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Old 22nd November 2011, 07:40   #1  |  Link
Gainnothing
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Questions: Understanding Resizing

This may be one of Doom’s longest questions. It is comprised of like 4 questions or more. This post can also be a learning experience as well as a question to help me with.

INTRODUCTION/PREFACE

Hi people of doom (not Dune). I like to encode videos sometimes as a hobbyist but I was never really a “once-click solution type of guy” . I like to use 4 or 5 programs sometimes just to encode one video. My programs I have used but really do not use them “correctly” may include Avisynth , vdub, quenc, procoder express, BBMpeg, and dgavcdec/dgindex.


I have been doing this for about a few years in my off time. But now I want to even take it a step further by understanding some concepts I really have never taken into account. And when you do not take these things into account, it might as well have been a “Nero click to burn my DVD type of solution”


Basically, I am going to ask some questions regarding resizing and appropriate telecine procedures. But the first question does need some background as to why and how. So it includes my procedure on how I came up to a possible solution.


But even before I begin my questions about this, I will show you some quick examples of incorrect resizing that I have been doing for the last few years or so.

Here is an example: Burn an SVCD

BicubicResize(480,480)

Burn a DVD
LanzcosResize(720,480)

Results: Lazy video where things are CHOPPED OFF. Incorrect usage. My avisynth understanding is not a true understanding. It is a HACK at what is common so that I can learn other things. But now it is time to tighter grasps on the concept of resizing and speed and speed correction. And to tell you the truth, I even found that doing the bottom script is even somewhat of a hack.

I read somewhere that even this is a hack:

LanzcosResize(704,480)
AddBorders(8,0,8,0)

Why is this a hack? Well, even with this so-called perfect solution it still can loose a little of the image. Now the strange thing is I am learning about resizing doing things the uncommon way since most of the time the DVD resizing theory from above was never explained to me in great detail. I do not know even how you guys got 720 x 480 to be resized as (704, 480). But now I am going to things the uncommon way.

Yes, aspect ratio was explained to me and got lost in the wilderness, so I am going to just stick to simple encoding. And when I read the article “A Quick Guide to Digital Video Resolutions and Aspect Ratio Conversions” I found a procedure that works OK for me. But it’s not really well known.. So I am advancing without even knowing the common way of doing resizing. And I will show you how through following this guide I came up with:

Uncommon:
LanczosResize (704 x 476)
AddBorders (8,2,8,2)

Versus:

Common:
LanzcosResize(704,480)
AddBorders(8,0,8,0)

But what is the question? Well my question is: What is the ACTIVE PICTURE AREA in a 640 x 360 matrix since this sampling matrix is not included in the NTSC chart in the article?

I have come up with: 646 5/22 x 368

The second part of the question is: If I use this as the active image area and thus use the LanczosResize (704 x 476) AddBorders (8,2,8,2) script, is it appropriate? Did I kill my image? Did I add to much black stuff to it?

One bit of info I forgot that you probably figured out: The resizing are to DVD 720 x 480 but I think you people at doom probably figured that one out already.

Now: Don’t answer the question yet. Let me show you how I got there. And once you read how I heinously got to this “random guestimate,” then answer and then we can press on to the next of my questions.


HERE ARE SOME NEW CONCETPS I HAVE LEARNED OVER THE INTERNET:

“A Quick Guide to Digital Video Resolutions and Aspect Ratio Conversions” wrote about how even some people who have been doing this professionally do it incorrectly and how there is a sampling matrix and an active area and it really does not work to just change the resolutions—like I have done. So I guess you can say really “WE ARE ALL LEARNING.” And the other concept that you should know is I do not have a “luminance meter” or whatever it is called to measure MHZ, so I have been using pre setup standards.

It is a very informative short article. Google it.


HERE COMES THE PROCEDURE:

The thing that is defined clearly in the article is the active image area for NTSC DVD including aspect ratio for PAR. But since my question deals with something not written in the chart, I have to make a random guess to what par is for 640 x 360. We have the par for 720 x 480 (710.85 x 486) in the article. But we need to figure it out for 640 by 360. And I am going to used my GUESTIMATE for the active image area (466 5/22 x 368)

Based upon the theory that NTSC has an active scanline length of 52 59/90 Microseconds, you can kind of guess the Width of PAR. And then try to match it with a common PAR and sampling rate in the chart.


