anamorphic Dvd?

[vrpatilisl]

hi
In many thread i read that anamorphic dvd are to be ripped anamorphicaly. Why that so, i was thinking that video in anamorphic stored in square pixel with anamorphic flag only. And why NTSC 4:3 dvd are always anamorphic? What about PAL 4:3 dvd.
Thanxs

[TheSkiller]

Any type of DVD uses non-squre pixels, in other words, DVDs are always anamorphic, 4:3 and 16:9, PAL and NTSC.

The benefit of not resizing (leaving it anamorphic) for backups is it saves bitrate because like that there is no resizer that stretches the image to the correct square pixel proportions making it bigger (more pixels) without actually containing any real additional resolution. If you downsize so that it is in square pixel proportions, then you lose valuable information that was there.
Keeping it anamorphic avoids all that. A flag that you must specify (works with MKV container, MP4 I'm not sure) will tell the player how to de-squeeze the picture during playback.

[hello_hello]

Anamorphic video in an MP4 is fine. Well the container supports it. I can't speak for all hardware.

Can I add.... anamorphic encoding (forgetting cropping for the moment) uses the same resolution as the DVD video and the player stretches the video to it's correct aspect ratio the same way it would for a DVD. So if the DVD resolution is 720x480 (NTSC) the encoded video will be 720x480. It can either have a 16:9 or a 4:3 aspect ratio, but the resolution is the same.
Non-anamorphic encoding means stretching the picture to the correct aspect ratio, then encoding it using square pixels, which as TheSkiller said results the encode using a different number of pixels (having a different resolution) to the original video.

[vrpatilisl]

thanxs 4 reply.
I have seen many dvd cover where anamorphic is not writen. How to find the video is anamorphic using any software.

[Ghitulescu]

thanxs 4 reply.
I have seen many dvd cover where anamorphic is not writen.

Because it's like writing on a plane that it has wings.

However, in common language, anamorphic DVDs are those containing 16:9 video (or 1.84 or 2.25 or 2.40 and so on) within a 720x576/480 frame size. The opposite, in this sense, is Letterbox.

[hello_hello]

thanxs 4 reply.
I have seen many dvd cover where anamorphic is not writen. How to find the video is anamorphic using any software.

They're all anamorphic. They either have a 4:3 aspect ratio or a 16:9 aspect ratio. Movies with wider aspect ratios add black borders top and bottom which most people remove when encoding.
An encoding GUI, whether it can encode anamorphic video or not, should automatically detect the correct aspect ratio when decoding the video.
Because NTSC and PAL DVDs have a different resolution (720x480 vs 720x576) they use different shaped pixels, but once again an encoding program will automatically detect whether a DVD is PAL or NTSC.

Are you using any encoding program in particular at the moment? Keep in mind too that if you're encoding using Xvid/AVI etc. most encoding software won't encode anamorphically because anamorphic AVIs aren't well supported in hardware players. When encoding using Xvid they resize to square pixels instead.
Anamorphic h264 video on the other hand is fairly well supported in an MKV or MP4 container, however it'd pay to test your player (if it's not a PC) to verify it does support anamorphic MKV/MP4. If it doesn't then you might have to stick with square pixels for h264 encoding as well.

[Amateur]

Any type of DVD uses non-squre pixels, in other words, DVDs are always anamorphic, 4:3 and 16:9, PAL and NTSC.

The benefit of not resizing (leaving it anamorphic) for backups is it saves bitrate because like that there is no resizer that stretches the image to the correct square pixel proportions making it bigger (more pixels) without actually containing any real additional resolution. If you downsize so that it is in square pixel proportions, then you lose valuable information that was there.
Keeping it anamorphic avoids all that. A flag that you must specify (works with MKV container, MP4 I'm not sure) will tell the player how to de-squeeze the picture during playback.

How do you anamorph down to 4:3 keeping the original 720x480 aspect ratio? I've never done this and thought it was always better to just resize down to 640x480 if you desire a 4:3 ratio

[hello_hello]

You're probably not understanding the distinction between the storage aspect ratio and the display aspect ratio. SAR × PAR = DAR (PAR being the pixel aspect ratio).
In the case of your DVD example 720x480 is neither 4:3 nor is it 16:9. It's the storage aspect ratio. Therefore the equation tells you each must use different shaped pixels (neither being square). They use a different pixel aspect ratio.

