Resizing MencodeMe - MenCalc comparation
 

Hi: I'm comparing both tools resizing but there are something that I don't understand.
Can anybody here explain me how interlaced resize modify normal resizing values, and how 16:9 to Letterboxed modify normal resizing values? (How to apply this to formulas or scripts (i.e. divxresize by VMesquita))
When we must to use 16:9 to Letterboxed 4:3?

I don't use any of these tools as you know but I can answer to you in a general way, maybe that won't fit to the situation :

- interlacing : the only way that this can impact the resizing is when you split the fileds to work separately on odd and even fields. In a frame of 480*576 you have 2 hald frames (fields) that are 480*288. That are these values that you use in the resize line.

- 16:9 to lettterbox. To use correct words : anamorphic -> non anamorphic.
You take the original height of the source (that is anamorphic), you multiplicate it by 3/4 (not sure of the value, too tired to do the maths ;-) but the idea is correct) and you add black borders to compensate. The width does not change.

- you never MUST to do 16:9 to 4:3 letterboxed. You DECIDE to. It's your choice. Except when you encode in VCd res because the DVD does not support anamorphic picture for this resolution, so you must produce a 4:3 letterboxed video.

I still don't understand difference between 4:3 and 4:3 letterboxed.
I only see in MenCalc when I mark interlaced box, in NTSC not change in crop and expand and only a flag in scale change (:: to :1:). But in PAL, width and height values change.
About 16:9 to 4:3LB res values change.
Could you help me to understand that? (Maybe you can download MenCalc, it takes only few seconds, http://home.arcor.de/packshot/mencalc1.01.0.exe )
Thank you.

4:3 is a Full Screen movie, where there are no black borders and the movie takes the complete screen.
4:3 letterboxed would be the case of as a Wide Screen movie with black borders, but encoded as 4:3 aspect. So in this case, your actual film pixel area is a 16:9 area, encapsulated by black borders.

-kwag

Hi Kwag, how many time, please to see you.

1 - I understand that, but I want maths to build a resize calc tool.
2 - Why when I encode from avi, I select 4:3 (not 16:9 to 4:3 LB) values in MenCalc, and result is a mpg with AR ok and black bars. And when I select 4:3LB values, mpg don't have correct AR. (it seems a 4:3 between black bars, hehe).
3 - Will it be that when I select 16:9 to 4:3LB, I must to select aspect=1.7777?
4 - I will do some test with different combinations.

Hi Prodater,

Ok then, all your answers with full math are here ;)
http://www.uwasa.fi/~f76998/video/conversion/

-kwag

That should be the opposite (I you have already understood). So either there is a bug in mencalc (I don't think so), either you forget to force the A/R to 4:3 under your player (you don't use wmp, do you ?)

aspect=1.7777 is the way the mencoder designer decide to use to tell to the encoder to set "anamorphic" flag to ON in the mpeg2 stream. Very clever, isn't it ? :-(

There is no diff in the picture produced itself between aspect=1.3333 or aspect=1.77777..

As I understood, it should be. For this reason it surprise me, and don't understand. But encoded mpg is fine.
I use BSPlayer (shift+3 option when playing). But I see it in my standalone also!
Mencoder settings aspect=1.3333, scale, crop and resize from MenCalc, without mark in interlaced neither 16:9 to LB 4:3.
When I tested last one, as I said, it was like a 4:3 with a black frame.
But another question, with TMPGEnc I don't remember set a flag 16:9 to 4:3LB. I only set 4:3 625 PAL fullscreen center as output, and don't see nothing about letterbox.
But anyway, it is right so, and I don't understand why?
Moviestacker give me similar values and don't ask me 4:3 4:3LB, it only takes pixel frames, as MenCalc, and give me correct values (maybe no matter differences).
My question still. What math to apply to MenCalc normal values, to obtain interlaced values (only changed in PAL) and to obtain 16:9 to 4:3LB values.

Drop mencoder ;-). Just kidding...

The letterboxing is handled either by the avs script (command addborders) or with the "arrangement method" in tmpgenc. If you set it on "fullscreen, keep aspect ratio", tmpgenc will create the correct black borders to "keep aspect ratio" as you asked to it.

Your wrong ! If you don't check the anamorphic box for the "destination", moviestaker produces parameters for letterboxed image. If you check this bos, you will see that the borders are reduced and the height of the image prioduced (in the resize line) is increased !

I answered to you for all taht in my first post. Read it again.

Well, I take a look again and you are right. When in BSPlayer I select 4:3 4:3LB encode is ok.
But in my 4:3 TV, when I set in my standalone to output 16:9. Both samples (4:3 and 4:3LB) look ok, but if I set output = 4:3 LB or 4:3 LS, 4:3 encode looks ok, but 4:3 LB not.
How is it?
And how it is better to encode then, 4:3 or 4:3LB?

Now, your last post makes me a bit confused as Phil already stated all needed Facts.

IF you deal with an "NON"-Anamorph Source (almost 99% of all Xvid/Divx/mpeg4 are) you never use letterboxing to 4:3 as it (as already stated) just squeezes the sources heigth by 1.333 (or multiplied by 0.75) this makes an ANAMOPRH Source NON-Anamorph and the needed Black borders to fit 576 height will be added by Expand.

I dont reencode that much PAR 1:1 mpeg4s but I did a test workout on a 544x288 (as I remember the sizes right) Testchart and had a PN exchange with phil. A Comparison by using Photoshop showed that Mencalc works right, in case of 528 or 544 Output even more correct than MS as MS uses a wrong destination PAR when doing the calculation for 528 or 544 outputs.

And in case of ANAMORPH Sources like DVDs a Letterboxing to 4:3 gives ...

PRO: Less effective Moviearea :arrow: faster filtering on only active pixels :arrow: less active Pixels for the mpeg algorhythm to handle :arrow: more compression.

CONTRA: Less Pixel Detail reserves for a playback on a 16:9 TVset or even a 1024!! width (effective Pix) Beamer Playback Device as in such a case the width will be just scaled by 1.333 (or devided by 0.75) and the height will be KEPT! And as the Height is most responsible for sharpness this is the gain of anamorph encoding for 16:9 TV Sets - not to stretch the height.

I only had descripted what I saw. Maybe you (or who want) can do a test.
Take an avi sample. Make a single command line for mencoder with scale, crop and resize values gived by Mencalc, set aspect=1.3333. Burn this sample in a CDRW and see it in a 4:3 TV, but setting in your standalone 16:9 output. If it is correct for all standalones, we will obtain more quality, as film pixel is lower (as you said multiplied by 0.75), bitrate will can rise.

In sum, you encode in 4:3LB (black bordes are added to compensate the A/R of the source and generate a 4:3 image with not distort).

Then the image is distorted by the player ! I really don't see how you can obtain a correct picture like this.

It is definitely not. Your player has a strange behaviour that is not common to all ones. Mine has also a stange behaviour but it is the opposite : all VCD are outputed in 16:9 even in they are 4:3, and I have to force the TV in 4:3 mode to watch them...