52 59/90 x = 640
4739/90 x = 640
4739x = 57600
x = 12.15446296687065 which is closest to 3 types of standards: true compute square pixels, D2 standard for 525 line NTSC, or cropped true computer square pixels.

I just liked the sound of d2 so I said OK I will use the 12 3/11 MHZ setting from the chart

so:

52 59/90 (12 3/11)
4739/90 (135/11)

4739/18 (27/11)
127,953/198= 646.2272727272727

Therefore as a wild GUESS I could say the width of 640 in 640 x 360 is
646 5/22.

Now, I tried doing the same thing for the HEIGHT but I was looking at the pattern for NTSC width and the height basically stays at 486 except there is one height that is reduced by . But if I tried resizing using 486 as the height, I came up with a heinous calculation. So I was thinking to myself that since most heights are usually 4-8 more or less than the sampling matrix, then it probably will be something like 368.
I came up with something that had an OK solution, BUT maybe incorrect but is really feasible:

My guess for active sampling area for 640 x 360 is 646 5/22 x 368 .Now you know.


I will NOW be using 646 5/22 x 368 for 640 x 360 for NTSC. There will be NO resizing for HDTV. Just keeping it in letterbox 4:3 going to DVD NTSC 740 x 480 sampling matrix


First figuring out PAR since it is NOT in this guy’s chart:

Par = dar/sar
(4/3) / 646 5/22/368

(4/3) {368/646 5/22)
1472/1938.681818181818

= .759278797683524

Again, no resizing for HDTV. Just a regular par for 1.333333….
There is a calculator on the Internet that is helpful for this purpose that I found:

http://www.basic-mathematics.com/dec...alculator.html



Using bottom one here for PAR
323384/42651 = 0.7592787976835245 sounds like a great answer that is really close to the division but is off by a couple and that is why I underlined the end of the number. But we will use this fraction as the GUESTIMATE for PAR. Actually now that I am looking at the numbers it is a perfect match with an added number.

Now, following the procedure as outlined in “A Quick Guide to Digital Video Resolution and Apect Ratio conversions. Read the procedure or my numbers will be meaning nothing to you.

This is my work below: Please note I am not great at finding the LCM or GCF right away, so that is why it takes me so long.


Vertical ConversIon factor
486/368 = 1.320652173913044 or 243/184

The article mentions that anything other than 0.5, 1, or 2 may be because you are doing standards conversions between NTSC and PAL. Well, I am not really. It is a mp4 AVC with h.264 when demuxed becomes a 25 FPS pal frame rate. But let us not get into that yet.

Next step;

Horizontal Conversion Factor

(32384/42651) / (4320/4739)

(32384/42651) (4739/4320)

(8096/6093) (677/1080)

( 2024)/6093) (677/270)

(1012/6093) (677/135)

Now, taking the result from the above 2 and multiplying it by the Vertical Conversion Factor:

(685,124/822,555 ) )( 243/184) (v. conversion factor

(685,124 /274, 185) (81/184)

685,124 /30,465) (9/184)

(685,124 /3,385) (1/184)

(171,281/3385) (1/46)

(7,447/3385) (1/2)

7447/6770 = 1.1


NEW HORIZONTAL SIZE (width)

1.1 (640) = 704

NEW VERTICAL SIZE (height)

(243/184) (360/1)
(243/46) (90/1)

(243/23) (45/1)

(243/23) (45/1)
(10935/23)= 475.434783 or just 475

Thus 640 x 360 gets resized to 704 x 475


And then ADD BLACK BORDERS TO THE TOP AND BOTTOM

Horizontal is 704 and we need 720. So add 8 pixels to the left and right

Vertically is 475 and we need 480 BUT 475 is not a multiple of 2 so bump it up one number to 476. So we add 2. pixels to the top and bottom.

Hence:

LanczosResize (704 x 476)
AddBorders (8,2,8,2)

AddBorders(clip clip, int left, int top, int right, int bottom


Now, you may ask: Why does this look such like a good answer to me?
it LOOKS SO CLOSE TO THE HACK of 704 x 480. If so said hack version chops off some pixels maybe 476 would show these. Of course, I would not know since I am not a hardcore video person. This is just a wild guess from outside yonder. It also looked good because when I tried 352 as a height, I got something that was not so great

LanzcosResize(704,498)
Crop (0,18,0,0)
Addborders (8,0,8,0)

=NOT SO GREAT

Again, I am NOT looking for 16:9 yet. I just want 4:3

So my conclusion is that for NTSC is 640 x 360 the active image area is around 646 5/22 x 368 and the reason why that is is because it so close to the hack.


