How do I Maintain the Right Aspect Ratio?

[lexxprime]

How do I maintain the right aspect ratio when normally you have for instance 720x576 and on a kvcd you change it to 352x576 doesnt the picture aspect change??

Lexx

[incredible]

If u use moviestacker or FitCD to calculate the right resizing it will add the right borders so the correct aspect ratio will be maintained.

Also u could use GripFit (also supported by moviestacker), .. so have a look at DialHots optimal scripts where u can see how the GripFit-Lines work.

I wouldn't change the aspectratio of the original, ... in case of widescreen (2.35:1 incl. big borders on top and bottom) leave it as it is, cause you'll have less active pixels on every frame to encode and therefore on the same mediasize the quality will be more preserved. And thats what also GripFit does ... it maintains the orig Aspectratio.

[Boulder]

The aspect ratio won't change as your DVD player stretches the video accordingly. This is why the lower resolution produces a less sharp picture.

[russiansexpat]

So, the rule of thumb is don't change original aspect ratio, correct? I assume that original aspect ratio is just width/height of the source (mpeg files can store aspect ratio information, avi files can't).
Thats what I do to make things simple and to avoid pitfalls:
scale (original) width to target width, in the same time scale
heigth using _original_ aspect ratio.
after that expand height to targeted height. Expand means to add balck bands, but don't stretch.
If the height can't be expanded (means it is greater than targeted height already) then it is a bad luck - just change your target width and/or height.
To view result on monitor, you can specify aspect view in your software player or zoom.
Is this a right way to be sure that the result will be viewable correctly on standalone DVD player/TV? (my understanding that pixels are not square, so how they viewed depends on TV or monitor or whatever).
I am asking these questions (maybe trivial for you), cause in the beginning it is easy to make mistakes and I see the source sometimes coming from smart numbnuts who are chopping heads and legs from the movie trying to fit it to 1:1 aspect or other what they consider as a standard.

[incredible]

In case of encodings refering to aspect ratio read this:
www.incredible.de.tf/aspectratios.html

There you'll see what happens when using Moviestacker for Letterboxing or what happens when your player resizes the height on anamorph DVD 2.35:1 Sources to receive a 2.35:1 view on a 4:3 Tv.

[russiansexpat]

Thanks for you link.
DVD player use original height as a base. It scales the height, expand it and then chop left and right. Still after we have black bands.
I use original width as a base, and don't use crop (chop) function at all. It works fair when I convert to VCD resolutions:
352*288 and 352*240. Not so good when converting to SVCD resolutions: 480*576 or 480*480 - black bands are too big, so I have to use software zoom of my mplayer (I don't alter the result).

Quote:

The stand alone player now reads the aspect ratio information of the videostream header and performs..

My question is how do I put correct aspect ratio into mpeg?
Also, aspect ratio for my source is unknown as it is AVI file.
How do I calculate it?
(I don't use movieslacker, I keep my house m@#$%oft free.)

[incredible]

Quote:

(I don't use movieslacker, I keep my house m@#$%oft free.)

???? Is moviestacker microsoft??? No!
In your case I shurely would use Moviestacker!!

Quote:

My question is how do I put correct aspect ratio into mpeg?
Also, aspect ratio for my source is unknown as it is AVI file.

You can set in the encoder 4:3 if you encode non-anamorph (regulary) or 16:9 for anamorph (width will be maintained sqeezed if your sources width is also sqeezed!). In case of Avi Files like Captures or Dvix/Xvid 99% aren't anamorph! Because the don't appear squeezed in their width!

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How do I calculate it?

Moviestacker or FitCD

[Dialhot]

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Originally Posted by incredible

???? Is moviestacker microsoft??? No!
In your case I shurely would use Moviestacker!!

He probably mistaken moviestacker with moviemaker.

[Abond]

I will try to clear a bit the mystery with aspect ratios. In some aspects I can be wrong, then excuse me in advance .
The 4:3 TV shows the picture in aspect 1.33:1 (4/3=1.33(3)). But 720x576 is not 1.33:1 at all, it is 1.25:1. Therefore the player keeping the vertical resolution at 576, stretches the horizontal to 768! The same is with vertical resolution at 544 (still low stretching to 76, 480(middle stretching) and 352 (high stretching). So it correspond to the quality of the picture - better with low stretching and worst with high. For 352x288 the player stretches the picture in both directions - to 768 horizontal and 576 vertical - that is the worst scenario and correspondingly we have the lower quality picture.

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My question is how do I put correct aspect ratio into mpeg?

If you put the same width and height as the avi the aspect will be correct, but not on the TV.

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How do I calculate it?

Read here question 62 and maybe 63. I think you will get it.
BTW the black bands at VCD or SVCD resolutions are absolutely the same...

[incredible]

Totally correct PAL would be 702x576 and as it should be devidable by 8/16/32 therfore the legal standard became 704x576 quadrapixels!!! And these 704x576 will be stretched in their width to square pixels (PC=768x576) on TV so the AR will be viewn correct.
720x576 in real is also (8+704+ x 576 ... if the options in Moviestacker are set right .. you will see this at the calculations.

[russiansexpat]

Thanks for your help again.

Yes, avi are not anamorph, they don't store aspect information for player (software or hardware); on the other hand, vcd and svcd use anamorph and mpegs hold information for player (software or hardware) how to scale them.

I was totally wrong. I realised it when I watched test vcd and svcd .bin with disabled aspect compensation in my software player. They appered ugly..
So, I need to clean a mess in my scripts where I need to put back aspect variables and calculations.