aspect ratios

Since I'll be needing a new video projector soon, I've been toying with the idea of swapping out my 4:3 projection screen for a wider one, and the whole aspect ratio thing has me completely puzzled.

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I have no HDTV gear, and don't feel any need for it (since there's basically no HDTV content available that I care about). However, it would be nice, when watching letterboxed movies, to have them grow horizontally rather than shrinking vertically. In other words, it'd be nicer to have vertical black bars with TV than horizontal black bars with movies.

So basically, I'm trying to figure out whether this is worth the effort, and how much of a pain in the butt it will be (both up front, and on a day-to-day basis.)

(Really I'd rather have a 116" diagonal LCD instead of a projector, but they don't exist.)

  1. As far as I know, most movies are 1.85:1. But the whole home theatre and HDTV world seems to have standardized on 16:9 (AKA 1.77:1) which is a lot less wide. This means that letterboxed movies won't fill the whole screen, and even after upgrading your gear, you still have black bars at the top and bottom.

    This is madness, is it not?

  2. I guess I have three choices for how to project onto a 16:9 screen:

    1. Get a 16:9 projector (they exist, but are rare);
    2. Get a 4:3 projector, and an "anamorphic" adapter lens that stretches the 4:3 image to 16:9;
    3. Get a 4:3 projector, and project an image that is as wide as the screen (but 30% taller.)

    Options 2 and 3 sound pretty kludgey, but option 1 severely limits the choice of projectors. What is the Done Thing?

  3. Pretty much the only two video sources I use are DirecTivo (non-HDTV version), and Playstation 2 (for playing games and watching DVDs).

    In a setup like that, how much of a pain in the butt is it to switch modes? Is this something that you do with the source signal, or with a setting on the projector, or both?

    I see that my Tivo has a preference for TV aspect ratio that lets you choose "4:3" or "16:9", but when I change that, nothing seems to happen. I expected it to stretch the image or something, but I can't see any difference at all.

So can someone with experience with this stuff tell me how it actually works in practice?

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65 Responses:

  1. c0nsumer says:

    Regarding Section B:

    IIRC, #2 is exactly how 35mm film is projected in theaters. That's the idea behind anamorphic... A full frame is shot, and anamorphic lenses are used to provide the correct aspect ratio. The problem I see with this is that if you then want to watch 4:3 content, you'd either need to switch out lenses or have an input which would shrink the content automatically.

    I personally think the idea solution is to go with #1 would be the best idea, as it would do precisely what you want, and without any sort of hacks. I remember 16:9 projectors being rather pricey, but if you can find a reasonable one, I'd go with that.

    • nmg says:

      #2 is how Cinemascope film (2.35:1) is projected in cinemas; an anamorphic lens is used to stretch an Academy aperture frame (1.37:1) to full screen.

      That said, there are many 35mm films which are not projected using anamorphics. The standard aspect ratio for European film is 1.66:1 (that for US films is 1.85:1), both of which use a reduced area of the 35mm frame.

  2. edm says:

    Movies range between about 1.66:1 to 2.33:1 (ignoring the old 1.33:1 movies), depending on the process used. From what I remember of my DVD collection 1.85:1 and 2.33:1 are about equally represented.

    I believe the 16:9 ratio (1.77:1) was chosen for widescreen TV because it was reasonably close to both 1.33:1 (4:3, ie "fullscreen"), and 1.85:1 (common widescreen movies) without leaving excessively large parts of the screen unused in either case. But you still get sigificant parts of the screen unused in the 2.33:1 situations; that's kind of a "no win" situation, as if the screen were 2.33:1 then 1.33:1 ("fullscreen") would like pretty horrible on it.

    I'm not really sure what the right answer would be with a projector. I believe the movie theatres actually use anamorphic lenses (and other appropriate lenses), but that seems far too much like hard work for "home theatre". If I were doing it I suspect I'd get a 1.33:1 projector (since they're readily obtainable), and a screen something like 16:9, and set it up to project slightly larger (vertically) than the screen and live with the compromise. YMMV.


    • fo0bar says:

      ... except when you're watching 4:3, you have to shrink it down in software, leaving you projecting black bars on the top, bottom, left and right sides. Uhhuh.

      If your 4:3 viewing habits include more than a tiny minority, I'd just recommend getting a larger 4:3 screen and living with bars on the top and bottom during widescreen viewings.

      • edm says:

        Actually what I had in mind was letting the 4:3 bleed over the top/bottom of the screen a little (onto whatever is behind it), and living with that. Friends of mine with 16:9 TVs seem to mostly leave it set in a mode that makes 4:3 full width, and chops off the top/bottom, and it's still pretty watchable.