So, now you are asking: Is this a guide or a question? IT is a QUESTION simply because I want to know what the approximate value for the ACTIVE IMAGE AREA of 640 x 360 is and 2.) is my guess fair? If not fair, what is the active image area and show your work like the way I did it?


This is the first question. Ok I got to write my other questions with a different post.

Last edited by Gainnothing; 22nd November 2011 at 08:28.
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Old 22nd November 2011, 08:15   #2  |  Link
gyth
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Where is the 640x360 you are starting with coming from? Capture card??
You probably shouldn't be resizing vertically at all, but without more information about your source it is hard to say.
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Old 22nd November 2011, 08:35   #3  |  Link
Gainnothing
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Quote:
Originally Posted by gyth View Post
Where is the 640x360 you are starting with coming from? Capture card??
You probably shouldn't be resizing vertically at all, but without more information about your source it is hard to say.
640 x 360 Itouch video, not protected. Apple specs.

But I just want to find out the ACTIVE IMAGE AREA in a 480 x 360 sampling area. For example active image area for 720 x 480 is 710.85 x 486 in a NTSC system. The Target is 720 x 480 (710.85 x 486) for NTSC, DVD. The PAR in NTSC for this sampling matrix is 4320/4739.

My source is 480 x 360. My Par that I calculated PAR for NTSC 640 x 360 is shown in my posting and work:32384/42651. That is a rough estimate taking into effect that NTSC has a scanline length of 59 59/90 microseconds for the noticable part

Again I do not want to things the common way:

LanzcosResize(704,480)
AddBorders(8,0,8,0)

the reason for this is when the video is shown on TV it can cut some of the pixels hence I used:

LanczosResize (704 x 476)
AddBorders (8,2,8,2)

By guessing an active image area and then calculating the vertical, horizontal conversion factors and then the new height and width as explained in the article. But I just want to see what the correct Active image area is for 640 x 360 so I can caluclate the correct size instead of using the 704 x 480 version.

Again, I am asking this so things can be done better.



Thanks.

Last edited by Gainnothing; 22nd November 2011 at 08:58.
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Old 22nd November 2011, 08:37   #4  |  Link
vampiredom
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Wow. There is a lot of stuff there. Too much for me to process.

Quote:
I will NOW be using 646 5/22 x 368 for 640 x 360 for NTSC. There will be NO resizing for HDTV. Just keeping it in letterbox 4:3 going to DVD NTSC 740 x 480 sampling matrix
I really can't understand what you're getting at with this. I would assume anything that is 640x360 to be square pixel 16:9 (this assumption could be wrong, but you've provided no real information about your source other than the dimensions). So, to bring that optimally to widescreen NTSC DVD specs, resizing to 704x480 and adding 8 pixel borders to the sides would be correct, or as close to correct as you can come.

646 5/22 is a really strange number. I am guessing you got that from 640 * (486/480) ... That is just wrong. The "real" NTSC vertical resolution may be 486 but DVDs are 480, and PAR specs are what they are regardless. You could say that a DVD is a 720x480 "crop" of 720x486 area or, more accurately, a 480 height-crop with 8 extra pixels on each side that stick out beyond an area 704x486... or something like that.

NTSC widescreen is actually a tad wider than 16:9 ... that's why there are those 8 pixel borders you have to add. The 16:9 area is 704x480.

There will always be resizing for HDTV because the resolutions of 640x360, NTSC DVD and HDTV are not equal.

You can keep it letterboxed on 4:3 DVD if you want, but that will have less real pixels to serve up to the display. It is usually a good idea to use the widescreen PAR for widescreen material on DVD so as to maximize this.

If you really want the letterboxing, know that NTSC 4:3 PAR is 10:11.

640 * (10/11) = 704 x 360

So, the letterboxed 4:3 would be achieved by:

Code:
# I will also recommend Spline36Resize in instead of Lanczos
Spline36Resize(704,360)
AddBorders(0,120,0,120)
If you really hate the borders on the sides, you can go with 720x368 but, to me, it seems senseless to scale the image height from 360->368.

I hope this helps. Perhaps others will address your other points.

Last edited by vampiredom; 22nd November 2011 at 08:45.
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Old 22nd November 2011, 09:10   #5  |  Link
Gainnothing
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post deleted by user. I accidentally hit a button.

