Using VirtualDub to Fix Aspect Ratio

[Djard]

Below is a guide I compiled for correcting the aspect ratio of a video. The steps work only if I do NOT recompress. But without recompression, a 700 MB file becomes a 135 GB file; and I almost run out of HDD space. Any ideas?

1. Launch VirtualDub -> File -> Open video file -> browse to and highlight the AVI -> Open.
2. Video -> Compression -> choose your favorite codec (in this example we will use DivX Pro v6.8).
3. Take note if the codec has format restrictions--e.g., with DivX, the screen size must be a multiple of 4.
4. Configure -> check "Use presets to configure the encoder" -> set to highest quality -> keep original bitrate.
5. OK -> OK.
6. Video -> Filters -> Add -> Resize -> OK.
7. In "Size options" section, check "Aspect ratio" option of "Compute height...".

NOTE: In our example, we will correct a movie wherein the
figures appear squeezed (e.g., narrowed faces), such
as when aspect ratio is 3:2 (1.50:1) but should be
37:20 (1.85:1)--i.e., 720x480 should be 720x390.

8. In the "Compute height from ratio" boxes, type in 37:20.
9. Adjust "Codec-friendly sizing" if required by the codec you choose to recompress the file in step 9.
10. Press "Show preview" button -> Hold down Shift key and drag progress controller to the right to view change.
11. Exit preview window when done.
12. OK -> OK.
13. Video -> Normal recompress.
14. File -> Save as AVI -> browse to save location -> Save.

NOTE: Minimize VirtualDub to speed up process (screen will
not need to be refreshed constantly).

15. Exit VirtualDub when done.
16. Browse to location of the corrected movie.

[jagabo]

Or, with Divx/Xvid files, open file in Mpeg4Modifier, set PAR/DAR flags, save. Done in seconds.

But without recompression, a 700 MB file becomes a 135 GB file; and I almost run out of HDD space. Any ideas?

Because without compression VirtualDub saves the file as uncompressed RGB.

[Djard]

Thank you so much. Does MPEG4 Modifier support only MPEG4 files in AVI containers, compressed with DivX or XviD?

[jagabo]

Mpeg4Modifier only works with Divx/Xvid in AVI.

[Djard]

Yay! I figured it out. I skipped the "Recompress" step and instead used "Full processing mode." It works, even though the remedy comes at the price of some video quality loss. Mpeg4Modifier may solve this problem.

[TJohns]

...I skipped the "Recompress" step and instead used "Full processing mode." It works, even though the remedy comes at the price of some video quality loss...

Of course, since filters are only used in Full Processing mode...if you'd set the Recompress mode *first* you'd have seen that the Filter menu is then disabled!

And the quality difference will now be due to the filters employed ... the Recompress option used before was still processing the compression stage.

Another tip - set VD to Fast Recompress mode, and inside the DivX codec settings you can do the resizing there ... it's more efficient (faster) than the VD resize filter & multi-threaded better too!

[Djard]

Thanks for the tip. I'm really grateful. I'm beginning to get the feel of VirtualDub. The GUI is so different from what I am used to.

[gonwk]

...
NOTE: In our example, we will correct a movie wherein the
figures appear squeezed (e.g., narrowed faces), such
as when aspect ratio is 3:2 (1.50:1) but should be
37:20 (1.85:1)--i.e., 720x480 should be 720x390.
...

Hi Djard & All,

I know this a 3 year old Thread, but I got to it when goo...ling it ... trying to fix a Video AR. Original Video was shot 2.35:1, the Encode is 1.8:1 ... meaning everthing is Elongated ...

I was trying to set the Resize filter ... I couldn't figure the math or the process ... so I just set the thing to Hard 720X304 and used the preview feature ... looked good so I went with that ...

Q1: But if anyone can chime in and tell me what is the correct way of figuring out the "Correct" Aspect Ratio and setting up the "Resize" Filter, I would appreciate it.

Q2: Is there a Standalone AR Calculator? Freeware of course!

MediaInfo shows Original Bitrate was 1105Kbps in Standard View, but under Tree View shows the Overall Bitrate to be 2149Kbps, I used H264 Compressor built in in VDub and set the Bitrate at 1500Kbps ... and I added about 200MB to the size of the video ... so!

Q3: Should I have left the bitrate at 1105 ... or 1200 or ... ? I know Garbage In Garbage Out.

Thanks,

G!

[jagabo]

https://forum.videohelp.com/threads/342827-Avidemux-aspect-ratio-question-%5Bfrom-newbi...=1#post2135805

DAR = SAR * PAR

If you're using square pixels PAR is 1.0 so the equation reduces to:

 DAR = SAR

With your example:

DAR = SAR
DAR = 720/304 = ~2.368

As for bitrates, every time you recompress with a lossy codec you will lose quality. So use as much bitrate as you can afford.

[gonwk]

Hi Jagabo,

Thanks for the Link & explanation. Hope everything is well with You!

G!

[Joeslacker]

Hello I had a quick question. What would be a good aspect ratio for a custom 800x600 recording.

[Baldrick]

Hello I had a quick question. What would be a good aspect ratio for a custom 800x600 recording.

It depends on the source....what do you record?

But what does this have to do with virtualdub aspect ratio?

[Joeslacker]

Hello I had a quick question. What would be a good aspect ratio for a custom 800x600 recording.

It depends on the source....what do you record?

But what does this have to do with virtualdub aspect ratio?

I record world of warcraft footage in 800x600. Just wanted to know what a good aspet ratio would be for something like that. I also need help with adding of multiple songs in virtualdub to my video. But, that may be for another thread.

[jagabo]

i record world of warcraft footage in 800x600... What would be a good aspect ratio for a custom 800x600 recording.

4:3 dar. 1:1 par.

[Djard]

800 divided by 600 = same as 4 divided by 3 = 1.33 = letterbox.

Regarding "...what is the correct way of figuring out the 'Correct' Aspect Ratio..."? There is probably a better method, but I have gotten decent results with the following approach:

Preview the picture -> Search for a familiar face or object, like a wheel -> Adjust the AR until the face or wheel appears round.

I used MS-Word and a graphics editor to create a library of images that can be compared to any video for a good idea of what the DAR is. Attached are a couple of the images that can be easily resized to the video size with a handy app like freeware IrfanView. Nothing amazing and maybe primitive. If anyone wants a copy of my library, I'll be happy to share it--AR from 1.25:1 to 2.90:1 (21 images).

Edit: Oops! maybe I need permission to upload a *.png file as I did not get a confirmation of a successful upload, nor did I see it in the post after submission. Sigh!

[manono]

800 divided by 600 = same as 4 divided by 3 = 1.33 = letterbox.

Pillarbox, maybe, on a widescreen TV set, but not letterbox