640x480 is commonly used for 4:3, but 704x528 is also 4:3, although you'd probably only do it that way for PAL video and the file size will be larger while the visual difference will be fairly minor.
Once again though, both resolutions are resizing to square pixels, so the storage aspect ratio and the display aspect ratio is one and the same. That's not the case for DVD. 720x480 isn't 4:3, it gets resized on playback to display that way. So for anamorphic encoding you encode it at 720x480 (the idea being you don't loose detail through resizing) and it gets resized on playback to 4:3 just as the original DVD does.

Exactly the same principle applies to 16:9 video, the only difference is the shape of the pixels used to give a 16:9 display aspect ratio. The storage aspect ratio is still 720x480 (NTSC) or 720x576 (PAL).
As you didn't answer the question as to which program you're using for encoding I can't tell you if it's capable of anamorphic encoding or how to do it, but a decent program capable of it will calculate the pixel aspect ratio accordingly so you shouldn't have to think about it too much. To a certain extent you just crop the video in the usual way and then encode it.

[Vurbal]

How do you anamorph down to 4:3 keeping the original 720x480 aspect ratio? I've never done this and thought it was always better to just resize down to 640x480 if you desire a 4:3 ratio
It's important to look at the context of the word anamorphic because it is used in different ways. Technically it just means shape changing, and can be used to refer to any image where the aspect ratio is different than the ratio of horizontal to vertical resolution. Using DVD as an example, and setting aside ITU resizing to keep things simple, 720 divided by 480 is 1.5 or 3:2. Since a 720x480 image is used for either a 4:3 (1.33) or 16:9 (1.78) aspect ratio, the image would be anamorphic either way. In other words, if the PAR (Pixel Aspect Ratio) is either wider or narrower than 1:1 (as it always is for DVDs), you are dealing with an anamorphic image.

This is different from the definition of anamorphic as used in the DVD-Video standard where it includes only video with a 16:9 AR.

[hello_hello]

This is different from the definition of anamorphic as used in the DVD-Video standard where it includes only video with a 16:9 AR.

That's a very good point, and something the rest of us have probably forgotten about while describing all DVDs as anamorphic.

vrpatilisl,
The way I understand it in terms of the way a DVD might be labelled, 4:3 DVDs are generally described as "full screen", whereas DVDs can be described as widescreen, enhanced widescreen or anamorphic widescreen etc if they use the 16:9 aspect ratio.
I think they're labelled that way because it's possible to put a 16:9 aspect ratio video on a 4:3 pixel aspect ratio DVD, but to make it display correctly black bars need to be added to the top and bottom of the picture because the image itself is 4:3. That's the way it was often done in the early days when everyone had 4:3 TVs.
As 16:9 TVs became more popular DVDs using a 16:9 aspect ratio became more common. They're the DVDs which may or may not be labelled widescreen or anamorphic etc. I don't think anyone thinks about it these days as pretty much all widescreen/16:9 DVDs use the 16:9 pixel aspect ratio.

So in terms of whether a DVD is labelled as anamorphic or not, that's the reason for it, but when it comes to using anamorphic as a way to describe DVDs in a forum such as this, they'll usually all be described as anamorphic because none of them use square pixels.

[Ghitulescu]

However, in common language, anamorphic DVDs are those containing 16:9 video (or 1.84 or 2.25 or 2.40 and so on) within a 720x576/480 frame size. The opposite, in this sense, is Letterbox.

That's a very good point, and something the rest of us have probably forgotten about while describing all DVDs as anamorphic.

Speak about yourself, please.

[SeeMoreDigital]

Well done TheSkiller and Vurbal ;)

[hello_hello]

Speak about yourself, please.

I said "probably", but I apologise for not specifically making an exception for your unrivalled brilliance.
Now I've re-read your earlier post I see what it was you were attempting to explain.

