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Windows Movie Maker

Understanding Black Borders


Windows Movie Maker (WMM) does a pretty good job of maintaining the proportions of video files, but it often leaves you with unwanted black borders in your newly saved movie. This article will help you understand why and how to remove those you don't want.

Typical Issue and Resolution

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A video gamer posted and emailed about Windows Movie Maker (WMM) adding unwanted black borders to what he posted on YouTube. He was recording game segments as video clips sized at 1440x900 pixels, editing them in WMM and then saving the movies with a custom profile that preserved the 1440x900 pixel dimensions.

He sent a sample clip and I spent an evening studying the issue and how to work around it... here's my response

His closing post was "yep that did it, thanks for all your help : ) "

Let's take a deep dive into the subject and use this example as a reference. Your issue might start or end with different pixel dimensions.

Video Clips as Source Files

Video clips come from many different places.

Digital videos can have square or rectangular pixels. The DV-AVI files from mini-DV camcorders are great examples. Those from NTSC camcorders use rectangular pixels of 720x480 dimensions. When 'tagged' as standard 4:3 proportions, the pixels are squashed so the file is viewed at 640x480 pixels. When 'tagged' as widescreen 16:9 proportions, the pixels are stretched so it's viewed at 856x480 pixels. When watching a video you don't know if you're seeing square pixels or rectangular ones, or what planned distortions are being used by the player.

Sometimes video clips used in movie projects already have black borders... embedded by the cameras that shot them or a previous edit or conversion process. Those borders need to be cropped out if you don't want them.

The first step in dealing with unwanted black borders is to look at the source files before importing them to a WMM project. Check the pixel dimensions and see if there are embedded black borders. I typically use MM2.6 or VirtualDub to take a frame snapshot and then study the snapshot.

WMM Settings.... adapt to what you can't change

WMM has two viewing modes... standard 4:3 and widescreen 16:9. You must pick one or the other and accept any distortions you see in the editing phase.

Before starting a WMM project think about the aspect ratio and pixel dimensions of the movie you'll be making. HD movies are usually widescreen 16:9. Standard definition ones can be either 4:3 or 16:9.

If you're heading to something that doesn't align with the usual aspect ratio or dimensions, as the game player in the above example, you'll need to plan on using a custom profile. Rather than getting into that subject here, see my website's (www.papajohn.org) Windows > Movie Maker > Publish and Save page. It includes info about using custom profiles in WMM.


Example - Unwanted Black Borders... made with WMM

My brother sent a pack of 5 DVDs with MPEG2 files, all standard aspect ratio (4:3) with pixel dimensions of 730x480. As I prefer editing with .wmv files I at first did file conversions with the widely used Freemake Video Converter, accepting the easy option to make the new files the same as the originals.

When I noticed the black borders I realized the MPEG2 files use rectangular pixels and the conversion to wmv was creating files with square ones. WMM handled the MPEG2 file OK as it knew how to tweak the pixels, but considered those in the wmv file to be square.

I opted to make the new files 720x540 pixels to preserve the quality and get square pixels of the right overall 4:3 aspect ratio.


The Editing Phase.... and Project Previewing

The simplest movie project is one where you're trimming the ends off a single clip that has a 4:3 or 16:9 aspect ratio and the usual pixel dimensions, and republishing it to a same or similar sized file. What you need to do is be aware of any unwanted black borders at the top/bottom or sides. If you see them, check the view tab and the aspect ratio for the project. It might be as simple as toggling it to the other choice before publishing.

A more complex project has a mix of different shaped and sized video clips and still pictures. WMM will try its best to keep them all looking good, adding black borders as needed. Those borders will be embedded in the frames of your saved movie and show up online at YouTube or on your DVD. If the overall movie looks OK but you see a picture or video clip with black borders you don't want, you'll need to crop/resize/reshape the source file as needed. It's usually easy to do.

Extremely off-usual sizes are not handled well by WMM. Two of my test wmv files fall into that category. One is a 850 pixels wide by 80 pixels high and the other is 162 wide by 890 high. WMM distorts them both in the preview to fill a standard 4:3 sized window and adds black borders to the side of a widescreen 16:9 window. It does the same with still pix of those dimensions.

Saving the Movie

WMM has two basic aspect ratio settings which you have to work with - standard 4:3 and widescreen 16:9. Depending on which one you are using for the project the various sized clips will have different black borders added.

For good or bad, the saved movies tend to look like the previews. By bad I mean my two really odd-shaped wmv files are extremely distorted to fill standard 4:3 sized frames. By good I mean that most source files seem to fit OK in the saved movie, assuming you don't mind the black borders.

A final comment about the black borders. Pure blackness has RGB values of 0, 0, 0. The blackness that all versions of Movie Maker produce in the saved movies is 16, 16, 16.... almost pure black.

Viewing Saved Movies....

The goal of all video editing is to watch it... I find the digital world interesting. Unlike the analog world where I can use a magnifying glass to see what's on a movie frame, in the digital world I have to use a software viewer.

Be aware that any issues you see in the final movie could be due to the player... don't blame WMM or the saved file, at least not right away.