I understand that anamorphic involves non-square pixels, and that with the information about the PAR/SAR, the modern TV and player can use this information to make the video image pop out to fill the screen as needed for either 4/3 or 16/9 content. It's not like the old days where when you had widescreen / letterbox / NTSC and you had to manually adjust the screen size if you wanted to eliminate the pillarbox effect.
But as far as the absolute quality of playback, I've always been a bit confused as to what extra, if anything, anamorphic encoding gives you.
Scenario: You have exactly the same source data, same number of gigabytes, same bitrate, etc., etc. On the one hand you encode that data anamorphically, and on the other hand you do not, relying instead on the old method of manually adjusting the pillarbox appearance to fit the 16/9 screen correctly.
Would you have any reason to expect a better quality of playback just because in one case the data was encoded anamorphically?
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Anamorphic has NOTHING to do with 4:3 video. If you want to stretch that 4:3 frame to fit a 16:9 screen and distort the image then go ahead.
The point of anamorphic is that the 16:9 video is squashed in to a 720*480(for NTSC) SAR which is then corrected at playback. The only other way to get 16:9 would be letterboxed in a 4:3 frame. You would have to zoom that image to fill your 16:9 screen and reduce quality in to the bargain. So anamorphic for no other reason gives you better quality.
"Popping out" of the image to fit the screen, is only available when the player app supports it and is set to "fit screen". For example, SD material that goes to my TV is 4:3 720x480 (from, say, a DVD player that doesn't upscale). My 16:9 HDTV is set to "Keep original DAR of Source", so it fills to a 4:3 section in the middle of my screen and leaves pillarboxing on the sides.
All other things being equal, there is no quality improvement by using anamorphic. But all things are rarely if ever equal. Anamorphic usually allows you to maximize your given proscribed frame. This in itself gives better quality.
Your scenario assumes you are encoding 4:3 material as 1:1 PAR instead of the usual non-square PAR (NTSC being 8/9 or 10/11 depending on how you count). I say USUAL, because it is. It is only PC-originated material, lower-grade consumer stuff or re-compressed copies that are SD and are 1:1PAR. Anything that originated on Analog tape and was converted to Digital, if it was done according to official 601 standards, would be non-square.
So, if you have no constraints on frame size, such as when originating something on a PC that will be played on that PC, you can make your frame whatever is optimal for your desired image AR. That isn't possible in the Analog or CE world: your TV can't shapeshift.
What is the intent behind your question? Are you trying to avoid anamorphic encoding? Or justify creating everything as square-pixelled. Those decisions are best based on your devices' capabilities and your prepping & viewing habits & preferences.
BTW, I could give you a better example of what I just explained if you gave me an actual concrete scenario instead of a hypothetical.
BTW, Anamorphic is NOT exclusive to SD or 4:3. HDV material is anamorphic - 1440x1080 in a 16:9 DAR using 4:3 (not usual 1:1) PAR. And 2.35:1 film material is often shot anamorphically.
720x480 with widescreen flag was invented to effectively store 16:9 footage into 720x480 resolution that was available.
Last edited by _Al_; 22nd Apr 2014 at 17:35.
Black bars all around should be 16:9 letter-boxed in 4:3 and properly displayed in 4:3. So the pillar bars are provided by the 16:9 display.
I have been watching a dvd series (Inspector Montalbano) which is just that.
Of course a tv could provide a way to zoom in and remove all the bars to fill the screen. There would be no distortion since the underlying image is 16:9.
Maybe I mis-interpretated what you were trying to say about 4:3 since if it is pure 4:3 there is no way that should fill the 16:9 screen without distortion. I will add one caveat to that since hdmi up-scaling could do some tricks to 4:3 video on a 16:9 tv. Maybe my eyes have deceived me but when I watch some 4:3 video ion this way it does look quite normal.
There are not, and could not be, any more pixels.It is just how they have been encoded. The ultimate issue for quality is bitrate and the source. Anamorphic does not add anything to that.
BTW discussion about film only clouds the issue to a degree. But the principal is the same. The width to height ratio is fixed (unless you use dedicated cameras and film stock). So the camera shoots with 3:2 (standard) film but with a lens to 'squash' the image. The projector must then have a lens to reverse that 'squash' otherwise all actors suddenly got thinner
You shouldn't need to confuse DTV anamorphic encoding with Anamorphic film: they are the same thing. One does it digitally (usually) and one does it optically, but they can be interchanged on some level. Film Ana. refers to the process, not necessarily the device/lens (although the device is what enables the process). Note that you can still get ana lenses for DTV, DSLR video, even your iPhone!
Think of ALL video as having DAR, PAR and SAR (I prefer to just say stored resolution). Then, think that the square pixel PAR is just a SPECIAL CASE of the generalized occurrence of non-square images. And DAR = PAR * SAR. Solid rule.
The movie industry used the term anamorphic to distinguish 16:9 DVDs from 4:3 DVDs, but if you use the term anamorphic to describe any video which has non-square pixels then all DVDs are anamorphic. They all have the same 720x480 resolution, but in the case of 16:9 they're stretched to 16:9 on playback while for the latter it's 4:3.
You can put a 16:9 image on both a 16:9 and 4:3 DVD. For the former the entire 720x480 worth of pixels are used for the video, for the latter there'd be black bars top and bottom. Likewise you can put a wider than 16:9 aspect ratio on a 16:9 DVD which would also require black bars.
The reason a widescreen image on a 4:3 DVD looks "letterboxed all round" when displayed on a 16:9 screen is because the total aspect ratio is 4:3. It's already got black bars top and bottom so the sides need to also be filled with black (the player adds them on playback) to make a total aspect ratio of 16:9.
