1187: "Aspect Ratio"

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Manabu
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Re: 1187: "Aspect Ratio"

Postby Manabu » Tue Mar 19, 2013 8:28 pm UTC

gmalivuk wrote:
5th Earth wrote:I'm reminded of a friend who was ripping the DVDs of a TV show onto his computer. He couldn't get the conversion from interlaced to progressive scan to come out right no matter what he did. Eventually, he figured out that the show had been deinterlaced in the incorrect order, rescaled, and then reinterlaced on the DVD, making it impossible to remove the first improper interlacing.
If it still played properly on a dvd player, I wouldn't be surprised if such a thing were done intentionally, as a form of copy protection.

It is probably is even worse on a DVD player, maybe alleviated if you see on a low resolution CRT screen. It is pure incompetence of the people who mastered the DVDs (and/or maybe from where the masters come from too). Some things are recoverable in software, like the original 24fps FILM out of a fieldblended: FILM -> Telecine -> NTSC -> Blendconversion -> PAL - Video conversion.... but others, like yours where they resized while interlaced, or things like "taking interlaced material, deinterlacing it with an absolutely terrible deinterlacer that discards every other field and interpolates the other, and coding the “progressive” result as interlaced on the DVD" are most likely irrecoverable... (more horror stories here)

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alvinhochun
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Re: 1187: "Aspect Ratio"

Postby alvinhochun » Wed Mar 20, 2013 6:29 am UTC

A bit late, but someone has to do it...

xkcd1187_letterboxed_squeezed.png
xkcd1187_letterboxed_squeezed.png (8.97 KiB) Viewed 2587 times

This work is licensed under a Creative Commons Attribution-NonCommercial 2.5 License.
Modification of an original work by Randall Munroe published on http://xkcd.com/1187/

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arthurd006_5
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Re: 1187: "Aspect Ratio"

Postby arthurd006_5 » Wed Mar 20, 2013 10:13 am UTC

rmsgrey wrote:If it helps, try thinking of the support script as the equivalent of a NASA pre-flight checklist: "rebooted?" "check" "all plugs secure?" "check" "power to all components?" "check" "tried running task manager to check whether the service runs?" "I'm not using Windows..."

Okay, so it only works if your computer fits the script, but still...

Once upon a time, people were trying to sell me virus-checker fraud, and I was trying to cooperate long enough to find out what they were selling, but my computer was to different for them to get to the end of the script.

SemisolidSnake
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Re: 1187: "Aspect Ratio"

Postby SemisolidSnake » Wed Mar 20, 2013 4:57 pm UTC

With our Comcast, I can't recall any examples of video being stretched to different aspect ratios, but, boy, is there a ton of letterboxing. And cropping. Ugh.

The most annoying scenario I've discovered recently is watching basketball. Clearly the source video is shot in HD, but they crop the ends off when they show it on the SD channels. It's impossible to see anything the guards are doing above the three point line. Basketballs just fly out of nowhere from the side of the screen. The SD video looks pretty good scaled on my 42" HDTV, though. Well, most of the channels have an "HD" counterpart, so I turn to that. Alright, there's the full shot, and I can finally see everything on the court. Oh, but it's a letterboxed 4:3 ratio stream, so now my game is both letter and pillarboxed, and I've got fat black bars all around. I can barely see what's going because everything's so small. Ass. This is probably a common occurrence, I know.

So, my TV has an option to zoom, and, if I use it, finally the video fills the whole screen. Except that it blurs so terribly that it's usually unwatchable. HD content manually zoomed looks worse than SD content that automatically scales. I just don't get it. (I imagine it's all SD resolution, and just the aspect ratio changes) Sometimes, I'll zoom it anyway. Of course, it's the TV zooming everything it's being fed from the cable box, so when I try to use the on-screen guide to search for other channels, nearly the entire guide is cropped out. Ugh.

I did come across the most hilarious boxing yet a few days ago. I was watching Frasier on the SD Hallmark channel. It's 4:3 pillarboxed by my TV as normal; looks fine. Just for absurdity, I decided to check out Hallmark's HD analog channel. Of course it's a 4:3 stream, so the TV pillarboxes it. Then the stream is letterboxed to make it "HD" like all the "HD" channels. But Frasier was shot in 4:3, so within the letterbox, the video is pillarboxed. So the end result of two pillar and one letterboxing is a tiny nugget of 4:3 video sitting in the vastness of black space that is my large HDTV. I think I woke my girlfriend up laughing at it.

xPi
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Re: 1187: "Aspect Ratio"

Postby xPi » Wed Mar 20, 2013 11:19 pm UTC

YouTubers doing Let's Plays of 4:3 console games

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Pfhorrest
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Re: 1187: "Aspect Ratio"

Postby Pfhorrest » Thu Mar 21, 2013 12:02 am UTC

I am fairly ignorant of the standards used to transmit images over conventional TV, but to my naive impression: wouldn't it be a hell of a lot simpler and solve all these goddamn problems to just transmit the image at whatever aspect ratio it was originally created, and let the receiving device scale that until one of the two dimensions was maximized and neither was exceeded, leaving the rest black? Like when you open a video of any size and aspect ratio in a media player on a computer and maximize the window? How the hell did it come to "manually" (as it were) adding extra "put black here" data to the image? I mean, I can see that back in the day when every TV set was a 4:3 CRT and all signals were analog, so you had to scale any source material to the dimensions of a standard TV feed and fill the blank areas with black. But by the time of DVDs and HDTV and digital broadcasts, what the hell? Just send the goddamn original image and let the player handle it!
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Kit.
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Re: 1187: "Aspect Ratio"

Postby Kit. » Thu Mar 21, 2013 8:05 am UTC

Pfhorrest wrote:But by the time of DVDs and HDTV and digital broadcasts, what the hell? Just send the goddamn original image and let the player handle it!

