There are a few reasons why you'd want/need to letterbox your videos. However in this article, I present reasons for NOT leterboxing your videos. The two cases in which I feel letterboxing is not desired are as follows:
- You want your HD videos (16:9 aspect) to look like Cinemascope film (2.35:1 aspect). Image 1 below shows an example of this.
- You’ve probably encoded your video for DVD/Blu-ray and tweaked those settings for online video and ended up with a video that has an aspect of 4:3 with the picture inside it with the normal aspect but with letterboxing (black bars on the top and bottom). Image 2 below shows an example of this.
Image1: Video is in 16:9 aspect, but picture is in Cinemascope aspect (2.35:1)
Image 2: Picture is in HD aspect (16:9) but video is in SD aspect (4:3)
Letter boxing
The concept of letterbox was introduced in order to fit film to video or actually your standard (4:3) TV screen. On ExposureRoom, we retain the original dimensions and aspect ratio of your videos, so there is no real need for you to letterbox your video, since there is nothing to try and fit it into. So use this feature to your advantage and make the best of what we offer you.
Crop your Cinemascope (2.35:1) Video.
If the first case above applies to your video (see image 1 above) then I strongly suggest cropping your videos to the desired dimensions using Adobe Premiere Pro CS3, Quicktime Pro, Sorenson Squeeze or other tools. If you’ve gone through the trouble of shooting within the confines of a 2.35:1 frame, and edited your video with black bars on the top and bottom, why not go through one more step to get the most out of this effort by cropping your videos? I’ll explain why in a moment.
HD Videos in HD Aspect
If the second case above applies to your video (see image 2 above) then the issue really is the wrong encoding settings. Your video is really a 16:9 aspect (SD wide or HD) and you should render it as such. Please look at the article titled,
Getting your videos to show in the correct Aspect in our
online help section for how to get the correct aspect for your videos.
Problems with Letterboxing your Videos
There are two reasons you should not letter box videos or actually Not crop your videos (as the case may be). In the first case you're intentionally letterboxing but you're not cropping your video to the actual dimensions, and the issues with this are:
- The video looks a whole lot better without letterboxing.
- The picture quality is not as good as what it would be if you cropped your video instead of simply letterboxing.
The second case has one issue and that is the picture quality is not as good as what it would be if you encoded your video correctly in order to produce a video with the correct dimensions.
Why the Picture Quality suffers
You probably know that the
video bit rate plays a major role in the quality of your video. If you don’t understand this, please read the article title,
Encoding Videos for online Viewing. So what does it mean, when you’re encoding your video at say 3,500kbps? Before I try and explain what it means, let’s establish some points of reference for this discussion. We’ll use a video that has been encoded with dimensions of 1280x720 (16:9 aspect) but with letterboxing (see image 1 above), lets also assume that this video has a frame rate of 30p.
Now when you encode your video at 3,500kbps (kilo bits per second) you’re indirectly saying you’re using 3,500 kilo bits of information to represent 30 frames or images, where each image has a dimension of 1280x720. Some of you have probably figured out where I’m headed with this, but I’ll explain anyway.
If the dimensions if the video were smaller you’d have more bits to represent each frame. In other words, if you crop your wide screen video to the actual size of the picture rather than leave the letterboxing in place, you’d get a video that has dimensions of 1280x544. Each frame is actually smaller and given the same video bit rate you have more bits available to represent each frame and so the picture quality improves a bit.
Image 3: Cinemascope aspect (2.35:1) picture and video. For Cinemascope video, crop the video to the correct dimensions.
The same applies for case 2 above. If your video is encoded with the correct dimensions, the actual frame size is smaller (for the same given width) since the height is smaller and so once again you have more bits to represent each frame.
Image 4: HD Video in HD aspect (16:9). Not letterboxing.
I hope this explanation helps you understand why you should not use letterboxing for your online videos and in particular on ExposureRoom since we retain the dimensions of your video.