Last edited by Gainnothing; 22nd November 2011 at 09:28.
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Old 22nd November 2011, 09:26   #6  |  Link
Gainnothing
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Quote:
Originally Posted by vampiredom View Post
Wow. There is a lot of stuff there. Too much for me to process.



I really can't understand what you're getting at with this. I would assume anything that is 640x360 to be square pixel 16:9 (this assumption could be wrong, but you've provided no real information about your source other than the dimensions). So, to bring that optimally to widescreen NTSC DVD specs, resizing to 704x480 and adding 8 pixel borders to the sides would be correct, or as close to correct as you can come.

646 5/22 is a really strange number. I am guessing you got that from 640 * (486/480) ... That is just wrong. The "real" NTSC vertical resolution may be 486 but DVDs are 480, and PAR specs are what they are regardless. You could say that a DVD is a 720x480 "crop" of 720x486 area or, more accurately, a 480 height-crop with 8 extra pixels on each side that stick out beyond an area 704x486... or something like that.

NTSC widescreen is actually a tad wider than 16:9 ... that's why there are those 8 pixel borders you have to add. The 16:9 area is 704x480.

There will always be resizing for HDTV because the resolutions of 640x360, NTSC DVD and HDTV are not equal.

You can keep it letterboxed on 4:3 DVD if you want, but that will have less real pixels to serve up to the display. It is usually a good idea to use the widescreen PAR for widescreen material on DVD so as to maximize this.

If you really want the letterboxing, know that NTSC 4:3 PAR is 10:11.

640 * (10/11) = 704 x 360

So, the letterboxed 4:3 would be achieved by:

Code:
# I will also recommend Spline36Resize in instead of Lanczos
Spline36Resize(704,360)
AddBorders(0,120,0,120)
If you really hate the borders on the sides, you can go with 720x368 but, to me, it seems senseless to scale the image height from 360->368.

I hope this helps. Perhaps others will address your other points.
Article location:

http://lipas.uwasa.fi/~f76998/video/conversion/


My goal:
This video I have is letterboxed. My first step is to leave as it is, letterboxed, and just adjust for DVD analog tv. I do not want to advanced to HDTV yet. Of course, there is resizing for HDTV. What I meant is I am not ready to encode for HDTV YET. First step: see it on my analog screen as is. Next step: see it on same tv:full version. Next step after: HDTV So you jumped kind of 3 steps ahead of me and there was a communication error.

From article here are the specs for DVD NTSC

Sampling Matrix:
720 x 480

Sampling rate:
13.5

PAR:
4320/4739

Width in Microsecs:
53.33333

Active Image ARea Width:
710.85

Active Image Area Height:
486


There is no mention about 480 x 360 so based upon the chart I came up with a guess for the active image area.

Matrix:
640 x 360

My guestimate for PAR:


Par = dar/sar
(4/3) / 646+5/22 / 368

(4/3) {368/ 646+ 5/22)
1472/1938.681818181818

= .759278797683524
which apx equals rougly 323384/42651


My guestimate for Active image area width:

646 5/22 (look at the guys chart as it matches D2 standard)

My guestimate for Active image area height:
368

height usually does not change and most cases stays at 486 but is 243 for VCD qaulity. I have tried 486 as a height but got an ugly answer. Thus 368 sounded reasonable. I also tried 352 as a height and the width came height was almost in the 490's, so I kind of just killed that idea. 368 sounded reasonable but if you want to know the incorrect stats here they are:

HERE IS THE INCORRECT GUESS FOR HEIGHT USING 352

First figuring out PAR

Par = dar/sar
(4/3) / 646 5/22/352

(4/3) {352/646 5/22)
1408/1938.681818181818

= .72626667604511
30976/42651 will be the PAR for this TRY


Vertical Conversion Factor:

486/352 = 1.380681818181818 = 243/176


Horizontal Conversion Factor:

30976/42651 / (4320/4739)

(30976/42651) (4739/4320)

(30976/6093) (677/4320)

(3872/6093) (677/540) (divide by 8)

(968/6093) (677/135) (divide by 4)

(655,336/822,555)( 243/176) multiplying vertical conversion

(655,336/ 274,185) (81/176) (DIVIDE by 3)

(655,336 /30,465) (9/176) divide by 9

(655,336/3385) (1/176) (divide by 9)

(163,834/3385) (1/44) (divide by 4)

(81,917/3385) (1/22) (divide by 2)

(7,447/3385) (1/2) (divide by 11)

(7447/6770) = 1.1 Horizontal Conversion Factor


New Horizontal Size (width)


(1.1) (640) = 704

NEW VERTICAL SIZE (height)

(243/176) (360/1)

(243 /22) (45/1)

(10935/220 = 498

So in this example you would have resize to

704 x 498 so you would have to addborders to the left and right by 8.