[vrpatilisl]

thanxs everybody,
what dvds in pre 16:9 era.At that time only 4:3 tv available. I think first dvd is released in 1997.

@ seemoredigital
Nice guide mate.

[vrpatilisl]

In the case of an NTSC 4:3 (Standard / Fullscreen) DVD Images:
Because we already know the 'height' uses 480 pixels, all we need to do is multiply 480 by 1.3333 and we get a target width-ways pixel quantity of 640. And because you also now know that all NTSC anamorphic DVD's contain just 720 'width-ways' pixels (and not the required 640 pixels) ARS has to be applied to" stretch" the 'width-ways' pixels to an imaginary imaginary target width of 640 pixels.
@ see more digital
I dont understand why to strech cause we already got 720.
Thanxs

[hello_hello]

I think "stretch" is probably the wrong word there. He probably just used it for consistency with the rest of the examples. The 4:3 NTSC example above would have it's width reduced to 640 square pixels. It's the only DVD format which uses a PAR less than 1:1. NTSC 16:9 and both PAL formats use a PAR greater than 1:1, so if you keep the original height, the width does in fact have to be stretched.

[Ghitulescu]

I dont understand why to stretch cause we already got 720.
Anamorph means that the PAR is not 1:1. All DVDs and consumer formats prior to HDTV are anamorph (except maybe the Amiga 640x480 mode, but who uses today Amiga?).
When people talk about pixels and 640 and stuff they always think that PAR is 1:1.
352x576, 352x288, 480x576, 544x576, 704x576 and 720x576 (the most used framesizes in MPEG-1/2 PAL videos) may be all of them 4:3, or a DAR of 1.33333333333333333, irrespective whether eg 352 : 576 = 0.61111111111. Or maybe 16:9. One can never guess the format of a video just looking at its framesize.

To understand, have a further reading in Aspect ratio threads and stickies, maybe in wikipedia as well (it's free).

[vrpatilisl]

from above discusion my conclusion is
that dvds(PAL,NTSC) Both store video anamorphicaly and strech (16:9) or compress(4:3) accoring to dispay. Is my conclusion right?
Thanxs

[hello_hello]

Not really, Not if "according to the display" refers to the TV itself. If you want to think of it in terms of square pixel equivalents and while keeping the original height, all formats are stretched horizontally to the correct aspect ratio except NTSC 4:3 which is reduced. I definitely wouldn't say they're stretched or compressed according to the display as such, because they should be stretched or compressed to their correct aspect ratio regardless of the display. A 16:9 DVD should display as 16:9 on a 4:3 display, only it'll have black bars top and bottom. Likewise a 4:3 DVD will still display as 4:3 on a 16:9 display, only it'll have black bars down each side.

Something else to ponder....
A 4:3 display, for example (and for the purposes of this discussion) has a horizontal resolution of 720 pixels. A 16:9 DVD has a horizontal resolution of 720 pixels. So how do you make a 16:9 image display correctly on a 4:3 display? If you can't stretch it out horizontally because 720 pixels is the limit for standard definition, then you've got to reduce it vertically.
Which is exactly the same way most people convert DVDs to square pixel AVIs. Instead of stretching the width to get the correct aspect ratio (1024x576 in the case of PAL) you'd reduce the height. Which is why you'll find most standard definition widescreen AVIs have a resolution of 720x400 or 720x368 etc. etc.

So forget the "according to the display" part. The only way a 16:9 DVD can be displayed correctly is with an aspect ratio of 16:9, whether you stretch the width, reduce the height, upscale it to high definition or resize it down to play on an ipod. Likewise the only way to correctly display a 4:3 DVD is with a 4:3 aspect ratio. If the aspect ratio of the display doesn't match the aspect ratio of the DVD, then generally black bars are added somewhere to allow it to display correctly.