1. Higher per-STB costs (and when you provide millions of them, every single dollar matters). That may also include licensing costs.
2. Harder to segment the market (asking higher prices for "premium" HD content).

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Steve the Pocket
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Re: 1187: "Aspect Ratio"

Postby Steve the Pocket » Thu Mar 21, 2013 9:10 pm UTC

SemisolidSnake wrote:With our Comcast, I can't recall any examples of video being stretched to different aspect ratios, but, boy, is there a ton of letterboxing. And cropping. Ugh.

...

HD content manually zoomed looks worse than SD content that automatically scales. I just don't get it. (I imagine it's all SD resolution, and just the aspect ratio changes)

If they're providing SD content and advertising it as HD, then I'm pretty sure they're breaking the law. But they're Comcast, so their contract probably included a clause somewhere that says you're not allowed to sue them.

Pfhorrest wrote:I am fairly ignorant of the standards used to transmit images over conventional TV, but to my naive impression: wouldn't it be a hell of a lot simpler and solve all these goddamn problems to just transmit the image at whatever aspect ratio it was originally created, and let the receiving device scale that until one of the two dimensions was maximized and neither was exceeded, leaving the rest black? Like when you open a video of any size and aspect ratio in a media player on a computer and maximize the window? How the hell did it come to "manually" (as it were) adding extra "put black here" data to the image? I mean, I can see that back in the day when every TV set was a 4:3 CRT and all signals were analog, so you had to scale any source material to the dimensions of a standard TV feed and fill the blank areas with black. But by the time of DVDs and HDTV and digital broadcasts, what the hell? Just send the goddamn original image and let the player handle it!

DVD technically does that. Each individual "title" (separate data file that the player has to be able to switch between) has its own flag telling the player whether or not to stretch it out (in the case of digital output) or letterbox it (in the case of analog output). If you play a DVD on a computer program, the window will actually change size as it switches between, say, the menu and the actual movie.

With broadcast television, it would be a lot harder to make work, because you're dealing with a continuous stream. Trying to switch resolutions in mid-stream would be like trying to create a video file that changes its own resolution at some point in the middle.
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Yakk
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Re: 1187: "Aspect Ratio"

Postby Yakk » Thu Mar 21, 2013 9:19 pm UTC

Pfhorrest wrote:I am fairly ignorant of the standards used to transmit images over conventional TV, but to my naive impression: wouldn't it be a hell of a lot simpler and solve all these goddamn problems to just transmit the image at whatever aspect ratio it was originally created, and let the receiving device scale that until one of the two dimensions was maximized and neither was exceeded, leaving the rest black? Like when you open a video of any size and aspect ratio in a media player on a computer and maximize the window? How the hell did it come to "manually" (as it were) adding extra "put black here" data to the image? I mean, I can see that back in the day when every TV set was a 4:3 CRT and all signals were analog, so you had to scale any source material to the dimensions of a standard TV feed and fill the blank areas with black. But by the time of DVDs and HDTV and digital broadcasts, what the hell? Just send the goddamn original image and let the player handle it!

Pixels are not always square.

Frames are not always frames. As an example, NTSC TV signals are interlaced and use non-square pixels at 29.97 Hz. The frequency of a movie is 24 Hz, but often 12 Hz with repeated frames. A technique known as 2-3 pulldown is used to create closer to 30 Hz output, with interlacing mixed in.

Some TVs can handle 24 Hz signals (one of the reasons why you want a 120 Hz LCD TV over a 60 Hz one is that 120/24 = 5, while 60/24 = 2.5, and you can't show a frame for 2.5 frames), others cannot. So you need something going on there (3 2 3 2 3 2?)

As noted, NTSC SD signal pixels are non-square. So when displaying a SD signal on an HD display, the raw pixel count isn't sufficient -- you need to know either the pixel aspect ratio or the overall aspect ratio of the signal.
Last edited by Yakk on Fri Mar 22, 2013 1:55 pm UTC, edited 1 time in total.
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Kit.
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Re: 1187: "Aspect Ratio"

Postby Kit. » Fri Mar 22, 2013 7:34 am UTC

Steve the Pocket wrote:With broadcast television, it would be a lot harder to make work, because you're dealing with a continuous stream. Trying to switch resolutions in mid-stream would be like trying to create a video file that changes its own resolution at some point in the middle.

For HD it's not a problem (the resolution information is repeated in the stream every second or two, otherwise you wouldn't be able to start playing it after you tuned on it). For SD... well, first of all, there are no (standard) "widescreen" SD formats.

jgh
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Re: 1187: "Aspect Ratio"

Postby jgh » Fri Mar 22, 2013 2:53 pm UTC

For a long time my cable company transmitted a program called "TARGAT SG1".

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Coyne
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Re: 1187: "Aspect Ratio"

Postby Coyne » Sat Mar 23, 2013 7:59 pm UTC

I was telling my Mom about this comic, and she connected it that insurance commercial where the truck with the steel beams crushes the car between it and another truck. Shen figures Randall is driving the truck in front, so the guy that owned the car must have uploaded one of those broken videos.
In all fairness...

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Sakutarou
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Re: 1187: "Aspect Ratio"

Postby Sakutarou » Thu Mar 28, 2013 3:07 pm UTC

I registered for this forum specifically so I could say that incorrect aspect ratios with pictures and video are something that really, really get under my skin. Though my methodology would be to put them in a box until they realize that scrunching things up that shouldn't be scrunched up that way is bad.

And that they didn't have any Animorphs books at the local library when I was younger.


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