Addborders (8,0,8,0)

And then we would have to crop 9 on the top and bottom

Crop (0,9,0,9)


Thus:

LanzcosResize(704,498)
Crop (0,18)
Addborders (8,0,8,0)

That was the ugly answer .



Here is the 368 for the height:

First figuring out PAR since it is NOT in this guy’s chart:

Par = dar/sar
(4/3) / 646 5/22/368

(4/3) {368/646 5/22)
1472/1938.681818181818

= .759278797683524

Again, no resizing for HDTV. Just a regular par for 1.333333….
There is a calculator on the Internet that is helpful for this purpose that I found:

http://www.basic-mathematics.com/dec...alculator.html



Using bottom one here for PAR
323384/42651 = 0.7592787976835245 sounds like a great answer that is really close to the division but is off by a couple and that is why I underlined the end of the number. But we will use this fraction as the GUESTIMATE for PAR. Actually now that I am looking at the numbers it is a perfect match with an added number.

Now, following the procedure as outlined in “A Quick Guide to Digital Video Resolution and Apect Ratio conversions. Read the procedure or my numbers will be meaning nothing to you.

This is my work below: Please note I am not great at finding the LCM or GCF right away, so that is why it takes me so long.


Vertical ConversIon factor
486/368 = 1.320652173913044 or 243/184

The article mentions that anything other than 0.5, 1, or 2 may be because you are doing standards conversions between NTSC and PAL. Well, I am not really. It is a mp4 AVC with h.264 when demuxed becomes a 25 FPS pal frame rate. But let us not get into that yet.

Next step;

Horizontal Conversion Factor

(32384/42651) / (4320/4739)

(32384/42651) (4739/4320)

(8096/6093) (677/1080)

( 2024)/6093) (677/270)

(1012/6093) (677/135)

Now, taking the result from the above 2 and multiplying it by the Vertical Conversion Factor:

(685,124/822,555 ) )( 243/184) (v. conversion factor

(685,124 /274, 185) (81/184)

685,124 /30,465) (9/184)

(685,124 /3,385) (1/184)

(171,281/3385) (1/46)

(7,447/3385) (1/2)

7447/6770 = 1.1


NEW HORIZONTAL SIZE (width)

1.1 (640) = 704

NEW VERTICAL SIZE (height)

(243/184) (360/1)
(243/46) (90/1)

(243/23) (45/1)

(243/23) (45/1)
(10935/23)= 475.434783 or just 475

Thus 640 x 360 gets resized to 704 x 475


And then ADD BLACK BORDERS TO THE TOP AND BOTTOM

Horizontal is 704 and we need 720. So add 8 pixels to the left and right

Vertically is 475 and we need 480 BUT 475 is not a multiple of 2 so bump it up one number to 476. So we add 2. pixels to the top and bottom.

Hence:

LanczosResize (704 x 476)
AddBorders (8,2,8,2)






And I am guessing no one here so far knows about Active Image ARea.

Last edited by Gainnothing; 22nd November 2011 at 09:52.
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Old 22nd November 2011, 09:50   #7  |  Link
vampiredom
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Seriously ... you are spending too much time trying to optimize an image for a $25 TV. The amount getting cropped off the sides has little to do with the "Active Image Area" for NTSC. It has a lot to do with the size of the bezel on the TV, the "action safe" area, the actual size of which varies from TV to TV. Usually, in video, editing, we would predict a 10% margin or something like that ... but something that is close to the edges may show up on one TV and not another.

I am actually familiar with the same spec chart you posted the link to. I am not saying he is wrong but the industry has greatly moved toward adopting the 10/11 PAR for 4:3 NTSC. Widescreen NTSC is 40:33. This is what all the video editing and animation programs assume. I am pretty sure it is also what is used when mastering film material for DVD, too.