        As I said, YMMV.


        PS: Assuming the projector or screen can be moved, "shrinking it down" can be achieved in hardware simply by moving the projector and screen closer to each other.

        • relaxing says:

          My HDTV (a Panasonic) has a "Just" mode which stretches the 4:3 image less in the middle and more on the outer edges, under the mostly correct assumption that the important stuff is happening on the center of the screen. I find this more watchable than chop mode (which makes the SD signal even more blurry.)

  3. brad says:

    Movies range all over in size. The HDTV ratio of 16/9 (1.778) was chosen because it was about halfway between TV (4:3) and movies (often 2.35:1).

    Another common aspect ratio, often used in comedies, is 1.85:1. They shoot in that because comedies are sold often in VHS/DVD, and it makes the pan & scan process (cropping the sides off and focusing on the "main" area) easier, without pissing people off who don't understand black bars.

    So widescreen isn't too painful... half the movies fill your whole TV, and half only have minor black bars on top/bottom.

  4. edolnx says:

    My friends and I all have 4:3 projectors. We looked into 16:9, but decided that full screen video games, computer, and to a lesser extent DirecTV were going to loose out on 16:9 gear. We had the advantage of playing with a 4:3 for a while (first person who bought one) and finding a very cool local home theater store that encourages you to test equipment and content on the equipment you are planning on purchasing in store. In the end, we agree that 4:3 is the right choice. Our screens are all 6'x8' and up - so the movies are huge anyway. GT4 at that size is quite amazing as well.

    As for all content being 1.85:1 - you'll note that a lot of new movies (and theaters) are 16:9. This is because the HD movie standard is 16:9 - so most stuff shot digitally is now 16:9. For example, I know Sin City was 16:9, and I believe that Star Wars 1, 2, and 3 are as well.

  5. violentbloom says: I thought that directTV was sending stuff as mpeg4 but I could be wrong. That would imply that it's using some ratio based on the cif standard 704x576. But that's probably not relevant.

    • mark242 says:

      DirecTV sends MPEG-2 in the video stream, and either MPEG-1 or AC3 for the audio (depending on if you're on a channel with surround sound).

    • otterley says:

      DirecTV will be transitioning to MPEG-4 through 2007 as it brings its new satellites online so it can supply an HD package equivalent to the SD packages it offers today (1500 locals, 150+ nationals). If you were planning to buy an DirecTV HD tuner (TiVo or otherwise), right now wouldn't be a good time; you would be flushing your $$ down the toilet.

      • violentbloom says:

        Eh, so no wonder I was confused as to mpeg versions. I do phone crap at work which is loosely related to those standards.
        I don't really worry about it much as I don't figure my (non-HD)tv will break anytime in the next few years.

  6. tfofurn says:

    You have already mentioned that you think an anamorphic lens is a kludgey solution. I concur. You're going to end up with individual pixels having a wide aspect ratio. I'd want to see a demo of this technique before buying it. I suspect that movie theaters get away with it because 35mm has so much detail.

    <wank>I'm thinking back to the brief time I spent working with video capture . . . an anamorphic signal looks no different to an analog display, as there's still the same amount of time between horizontal retraces. The rate at which the signal changes, though, is higher. Thus, an anamorphic signal would be resampled on-the-fly on a 4:3 set. </wank>

    • bassfingers says:

      You're going to end up with individual pixels having a wide aspect ratio.

      Well, that's already the case with just about ANY dvd out there, isn't it? IIRC the DVD standard doesn't use square pixels...

      • tfofurn says:

        I'll presume you know all this, and I'm just explaining myself at this point. The projector has a fixed number of pixels across the screen, regardless of their shape. Sending more pixels across to the projector will not magically increase the number of pixels displayed, even if those pixels are then stretched horizontally by a lens. I suspect that pixels made unnaturally wider by the lens will not look right.

  7. usufructer says:

    One of the Done Things is to use more than one normal 4:3 projector. Expensive, and you have to have the projectors aligned well.

    Your option 3 has the side benefit of cropping off the annoying scrolling tickers often seen on news channels. That beats the duck tape method.

  8. lars_larsen says:

    Anamorphic lenses ONLY stretch the image horizontally. So if you show a 4:3 movie through a 16:9 anamorphic lens, you'll see a bunch of wide stretched out people looking silly. If you watch a 16:9 movie on a 4:3 projector with such a lens, you'll see wide stretched out people with wide stretched out black bars at the top and bottom.

