Tips: Letterboxing 101 - Make your video look like film!

Letterboxing 101

On this page we're going to discuss how to achieve the widescreen aspect ratio for your videos. The specific techniques are geared for use with Adobe Premiere and the RT2000, but you should be able to adapt these methods for use with other editing software.

Background:
The aspect ratio of most common televisions is 4:3 with the width being 640 pixels and the height being 480 pixels. 4:3 refers to the ratio between the width and the height. (Note: DV format uses 720x480 pixels, but is still 4:3 because the pixels are not square.)
Motion pictures are typically shown in a wider aspect ratio (ie. widescreen), with the most common being that of 16:9.

There are two ways to fit and display a widescreen image on a 4:3 monitor or display. The first method is called "letterbox" format. Bars are displayed on the top and bottom of the image, while the image is displayed in "widescreen". The other method squeezes the wider picture horizontally into a 4:3 ratio. This can be done through an "anamorphic" lens, or digitally in the camera.

Pictures are shrunk proportionally by 50% to make them faster to download.

This picture is an anamorphic picture as capture by a GL1 camera. Notice how the picture is squeezed horizontally. Picture is 720x480.

This picture is the same anamorphic picture "stretched" to fit a widescreen television. Notice that the height is the same. Picture is 960x480.

This is the same picture adjusted to be displayed correctly on a 4:3 display. Notice that the width is the same. Picture is 720x480.

What to do if you have footage shot in "Widescreen" mode:
If you have footage shot in widescreen, or anamorphic, mode you'll have to convert it to letterbox unless you have a widescreen television or monitor. We accomplish this by squashing the video vertically. We'll maintain the width of 720 pixels (or 640) and compress the image vertically to 360 pixels. Premiere does not have any "built-in" feature or filter to help us. Fortunately though, the RT2000 does. I'll be discussing the use of MVT2.0, but if you are still using MVT1 you can download our widescreen filter to achieve a similar effect. Download here.

In Premiere 6.0 you'll find the "Effects" palette. For our purposes we are interested in the Matrox 2D/3D DVE filter. To apply this filter to a video clip in the timeline just select the effect and drag and drop it on the clip.

In Premiere 5.1c you'll apply the filter by right-clicking on the clip and selecting "Filters..." from the context menu. Choose the filter and click "add".

Once the filter opens up you'll see the above interface screen. In the "Special Effects" directory you'll find the "Dud effect". This effect is our best friend. Before you do anything else you'll want to click the "Allow changes" button and slide the "Softness" setting to zero. Next we'll move to the transform tab where we can do our real work.

The "Transform" tab of the RT filters is where all the power lies. The key to our letterboxing is in the "Size" attributes. Unselect the "Fixed aspect ratio" box under the "Size" setting. Now, we'll use the "Y" setting to vertically compress the picture to get the aspect ratio we want. It just so happens that setting the "Y" to 75% we get a perfect 16:9 ratio. (360/480=.75). So, just enter 75 into the "Y" box and you're good to go. Almost. You'll need to copy the keyframe you just made and paste the settings to the other keyframes. If you don't want to mess with that you can download our Anamorphic Widescreen Settings. To apply the settings just hit ctrl-o and select the file.

If all of your footage is shot in anamorphic mode I suggest that you edit it normally in Premiere and create a "Virtual Clip" to which you can apply the filter to. That way you only have to set up the filter one time.

What if my footage is shot in 4:3, or normal, mode? How do I create a letterbox look?
This is the part that I assume will be of interest to most people. This method is fairly simple and does not require any filters to accomplish. As far as I know, this effect can be simulated on almost any editing platform or system.
We create the letterbox by placing a graphic file over our video clip. The file (a TGA, in this case) is 720x480 pixels (or 640x480 depending on your system). It is solid black with a 720x360 transparent alpha channel. You can download the file here.

This was shot with a GL1 in normal mode. Picture is 720x480.

This is what I want the video to look like. By placing a black graphic with a "widescreen" transparency over our clip, the "Widescreen" portion shows through. The picture is still 720x480, but the video is visually cropped to 720x360.

Here's how to do it:

In the timeline you'll put the "letterbox.tga" file on the very top track. Here you see it on the "Video 2" track, but it can be any track as long as it's on top. Since it's a single frame file you'll want to stretch it over the whole area you want to letterbox. Next we'll turn on the transparency of our file.

Select transparency for the "letterbox.tga" file and choose "Alpha Channel".

Now this works really well as long as the "good" part of your video is in the center region, since the top and bottom will be cropped. By using the RT2000 "Dud" filter you can adjust the picture's position up or down behind the letterbox frame. In other words, you can frame your shot. By using keyframes you can even move the framing around. If you don't have the RT2000 you can use the "Video Motion" filter in Premiere.

Hopefully this gives you some ideas on how to achieve the "letterbox look". If you have any questions, comments, suggestions or think I should add or clarify something please let me know.

Ashley Guy
video@guygraphics.com