Without trying to be to scale.....
Image 1 is a 4:3 image being displayed on a 16:9 screen. The player is adding the black bars down the sides in order to fill the screen.
Image 2 is a 4:3 image with a widescreen picture. The picture is encoded with black bars top and bottom (grey in the pic). The player still adds the black bars down the sides to fill the screen.
For a 16:9 DVD the image is stretched to fill the screen, so the same widescreen image would be encoded using more of the 720x480 worth of pixels when put on a 16:9 DVD.
I think by making the image "pop out" you might be referring to "zooming in" until the end result is pic 2 displays the same as pic 3. If you zoomed in on the 4:3 image until the "side" black bars were gone the widescreen picture would look the same as it does when it's on a 16:9 DVD without zooming, but it'd have a slightly lower resolution.
Putting widescreen images on a 4:3 frame happened a bit back in the early days when we all had 4:3 TVs, but it's not done much any more.
Anamorphic is generally a way if trying to fit more display aspect ratio into a lower resolution. Itunes use a 960x720 resolution for some of their 16:9 content but even though the resolution is only 960x720, it displays as 1280x720 (16:9). Obviously the resolution is lower than if it consisted of 1280x720 worth of square pixels, even though it displays the same way.
Last edited by hello_hello; 22nd Apr 2014 at 22:08.
Let me have a crack at this. If you imagine an accordian compressed, that's what an anamorphic sequence is. Then when you pull the accordian open, that's what the picture ends up as.
More Detail: The DVD player is the "Un-Anamorphicator"
By the way, both 4:3 and 16:9 DAR are technically anamorphic in 720x480 frames. 16:9 is squished horizontally, 4:3 is stretched horizontally. Neither is square pixel.
hello_hello: "Image 2 is a 4:3 image with a widescreen picture. The picture is encoded with black bars top and bottom (grey in the pic). The player still adds the black bars down the sides to fill the screen."
So in this case, some of the actual pixels are being used to encode hard matted black bars top and bottom. The anamorphic uses no pixels for this process, and therefore has more pixels for image quality ...
hello_hello: "If you zoomed in on the 4:3 image until the "side" black bars were gone the widescreen picture would look the same as it does when it's on a 16:9 DVD without zooming, but it'd have a slightly lower resolution."
jagabo: "Yes. A 16:9 DAR source letterboxed in a 720x480 4:3 DAR frame occupies only about 720x360 of the frame. An anamorphic version fills the full 720x480 frame."
And thanks again. The result is that there's nothing that bitrate can do to overcome this disadvantage.
Yes, as I said before, Anamorphic allows one to more fully utilize the constraints of the frame, by squeezing the image non-linearly.
Because of the aspect of media where a downsizing retains the perceptual sharpness of its parent, while an upsizing retains the perceptual fuzziness of its parent, it makes much more sense to start with a greater-than-full rez image and squeeze it into a full rez frame and then upon playback resize down again to the equivalent original AR but fitting within that frame using post-generated letter/pillar-boxing, rather than start with the greater-than-full rez image, resize down to a letter/pillar-boxed image that is then encoded & stored that way and then decoded and played back as-is. In the former, much of the compressed encoding artifacts will be minimized by the subsequent re-downsizing. Not so in the latter example.
There is a similar process that used to go on in analog audio with pre-emphasis & de-emphasis (EQ), or with compansion.
My pics assumed the widescreen image was slightly wider than 16:9 (2.35:1 for example) which is why pic 3 still has black bars top and bottom, but the principle is still the same. A 16:9 image on a 4:3 frame would have black bars top and bottom, whereas the same picture on a 16:9 frame would not, but if the picture is wider than 16:9 they'd both have black bars, however the 4:3 frame would require more of them so the resolution is still lower.
I always crop the black bars when encoding so there's no need to end up with a situation as in pic 2. Even for pic 3, where the picture might, for example, only use 720x364 of the resolution (a total of 116 pixels of black bars top and bottom) most people remove them when encoding as the player would add them back on playback anyway. If you encode anamorphically you'd encode at 720x364 (black bars removed), the picture should still be stretched to the correct aspect ratio on playback, then the black bars are added and you're back where you started. I say "should still be stretched"......
Me.... I don't use anamorphic encoding as a couple of the players in this house don't obey aspect ratios in MKV/MP4 files and display the video as though it has square pixels. So I'd resize a 16:9 NTSC DVD to something like 854x480 and encode it that way. If the picture has a wider aspect ratio than 16:9 you might end up (as per my previous example) resizing to something like 854x364 after removing the black bars. The display aspect ratio would still be the same and the player would still add the black bars back on playback.
If that same 2.35:1 video was encoded onto a 4:3 frame, after cropping the black bars and resizing to square pixel dimensions you'd end up with something like 640x272 if you reduced the width, or 720x306 if you stretched the height, but either way it'll have less resolution than the version on a 16:9 frame.
You don't gain anything in terms of extra resolution by resizing to square pixels when encoding. In fact it increases the file sizes because there's more picture to encode (depending on the resolution you resize to), but it doesn't add any picture detail back. It just eliminates any anamorphic playback issues. If the encoded version has square pixels, it should always display correctly.
Last edited by hello_hello; 23rd Apr 2014 at 02:56.
The reason we have anamorphic encoding of 16:9 DAR DVD is that they didn't want to add extra cost and complexity in the early days of DVD. To have square pixel encoding of NTSC DVD would require a ~854x480 frame (1024x576 for PAL). That would require more memory, more memory bandwidth, stronger decoding chips, and and more bitrate to keep from breaking up into blocky artifacts. It's much easier to stretch the output horizontally with the graphics chip.