    What you'd need to do is "squish" the image horizontally but not vertically in software. Then let the lens "unsquish" it. I dont believe 4:3 projectors do that automagic squishification do they?

    • jonabbey says:

      You'd need a DVD player with an option to let you play anamorphic video without doing any processing at all when viewing, leaving that for the anamorphic lens to handle. Anamorphic DVD's are full-height in the encoding, the black bars are inserted at top and bottom on play-back.

      I do not know whether such beasts exist.

      • wfaulk says:

        They do exist. I'd be surprised if there were any that didn't do that. Bascially, you tell your DVD player in setup mode that you have a 16:9 TV despite the fact that you don't. My 4:3 TV automatically switches to its anamorphic mode, but if it didn't have such a mode (as most TVs don't), then you'd get skinny pictures.

  9. chanson says:

    I don't know what the Done Thing is, but I'd just get a 16:9 projector. There are even native 1080p projectors available now, though they're pricey (like this Fujitsu LPF-D711). And at least I'd rather have too many pixels for most of what I watch and have it scaled up than have too few for the really good stuff and have it scaled down.

  10. harvie says:

    The 'aspect ratio' switch in the TIVO should:

    When set to 4:3 and the device is outputting full-frame 16:9 content (where the 'square' frame contains data that is squished horizontally): add black bars top and bottom & resize/resample downwards the full frame 16:9 content so the vertical resolution is lessened but the horizontal resolution is unchanged.

    When set to 16:9 and outputting full-frame 16:9: output the full-frame as-is (i.e. if you view it on a dumb terminal you get thin people) and also encode the 'this is 16:9' signal in the video subcarrier or wherever this goes. A smart display unit will then change aspect ratios automatically.

    What you want really is to avoid at all costs losing pixels. If you get good optics, #2 will give you the best quality as it avoids all resampling but you'll have to switch the lens out when viewing 4:3 content.
    #3 is basically how most people use their widescreen TVs as they never seem to bother to set them back to 4:3 for 4:3 content, they just let the set chop off the top and bottom, which is really irritating.
    #1 would be best if the projector has extended resolution in the horizontal, so when displaying 4:3 content it won't be crippled (i.e. make sure the projector has square pixels.)

    Also, as has been said a lot of films are 2.35:1 (Cinemascope, Panavision, etc) so you'll still get black bars top and bottom for those that are. It's not quite so annoying there because the data was never recorded onto the DVD in the first place, so it's not like you're missing anything.

    I would buy a standard 4:3 projector with optical zoom, if such a beast exists. That way when 16:9 content comes on, you zoom in the appropriate direction - this assumes your projection screen is 16:9 and you have the projector zoomed to display 4:3 content with bars either side.

    • jwz says:

      The 'aspect ratio' switch in the TIVO should:

      Is there any reason I should believe it's doing anything at all, given that I've seen no change in the output with either my current projector, or a plain old TV?

      I also seriously doubt that the Tivo has any notion of what the source aspect ratio of the shows it has recorded are (since it's not plausible that random stations will be sending that for non-HD content.)

      • harvie says:

        I don't know whether your broadcaster is embedding the 16:9 signal and sending 16:9 content, as I have no knowledge of the USA market (UK here.)

        I make a vague guess based on the way things are here: if you have digital cable or digital satellite then you should be able to make it work as the 16:9 signal will be generated by the cable/sat decoder based on the flags in the mpeg transport stream. Make sure your cable/sat decoder (if separate from your TIVO) has the '16:9 display' option enabled, or it will be letterboxing the signal for you, instead of passing it on as-is with the 16:9 signal turned on. If your cable/sat decoder is part of your TIVO and 16:9 is enabled there (as you say it is) then 16:9 content should come through on a non-enabled device as full-frame-squished-horizontally. If you're not seeing that then the 16:9 content is probably being transmitted with the bars as part of the input video signal (i.e. badly, but that's the way a lot of places seem to do it because their video engineers don't know shit about shit and/or it's cheaper to produce just-one-stream than to produce two streams, one for 16:9 enabled networks and one for non-enabled.)

      • joe714 says:

        In theory, DTV supports anamorphic content, which displays properly with that setting. Every DTV reciever I've had for the last 6 years has had that setting somewhere.

        In practice, I think they used it a few times for a couple things on Bravo a year or so ago, but that's it. They have the capability to broadcast anamorphic, but they don't.

