VDub resizes my videos (even when I don't ask).

[BassKozz]

How come when I "Save As..." with VirtualDub Mod it resizes my videos?
Even when I am not using any filters or compression settings.

Here is a screen shot of the video prior to VDub:



And here is a screenshot of the video after VDub:


I know there is nothing in the VLC screenshot but it is just to show you the display sizes.
p.s. the videos I am running thru VDub are VHS captures @ 352x480.
Please help out a newb.
Thanks,
-BassKozz

[Baldrick]

what is the source video frame size? the mpg is probably resized to correct aspect ratio, it can be for example 352x480 with 4:3 aspect ratio.

[BassKozz]

what is the source video frame size? the mpg is probably resized to correct aspect ratio, it can be for example 352x480 with 4:3 aspect ratio.

Yah there 352x480 VHS capture files (MPEG2)... why does it change the aspect ratio?
Is that a good thing? For viewing on TV? For viewing on Computer?

[Baldrick]

You could set the avi display aspect ratio to 4:3 with mpeg4 modifier....but many players will ignore it.

So I would resize to a 4:3 resolution like 352x264.

[BassKozz]

Baldrick,

Thanks for the help, but I am still confused.
Should I resize to a 4:3 res (352x264) for Computer Viewing or TV viewing?

Is there a way to keep VDub from changing the aspect ratio in the first place?
Why does the aspect ratio need to be changed?
I liked the video fine how it was.

Thanks,
-BassKozz

[Cornucopia]

Let me explain it another way...

Vdub only saves as AVI.

You're starting with an MPEG, so you'll have to convert (no matter what).
Therefore, no such thing as "Direct Stream Copy" this way.

Next, MPEG2 fully supports the DAR flag in its bitstream, and most players that work with MPEG2 fully recognize that flag.
However, AVI (the container) doesn't really support the DAR flag (most notable exceptions being DV and MPEG4 variants--where it's within the video stream, not the container), and players hardly ever expect AVI's to have the DAR flag, so it really isn't recognized.

IOW, your MPEG source is STORED in that squished format, but DISPLAYED stretched back to normal. In converting your MPEG to AVI, you have destroyed the flag that tells the player to stretch, so it is showing it in its square-pixel-equivalent squished (stored) format.

How to fix this: (only 2 good choices)

A. Add back the DAR flag (if you're saving as DV or DivX, Xvid, or other MPEG4, etc) (or try encoding again correctly WITH the DAR flag) and use only players that recognize DAR flags in AVI files (rare)...

or

B. Resize, making the assumption that the AVI players will be expecting square pixel material.

or

C. Crop aka Pan & Scan (don't do this please)

Scott

[BassKozz]

Thanks Scott,

Now it's starting to make sence.
Can you explain how I'd go about fixing this with options A & B ?

[jagabo]

To keep the frame size and display as 4:3, go to the Xvid configuration dialog and set the Picture Aspect Ratio to 4:3.

To resize, use Video -> Filters... Add, select the Resize filter and set the frame dimensions to a ratio of 4:3, eg, 640x480, 320x240, etc.