[SeeMoreDigital]

from above discusion my conclusion is
that dvds(PAL,NTSC) Both store video anamorphicaly and strech (16:9) or compress(4:3) accoring to dispay. Is my conclusion right?
ThanxsYes... that's close enough ;)

[Amateur]

so If I wanted to anamorph a DVD display to 4:3 from a 720x480 resolution, what would I add to my script? I have always just let MeGui do it's clever anamorphic feature to automatically get 16:9 but I'm not sure if that option is selectable for a 4:3 picture

[SeeMoreDigital]

so If I wanted to anamorph a DVD display to 4:3 from a 720x480 resolution, what would I add to my script? I have always just let MeGui do it's clever anamorphic feature to automatically get 16:9 but I'm not sure if that option is selectable for a 4:3 pictureFor ultimate accuracy you need to refer to the DVD source... Take a still image from the DVD source!

Sufficed to say, this is where matters can get complicated. As hello_hello has already eluded to there are many, say 2.35:1 "letterbox" anamorphic movies available (on mostly NTSC flipper DVD's) encoded at both 4:3 and/or 16:9.

Indeed for many years, big blockbuster 2.35:1 movies such as Titanic and The English Patient were only available in "letterbox" 4:3 DVD. Obviously they looked awful because around 34% of the vertical resolution was not available... compared to their (now available) 16:9 DVD versions.

[hello_hello]

so If I wanted to anamorph a DVD display to 4:3 from a 720x480 resolution, what would I add to my script?

Nothing, just let MeGUI do it. It'll automatically detect if the disc is 16:9 or 4:3. It rarely gets it wrong and if it did you'd know about it because the encode would look seriously stretched or squashed.

I have always just let MeGui do it's clever anamorphic feature to automatically get 16:9 but I'm not sure if that option is selectable for a 4:3 picture

It is. Maybe you've just never encoded a 4:3 DVD?
I don't know how much information MeGUI gives you if you use the "one click encoder" as I've never used it, but doing it the other way where you index a file and then MeGUI opens the AVS script creator for you to set up your encode, there's a drop down box labelled "input DAR" in the AVS script creator window. Whatever is listed there when the AVS script creator window opens is the type of disc MeGUI has detected and as I said, it's virtually always correct.
If you're converting a 4:3 NTSC DVD it'll be listed in the drop down box as "ITU NTSC 4:3 (1.367377)". If it's a 16:9 NTSC disc it'll be listed as "ITU NTSC 16:9 (1.823169)". There's also non-ITU resizing options in the drop down list, 4:3 (1.333333) and 16:9 (1.777777). MeGUI defaults to using the "official" ITU resizing method. Which one you use is a whole other subject, but the difference isn't all that great anyway.

The above applies whether you're using "clever anamorphic encoding" or not. Even if you're not and resizing to square pixels, MeGUI still has to detect whether the disc is 16:9 or 4:3 in order to resize it correctly.

[vrpatilisl]

@ see more digital
"thas close enough" means what i missing please tell.
Thanxs

[Ghitulescu]

@ see more digital
"thas close enough" means what i missing please tell.
Thanxs

Have yourself a search after DAR and you'll find out :)

[vrpatilisl]

hi
Now my understanding changed now my conclusion is, previously dvds like titanic and The english patient (thanxs @seemoredigital) are in 4:3 with display adding black bar in top and bottom to prevent loss of picture frame, later full screen dvds came which show picture in 4:3 fully without bars. And now 16:9 dvds with full picture frame "without" adding blackbar on 16:9 display.
Is this right?

[Ghitulescu]

hi
Now my understanding changed now my conclusion is, previously dvds like titanic and The english patient (thanxs @seemoredigital) are in 4:3 with display adding black bar in top and bottom to prevent loss of picture frame, later full screen dvds came which show picture in 4:3 fully without bars. And now 16:9 dvds with full picture frame "without" adding blackbar on 16:9 display.
Is this right?

Not really, it depends.
http://forum.doom9.org/showthread.php?p=1494312#post1494312

[Amateur]

I've done lots of 4:3 DVD encodes but I have always simply resized them to 640x480. I didn't know I could put in a display call to make the 720x480 appear in 4:3 which is what I'm wondering how to do. The only time I did clever anamorph in MeGUI was for a 16:9 (1.78:1) aspect ratio (usually TV shows that are aired in widescreen).