain.
A 1080i/29.97 file played without deinterlace on a computer gets weaved to progressive, then is sent to the TV as DVI-D 1920x1080 then the TV downscales to 1366x768 (or larger for overscan). Then what you see is weaved then resized progressive. Yes it should look awful. This video should first be deinterlaced in the software player (e.g. Cyberlink or VLC) or in the display card (get PurevideoHD or AVIVO HD).
If the video file is film source, IVTC would be used instead of deinterlace. IVTC results in a a 23.976p stream. Most likely, your RCA TV won't accept that unless it is converted back to 29.97 1080i or 59.94 fps 720p. So you need to use a hardware player that will inverse telecine, or use a software player and use the TV as a computer monitor.
If your RCA TV has internal IVTC capability, then use a 1080i player like the Western Digital Media player and let the TV do the IVTC and downsize. In this mode incoming 1080i gets converted to 23.976p then is downsized to 1366x768 then frames are repeated 3 then 2 to 59.94 fps for display.Recommends: Kiva.org - Loans that change lives.
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