      • sjn says:

        I am not sure about direcTivo, but I have the TiVo DVDrecorder/DVR combo, and the 16:9 functions only work when I am going to component out. Most (Read all) TV shows do not seem to follow this, wide screen or not. However, if I put a 16:9 enhanced DVD into it, It does switch over to anamorphic scaling, and I have to change my TV's display settings to deal with it.

        You mention using the PS2 as your dvd player, I know for about $30 you can get compnent out for the PS2, what I do not know, is if the PS2 recognizes DVD's that are "widescreen enhanced".

        FWIW: The last projector my dad had (some sony) would switch between 16:9 and Regular TV depending on it's input source. It dealt with this by creating black bars on the left and right for regular 4:3 viewing.

        • jwz says:

          Hmm. Well, my DirecTivo (Philips 7000/17) has composite and S/Video outputs, but not component. So I'm going S/Video from DTV to my tuner (Denon AVR-2805) which then generates component out to go to the projector (it's a long run, and until recently, I thought you couldn't even go that far with S/Video).

          I have both the S/Video and component cables for the PS2, but at the moment I'm using the S/Video cable, because it turns out that while my tuner can upsample S/Video inputs to component outputs, it won't downsample component outputs to composite, which means that my plain old backup tv doesn't get signal. (I use the backup TV for daytime viewing, because my projector is useless until the sun has gone down, even with the curtains closed).

          • sjn says:

            I would then just buy a projector that you like and is nice and bright, and accept the black bars.
            I recently made the mistake of starting to upgrade my tv stuff, and so far it seems to be a never ending money pit, and I am not that picky. I just seem to keep on having to buy "oh, one more thing"

            slightly off topic, but why in the hell does Monster want to charge me $125 for a stupid DVI cable? I get them free with a $300 LCD monitor, does that mean the monitor is only $175? Even the discount brand cable was $80.

      • wfaulk says:

        I was just getting ready to submit a big-old explanation of how the HD TiVos work, but I reread your post and you claim not to have one. I expect that you just have a new remote that has the Aspect button on it. Does pressing that button do anything at all, like pop up something that tells you 4:3 or 16:9 (or however it's labelled)? I bet that it's a NOOP on non-HD TiVos.

        For the record, even on the HD TiVos, the button is unnecessary to irritating. It just sets an option on the TiVo about the shape of your TV, and should be hidden five levels deep in a configuration menu somewhere, not on the remote. (Unless they really think that people are swapping their TVs out constantly.) Basically, it changes if you get bars on the top and bottom during wide material or if you get bars on the sides during narrow material. It's been so long since I set it up that I can't quite remember where it does this, but I do seem to remember that it does absolutely nothing when displaying NTSC material.

        • jwz says:

          There's no such button on the remote; I was talking about the option buried down in the preferences menu.

          • wfaulk says:

            I forgot that it's the Window/PiP button on the HDTiVos that does that and it's not labelled as aspect ratio.

            Now that I'm in front of my HDTiVo, let's see what that does. BTW, the remote button and the buried option are not tied together.

            Hmm. Okay, I have a 4:3 TV, but it does HDTV and Anamorphic 16:9 mode. With the Aspect Ratio setting and the Panel/Full Aspect Correction button (the one I was talking about on the remote) interact like this:

            • In 480i Output Mode
            • Aspect Ratio 4:3
            • When viewing 4:3 recordings
            • Full: Full Screen
            • Panel: Full Screen
          • When viewing 16:9 recordings
            • Full: Squished, Full Screen
            • Panel: Bars at top and bottom
          • Aspect Ratio 16:9
            • When viewing 4:3 recordings
            • Full: Full Screen
            • Panel: Squished, Bars on the side
          • When viewing 16:9 recordings
            • Full: Squished, Full Screen
            • Panel: Squished, Full Screen
          • In 1080i Output mode
            • Aspect Ratio 4:3
            • When viewing 4:3 recordings
            • Full: Stretched, Full Screen
            • Panel: Bars on the sides
          • When viewing 16:9 recordings
            • Full: Full Screen
            • Panel: Full Screen
          • Aspect Ratio 16:9
            • When viewing 4:3 recordings
            • Full: Expanded, Full Screen
            • Panel: Bars on the sides
          • When viewing 16:9 recordings
            • Full: Full Screen
            • Panel: Full Screen

            So, since you only have 480i output and only have 4:3 recordings, the Aspect Ratio option should do nothing except when in 16:9 Aspect Ratio and the Aspect Correction is in Panel mode. Of course, I have no idea if you even have the Aspect Correction option, which is on my HDTiVo, as I said, the Window/PiP button on the remote and also the option immediately above the Aspect Ratio option in the menus.