Dealing with 16:9 and 4:3 Aspect Ratios

Posted on by Larry

[ This article was first published in the April, 2009, issue of
Larry’s Final Cut Pro Newsletter. Click here to subscribe. ]


I’ve gotten a lot of questions about this issue recently. Each is a variation on what Trent Anderson sent in:

I am producing a documentary, and most of the footage that I have from years back, is 4:3., and so recently I have been shooting some interviews, and again, I choose to use 4:3 instead of 16:9, so that all of the footage would match up. However, I have noticed that most new stuff now, especially if I am going to submit it to a film festival, or TV, would prefer 16:9. I have tried to drag the old 4:3 clips into the timeline, with the sequence presets to Anamorphic, but still with NTSC 4:3. I think it looks a little “squished” or stretched. Any suggestions as to how I might accomplish this? Thanks so much for any input.

Larry replies: Trent, thanks for your question.

The basic problem is that both 16:9 an d4:3 footage has exactly the same number of pixels in the image. The only difference is in the shape of the pixels. 16:9 pixels are short and fat, which 4:3 pixels are tall and thin. (For the engineers in the audience, allow me some dramatic over-simplification.)

If you edit 16:9 material into a 4:3 timeline, FCP will always scale the image so that the entire image is displayed. (In fact, for EVERY video format, if you edit a larger image into a sequence with a smaller image size, FCP will always scale the larger image so that the entire image is displayed.)

This means that your 16:9 material will have black bars (called “letter-boxing”) and the top and bottom of the image.

Since your sequence is already 4:3, you have now created a 4:3 image and could stop there if you want the highest possible image quality.


However, some people object to seeing the black bars in their shot. At this point, you can double-click the image to load it into the viewer and increase the Scale setting. As you scale, you will lose a portion of the image on each size. Another problem is that since all video is bit-mapped (composed of discreet pixels) as soon as the scale amount EXCEEDS 100%, your image will start to get fuzzy, grainy, or blurry. In other words, it starts to look bad.

As long as you don’t scale it too much, you can probably get away with it. The amount you can get away with varies based upon the quality of the source image, the quality of the images before and after it, you personal standards for quality, and other, related factors.

Something similar needs to be done to fit 4:3 material into a 16:9 sequence.

When you add 4:3 material, FCP squeezes it smaller so that the entire image fits into the frame, which adds black bars to the sides (called “pillar-boxing”). You can get the 4:3 image to fit the frame by increasing its scale in Motion, but, as before, you will lose a portion of the image — this time at the top and bottom.

Again, remember that the highest quality you can get from your image is when the scale is set to 100%. Any more will look fuzzy, and anything less means you are not showing all the detail that’s there.

UPDATE – April 2, 2009

George Langley adds:

One neat trick with resizing the 16:9 in a 4:3 timeline back up to 100% is that you can then add a pan that wasn’t in the original footage. (I guess technically is really a tracking shot!)

Just set some keyframes and adjust their horizontal X locations as desired. You can go from one edge of the image to the other, or middle out, whatever. Adds some interest to the shot, as well as getting everything in that the videographer had in their original composition.

(Guess a 4:3 in a 16:9 would subsequently allow you to add a tilt!)

Larry replies: Thanks for sharing this tip. This technique is the low-cost way of doing a pan-and-scan on your video.

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