If you want to keep strictly by the numbers you provided above, then it goes like this:
640 / (4320/4739) = 702.07

The height would stay at 360, because PAR gets applied only to the width here. That gives you 702x360 then... or 702x480... or 702x486 (but, since a DVD's picture is only 480 lines high, the 486 won't do you any good.)
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Old 22nd November 2011, 11:07   #8  |  Link
Gainnothing
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Quote:
Originally Posted by vampiredom View Post
Seriously ... you are spending too much time trying to optimize an image for a $25 TV. The amount getting cropped off the sides has little to do with the "Active Image Area" for NTSC. It has a lot to do with the size of the bezel on the TV, the "action safe" area, the actual size of which varies from TV to TV. Usually, in video, editing, we would predict a 10% margin or something like that ... but something that is close to the edges may show up on one TV and not another.

I am actually familiar with the same spec chart you posted the link to. I am not saying he is wrong but the industry has greatly moved toward adopting the 10/11 PAR for 4:3 NTSC. Widescreen NTSC is 40:33. This is what all the video editing and animation programs assume. I am pretty sure it is also what is used when mastering film material for DVD, too.

If you want to keep strictly by the numbers you provided above, then it goes like this:
640 / (4320/4739) = 702.07

The height would stay at 360, because PAR gets applied only to the width here. That gives you 702x360 then... or 702x480... or 702x486 (but, since a DVD's picture is only 480 lines high, the 486 won't do you any good.)

So as I take it you are stating that the width stays at 360. So the active image area JUST for the 640 x 360 would just be 640 x 360 and there is not an actual image area?

But I have tried using 646 5/22 x 360 and here are my results for converting to 720 x 480.


Par = dar/sar
(4/3) / 646 5/22/360

(4/3) {360/646 5/22)
(4/1) (120/646 5/22)

480/646.2272727272727


= 0.7427727368643173= 3520/4739

Vertical Conversion Factor:

486/360 = 1.35

Horizontal Conversion Factor:

(3520/4739 ) (4320/4739)
15, 206,400/22,458,121 (1.35)
=0.914085376955623=
20528640/22458121


New Horizontal
20528640/22458121 (640)
13,138,329,600 = 585.0146412515989

New Vertical
1.35 (360) = 486

Hence I get the UGLY, does not make sense numbers of

Reszie(585, 486)

Which DOES NOT MAKE ANY SENSE.

While using the active pic area of 646 5/22 x 368

I get

Resize(704,476)
AddBorders (8,2,8,2)



The other thing I think you are saying is that only horizontal changes matter.

If it did not matter then:

Resize(704,360) since it does not change.
But that would mean BORDERS would have to be added BIG TIME to = 480


So could you show me the calculations YOU would do for source (640 x 480) and target DVD NTSC 740 x 480:
Vertical Conversion FActor
Horizontal Conversion fActor:
New heights and width

And have that = to your theory 640 / (4320/4739) = 702.07

It is beddy bye time now

Time to get some rest.

Last edited by Gainnothing; 22nd November 2011 at 11:20.
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Old 22nd November 2011, 14:04   #9  |  Link
gyth
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Quote:
Originally Posted by Gainnothing View Post
640 x 360 Itouch video, not protected. Apple specs.
http://www.apple.com/ipodtouch/specs.html
It doesn't sound like you are using the 720p back camera, maybe the "VGA-quality" front camera?

Quote:
There is no mention about 480 x 360 so based upon the chart I came up with a guess for the active image area.

Matrix:
640 x 360
Do you have a 480x360 source???
Please post a non-resized sample.
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Old 22nd November 2011, 14:18   #10  |  Link
2Bdecided
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You're over thinking this, partly because this site...
Quote:
Originally Posted by Gainnothing View Post
...is wrong.

704x480 is a valid DVD resolution, and exactly* equals 4x3 or 16x9.

* - to within one pixel - and only mad people care about aspect ratio errors of less than one pixel.

Simply resizing 640x360 to 704x480 and flagging it as 16x9 in the encoder is perfect for DVD.


Plenty of threads you could have read...
http://forum.doom9.org/showthread.ph...t=aspect+ratio
http://forum.doom9.org/showthread.ph...t=aspect+ratio
http://forum.doom9.org/showthread.ph...t=aspect+ratio

Hope this helps.

Cheers,
David.
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Old 22nd November 2011, 14:47   #11  |  Link
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I've gone even deeper to answer this question before, haven't finished it though. My observation is this: standards are great, but what is really being used in the industry? To answer this question, I looked at the settings in various versions of Premiere or Final Cut, as these would be the programs being used to produce the DVD in the first place, so whatever setting was used in the program is the FACT of how the DVD is.

