The Video Animal’s Cave

Hiya all, I am back from a long bout of hard work and it is time to finally finish up this series of articles on web video posting.

In previous articles we set you up so that you could de-interlace and compress your video properly. Now it is time to do a bit of embellishment and make a few minor corrections before you give it to the world to look at, cut down, love, hate or just ignore.

To understand sort out the last bit of confusion when compressing video, you need to understand a ferw basics about video size. You will often hear this referred to by video geeks like myself as ‘aspect ratio’.

The common problem that most face with HD video is that it is in a non standard size.

When we talk about the size of a video you will often hear it called “Aspect Ratio”. This is the ratio of width by height of the video. Television is 4:3 and HD is 16:9. In computer based video there is a large amount of variations when it comes to picture size. The ratio is great to define how big the width has to be compared to the hieght, but the computer needs more defined information. This is where pixels come in. For example, television is 640X480… that is there are 640 pixels across the top of the picture, and 480 across the width of the piture… kinda like the square footage of the video image. Most television and YouTube video is 640×480 (notice that the ratio of pixles is exactly 4:3) and HD video is wider (1440×1080… generally… notice once again that the ratio of pixles is 16:9)

If you compress HD straight up it will most likely compress in a 4:3 aspect ratio unless you know what setting to use. This stretches out the people on the screen and makes them all look funny. If you ever watched an old western before the invention of pan and scan or widescreen video formats you know what i mean (i used to think clint eastwood was really tall and thin)

Many compression programs will automatically adjust the video and output in a widescreen format, this is great as long as you are looking at it on your computer. As far as i know, most video hosting sites will still try to cram your video into the standard 4:3 aspect ratio, as HD is still a relatively new format and their programs were designed to handle standard video.

Aspect ratio has another handy use, if you reduce the amount of pixels in a video , yet still remain within the aspect ratio, you can lower the amount of data it takes to put your image on screen. The image will be a bit smaller, and the clarity will be a bit lower, but if you are dealing with a really long and detailed piece of video this can often be the only way to cut down the data. To go back to our ’square footage’ analogy. Making a room in your house that is 16 feet by 9 feet will take a whole lot of material, however, make that same room in minature… perhaps 16 inches by 9 inches and you will use very little material. You won’t be able to see as much detail (or live in it) but the room will still ‘look’ much the same. In video, the easiest way to half the amount of data is to cut the amount of pixels in half… an image that is 640×480 will be half the data size if you compress it as a 320×240 pixel image. You still maintain the aspect ratio, so your subject won’t get distorted, yet you cut the amount of data you need to make the image appear on screen by half. Now that you understand a bit about aspect ratio, it will be easier to mess with it in the setting of your compression software to get the results you want!

To get a widescreen image in to a 640×480 video you need to either manually adjust the image within your editing software, or, apply a filter in the compression software. Personally, i find the filter works best and takes less of your time messing around with settings.

Start by making your HD film within a normal HD timeline. It should allow you to edit in real time ( as long as you have enough ram to keep up!) When you are ready to output the video you need to ‘preserve the aspect ratio using letterboxing.’ THis means adding a black line on the top and bottom of the video so that the image is squished back in to the shape it is supposed to be in.

The easiest way i have discovered to do this so far (and that works flawlessly every time) is using compressor which will be a part of your copy of final cut pro. Although I haven’t used Premier or other video editing software to do this, I am sure they have something that works much the same.

With the segment you want to export open click on File>Export> Using Compressor. This will open up the compressor program and open up the compression viewer so you can see how the video will look. Highlight the video you are exporting under the ‘batch’ tab. The video will now appear in the preview window. If it was a 16×9 video you will notice almost immeadiatly that the image looks distorted. That is because the preview window shows the image in a 4:3 aspect ratio automatically. Correcting the distortion is simple.

First we need to decide which setting we are going to use. For the fishing video I am working on I want it to be really small so I can email it, so I am going to go to the extreme and compress it as small as I can. To do this Iwill output put it as 160X120 .. maintaining the 4:3 aspect ratio, just really tiny. To do this, click under the ‘Setting’ in the ‘batch’ window go to ‘web streaming (quicktime 6 compatible)>mpeg4 100kb streaming.

If you look at your preview window you can see that on one half the screen is the approximate results of the video… and it looks really pixelated. Not to worry. It won’t be nearly as noticeable because the video will be so small on the screen people will not be able to see all the details. (see video example)

Now to letterbox.

In the inspector, click on the ‘Filters’ Tab… the button that appears to be a piece of film covered by a gray square. Check on box beside ‘Letterbox’…tada!!.. oh wait.. nothing has happened.. stupid apple default…

Due to some very silly thinking on the part of the programmers, the default letterbox setting is one no one ever uses! You need to set it yourself… don’t worry. With the ‘Letterbox’ filter highlighted, adjust the ‘output’ to ‘16×9 1.78:1′, and your black bars will appear. Your video is now ready to output. Click the ’submit’ button in the batch window.

You can also add those black bars manually with a filter within the editing software by applying a letterbox filter to the video before you export. For those of you using simpler video software this may be the best solution. Often when you go to export the video it will add these bars automatically for you if (such is the case with Premier) if you export an HD video in a standard format. Finally, Quicktime does include a setting called “preserve aspect ratio using letterbox”, but in my experience it doesn’t always work.

On a final note:

Without going in to to much technical detail, it is important to understand that your image will get funky looking if you stray from the aspect ratio. It will simply distort the image. You might also have noticed that all the presets in our demonstration and indeed, in the software itself always cut the aspect ratio in half, or quarter or eight.. never by a 1/3 or some other division. This is because pixels are square, cutting them in half is easy, the software just splits them. If you cut them in a 1/3 the software has to compensate for the extra bits left all over the screen and do a lot more math. Simply put, you end up with more distortion. The rule of thumb is, when you are messing around with the pixels, always divide them in half, 1/4 ,1/8, 1/16 etcetera. (there are more technical reasons for this, but i want to keep it simple here) This way you avoid any extra distortion. We will talk about this in greater detail at a later time, because pixels really become a problem when you are manipulating text or images within a video.

And now.. A HUGE FISH (click the link…can’t seem to get it to embed today)

The Tarpon Jumpin Video

Good luck everyone!

The Animal