Adjust dimensions of DivX movie in VirtualDub

[dimitrik]

Hi there,

I have a DiX movie which has a resolution of 352x233. I want to re-compress this in DivX, but DivX (or the current versions anyway) only accept movies where the height is multiple of 2 and width a multiple of 4.


So I think the bst thing is to add a black band to my movie, 1 point thick - this will allow me to encode with DivX without losing any part of the image.

Is there a way (I'm guessing filter?) to do this? I tried some virtualDub filters like resize but they also change the picture resolution and apply various re-size algorithms - there is no setting to leave the image alone and just add the black band.

Is there a way to do this in VDub (or another program)? I'd be grateful.
Thanks,

Dimitri.

[Enchanter]

Check out Avisynth Scripting. It has a feature called AddBorder that you should find useful.

[setarip]

"Is there a way (I'm guessing filter?) to do this?"

Sure there is (But I really think you're better off just resizing to 352x232, as you'll never be able to discern the loss of that 1 pixel thick line):

(In VirtualDub, set "Video" to "Full Processing Mode" and "Audio" to "Direct Stream Copy")

1) Load you video into VirtualDub
2) From the "Video" dropdown menu, click on "Filters", then click on the "Add" radio button and doubleclick on the "Resize" filter
3) Set "New width" and "New height" to the SAME resolution as your original .AVI (In this example, I'm assuming it's 720x480)
4) Put a checkmark in the box labelled "Expand frame and letterbox image - and enter a multiple of 16 in "Frame height" (Perhaps 208, or 192 to approximate 16:9 - which, in this example, will increase the height from 480 to 688 or 672)
5) Click on "OK" to return to the "Filters" window

6) Once again, doubleclick on the "Resize" filter
7) Set "New height" to 480 (This will reduce the ENTIRE image, including the black bars to 480 pixels of vertical resolution). Click on "OK" until you get back to the main VirtualDub window
8) Save with a new filename

[dimitrik]

Thanks for the detailed instructions - its really helpful

I think understand them except for two questions:

1) Do I need the 2nd part of the instructions (from 6 onwards)? I don't understand that part, won't that just distort the picture by 'squishing' it flat?

2) If I leave the original resolution unchanged in the resize filter does that mean that the algorithm used doesn't matter (Nearest neighbor is default) - I'm guessing that it doesn't.

Thanks again!

[setarip]

"Do I need the 2nd part of the instructions (from 6 onwards)?"

Yes...


"won't that just distort the picture by 'squishing' it flat?"

No, because - This will reduce the ENTIRE image, including the black bars to 480 pixels of vertical resolution...

[dimitrik]

Well, I tried it with the instructions from step 6 onwards - that resulted in a distorted picture, so I must have misunderstood you or done them wrong. I was a bit confused by the reference to 720x640 - why would that be the original resolution?

Anyway, without the instructions from step 6 on, it worked fine...

So actually, it was very helpful advice - thanks! I've now got a file that's indentical to the original but compatible with DivX so I can encode it.

Thanks again!

[setarip]

"I was a bit confused by the reference to 720x640 - why would that be the original resolution?"

As I stated, all of the resolutions I referred to are only examples



"So actually, it was very helpful advice - thanks!"

My pleasure ;>}

[dimitrik]

"As I stated, all of the resolutions I referred to are only examples"

Sorry, my brain must not be working - it's late here...