I also used a procedure where I measured the aspect of an HD and DVD version, by matching up images, and find the actual aspect, assuming the HD version is pure 1:1.

Finally, I looked at how particular DVD/bluray players and TV's display the image.

After going through all these steps and devices, there still isn't necessarily any standard being followed, unless it's pure HD 1080.
For example my LCD TV zooms up any analog/digital SD signals and changes the aspect, so it will never look quite right, even over HDMI!

As for your problem, what you can do is choose a suitable standard for future proofing, however your TV probably doesn't show the correct aspect at all, there is a way to fix this though. Look up your model and search for "service menu", if it's a modernish tube TV, there's a setting to adjust the horizontal size. I've tried to adjust my old tube TV to give proper aspect and minimum overscan. (Despite modern technology, my old tube tv had better colors than early LCD tv's by far, so even though it was low resolution, it was nicer to watch movies.)

Last edited by jmac698; 22nd November 2011 at 14:49.
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Old 22nd November 2011, 15:01   #12  |  Link
vampiredom
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Quote:
Resize(704,360) since it does not change.
But that would mean BORDERS would have to be added BIG TIME to = 480
Very true. Letterboxed 16:9 has pretty big borders.
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Old 23rd November 2011, 03:13   #13  |  Link
Gainnothing
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Quote:
Originally Posted by gyth View Post
http://www.apple.com/ipodtouch/specs.html
It doesn't sound like you are using the 720p back camera, maybe the "VGA-quality" front camera?


Do you have a 480x360 source???
Please post a non-resized sample.
It's a tv pilot. I do not have the rights by the producer.
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Old 23rd November 2011, 03:50   #14  |  Link
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Quote:
Originally Posted by jmac698 View Post
I've gone even deeper to answer this question before, haven't finished it though. My observation is this: standards are great, but what is really being used in the industry? To answer this question, I looked at the settings in various versions of Premiere or Final Cut, as these would be the programs being used to produce the DVD in the first place, so whatever setting was used in the program is the FACT of how the DVD is.

I also used a procedure where I measured the aspect of an HD and DVD version, by matching up images, and find the actual aspect, assuming the HD version is pure 1:1.

Finally, I looked at how particular DVD/bluray players and TV's display the image.

After going through all these steps and devices, there still isn't necessarily any standard being followed, unless it's pure HD 1080.
For example my LCD TV zooms up any analog/digital SD signals and changes the aspect, so it will never look quite right, even over HDMI!

As for your problem, what you can do is choose a suitable standard for future proofing, however your TV probably doesn't show the correct aspect at all, there is a way to fix this though. Look up your model and search for "service menu", if it's a modernish tube TV, there's a setting to adjust the horizontal size. I've tried to adjust my old tube TV to give proper aspect and minimum overscan. (Despite modern technology, my old tube tv had better colors than early LCD tv's by far, so even though it was low resolution, it was nicer to watch movies.)

Oooooooooooooh! Ouch! That is more work than I intended.


So I guess IF there is only 1 true standard, it really does not matter what way I am doing it.


I am going to READ the posting suggestions that the previous poster posted as suggested reading.


Now, please be reminded that I am NOT going to encode to my LED LCD yet. I just want to encode to my crappy but lovely Emerson 19" and not my Vizio 26" yet (but have had my Emerson since like 1992 and is reliable--therefore I am attached kind of to it--I was a pre-teen then).


But the reason why I do not want to encode it to see in on my LED LCD HDTV screen is because I like to take BABY STEPS (what about bob reference).


And you probably will hate me for this for asking: But is it safe to say Vertical resolution (there probably is not even a term for that--since it is more like vertical retrace for my analog) pretty much stays the same in NTSC Analog TV --480? So even if I wanted to make an old school SVCD I could just keep it has a height of 480? But when I have encoded SVCD and just randomly encode it to 480 x 480 quite a SIGNIFICANT AMOUNT of pixels on the left and right are chopped--for example--my name is Derek. And if you saw my name Derek in the credits in a 42 point letters it just says EK on the left. For example, when I was encoding a MAclolm in the Middle eppy, it did not say Frankie Muniz, it said ankie Muniz (beginning credits). No, that is not the current project I am doing.

But let me read the other few postings about resizing before I ask any more questions.


Ok. we now established that the article I have relied upon is asinine and wrong. So would it also be safe to say that the active picture of 480 x 360 is exactly what it says 480 x 360?

Last edited by Gainnothing; 23rd November 2011 at 03:59.
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Old 23rd November 2011, 04:15   #15  |  Link
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jmac698: I read one of the postings that were used as suggested reading and maybe the guy who wrote it was 1/2 true. I even see your reply.

According to scharfis_brain for my Analog TV set 711 x 486 represents the actual 4:3 image but since we cannot see the extra pixels on the screen the number becomes 702?

Because if I subtract 6 from both sides I would get 705 but that is not a great number therefore 704 x 480. How does 702 come into play? And how did we get 702?
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Old 23rd November 2011, 04:43   #16  |  Link
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Quote:
Originally Posted by Gainnothing View Post
How does 702 come into play? And how did we get 702?
I got it from you.

Quote:
Originally Posted by Gainnothing View Post
From article here are the specs for DVD NTSC
...
Sampling Matrix:
720 x 480
...
PAR:
4320/4739
If you accept that chart you posted as the authority, and 4320/4739 is your PAR, and you apply that 640 width, then

4320/4739 = 0.91158472251529858619962017303229

The reciprocal of which is: 1.0969907407407407407407407407407 * 640 = 702.07407407407407407407407407407

You can call it "702" for brevity. Most people would simply call it 704 because it is a better number to work with (704 % 16 = 0), an appropriate standard, and the result of using the industry-standard 10/11 PAR for 4:3 NTSC DVD.

Last edited by vampiredom; 23rd November 2011 at 04:53.
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Old 23rd November 2011, 05:08   #17  |  Link
Gainnothing
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Quote:
Originally Posted by vampiredom View Post
I got it from you.



If you accept that chart you posted as the authority, and 4320/4739 is your PAR, and you apply that 640 width, then

4320/4739 = 0.91158472251529858619962017303229

The reciprocal of which is: 1.0969907407407407407407407407407 * 640 = 702.07407407407407407407407407407

You can call it "702" for brevity. Most people would simply call it 704 because it is a better number to work with (704 % 16 = 0), an appropriate standard, and the result of using the industry-standard 10/11 PAR for 4:3 NTSC DVD.

By George I have something. RECIPOCAL. I was getting some strange 585 number but now that I did the inverse of it it does comes out 702


So if we take the POPULAR version now: 10:11


640 x 360 = 640/1 (11/10) =7,040/10 = 704

And also you like 704 because it is a MOD 16


SO let us bring in a RANDOM number so if we had:


352 x 360 = 352/1 (11/10) = 3,872/10 = 387 bump to 388 so maybe 388 x 360 ? but is not MOD16, so we would have to bump it up to _______? And just for the sake of fun IF you got this ugly number how would you bump it up to DVD? So in actuality I guess if you HAD 352 it should stay 352 x 360 and just blackborders be added?

Last edited by Gainnothing; 23rd November 2011 at 05:24.
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Old 23rd November 2011, 05:36   #18  |  Link
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Quote:
352 x 360 = … And just for the sake of fun IF you got this ugly number how would you bump it up to DVD?
That would depend on its PAR. If we assume it is 1:1 square pixels, and that 4:3 DVD is 10/11 PAR then it is easy:

(480 Target Height / 360 Source Height) = 1.333333333333 Scaling Factor

1.333333333333 * 352 Source Width * 1.1 Reciprocal of PAR) = ~516

So, that would be resized to 516x480

It does not matter that it is not MOD16 because you are going to pad it with AddBorders(102,0,102,0) anyway to make 720x480 ... unless it is not really square pixels to begin with, in which case all bets are off.

Last edited by vampiredom; 23rd November 2011 at 05:40.
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Old 23rd November 2011, 06:32   #19  |  Link
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Deleting and adding to bottom so you can see I added stuff

Last edited by Gainnothing; 23rd November 2011 at 06:45.
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Old 23rd November 2011, 06:37   #20  |  Link
vampiredom
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Quote:
So how would you calculate SVCD?
A 480x480 SVCD -is a 4:3 area squeezed into a square, so we can figure the PAR is 1.33333333333.

So...

480 * 1.33333333333 * 1.1 = 704

See how easy this stuff is?

** EDIT ** Oh, I was going SVCD -> DVD ... I read what you wrote incorrectly.

Quote:
480 x 480 with a source of 352 x 360
Ugh. I have had enough of this. Sorry.

Last edited by vampiredom; 23rd November 2011 at 06:39.
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