So You Want A Video, Huh?
[What is Compression?][Playing the Videos]
A video? On your home page? Yes. Videos have been on the Internet for a while now, and if you don't mind spending a healthy chunk of change for the hardware and software required to make them, they're pretty simple to create.
Video FormatsThere are many different formats of video that will play on one type of computer or another depending on the software the user has installed. But over the Internet, there are three formats that are used almost exclusively. Here are some small, four-second videos of me. Now you get to see what I really look like.
Nice looking guy, huh? Yup. That's me. And you thought I looked like that silly cartoon drawing on the home page.
Note the differences in file size between formats. Forget that. Note the file size at all. There's no doubt about it, people -- these things take up a lot of space. But how are they produced? First off, let's look at how a real video is put together. It'll help later.
Film and Video
Film and motionI have do doubt that all of you have seen a piece of film. A film is put together through one little picture replacing the one before it. As the film strip passes over the light, each frame (the little picture is called a frame) is displayed. The frames roll past fast enough that your eyeballs perceive some sort of motion. The pictures on a film strip do not carry motion. Your eye just perceives the quick passing of static frames as motion. It's a neat little trick that will help us later.
In case you're wondering, 24 frames pass over a film projector's light every second.
VideoAh, video. A big fat cassette tape that carries pictures and sound. And it's not a whole lot more than that. The tape that is used in a video cassette is not all that much different than the tape in a cassette. It's just made to carry sound and video rather than just sound.
It would seem that if film used 24 frames a second, then video would just follow through and do the same. Not so. You see, video is used on television mostly and television uses a 30-frame-per-second speed. So video does, too.
What about those slower video speeds like SLP and LP? Those do run the tape more slowly, but still produce the 30 frames a second. It's just that by running the tape slower, the VCR is asking more and more information to be saved in a smaller and smaller space. This makes for a less pleasing picture. The slower speeds are a trade-off between picture quality and amount of data on a VCR tape. This little ditty of information will also be helpful later.
Digital VideoThe three video files above are all digital video. Each is a different format, but basically they do the same thing. They play back a "video" in digitized form. Just as a scanner will make a digital photocopy of a picture, a video card will make a duplicate of a video movie.
I say it will make a digital copy of a video rather than a film, because film is not in the correct frame rate format; 24 doesn't go into 30 cleanly. In addition, video is already movement in a mechanical format. Video is captured motion played back through electronic transducing of metal particles into color and motion.
Every time one of the 30 frames rolls past, the information saved on the VCR tape is read by a video reader or "head." That head is electrified and the magnetic particles on the tape disrupt the electrical "field" the head is producing. That disruption is displayed to you as a picture. That's as un-technical as I could explain it without resorting to hand puppets.
Now, since the magnetic field is already there, why can't we just send that disrupted signal to a computer rather than another VCR or TV? We can. That's how those three pups above were produced.
The HardwareThe equipment one needs for video capture is quite simple. You'll need something that plays the video -- like a VCR -- and a video capture card of some sort that slides into your computer. In addition, you'll need a fairly strong computer with memory... lots and lots of memory. A big hard drive doesn't hurt either. You hook the VCR's out-ports to the video capture card's in-ports and you're pretty much good to go. I'm sure software will come with the card, and barring any unforeseen problems you should be able to grab video with the best of them.
Cost is a factor, I'm sure. As with anything else, the better you buy, the more you will pay. The more options you want, the more you pay. My video card has the ability to capture a full 30 frames a second in two different formats using a few different types of compressions rations. I paid $600 for the card and the software I wanted.
Video FormatsThere are three basic formats of video used on the Internet today. I am not including the streaming videos that are just starting to come out. I'm talking simple video formats. Here are all three:
- AVI This stands for "Audio/Video Interleaved." It's a video format created by Microsoft that allows video and audio to be saved together. This is the premier video format on the PC because it allows for many different compression schemes and reproduces a good picture. But it also requires a lot of space. The extension for a file in this format is ".avi".
- Quicktime This is Apple computer's MAC-based format for playing movies. Apple has made the format quite popular on the Internet by creating players that allow the format to be run on an IBM computer. The Quicktime format is also popular because of its compression scheme. Files in Quicktime are usually less than half the size of their AVI equivalents, but do lose quality. The extension for a file in this format is ".mov".
- MPEG It's a video format created by the Motion Picture Experts Group, thus the name. The format runs on both MAC and IBM platforms and is valued for its compression rate. A large file can be transferred to MPEG losing little quality while dropping the bit rate a great deal. The extension for a file in the format is ".mpg".
I own IBM computers, so I capture in AVI format. Once I have the video in AVI, I then use two separate pieces of software to change the video from AVI to one of the other two formats. AVI can be turned into MPEG straight away. The encoding process takes around two minutes for every one second of AVI video. Quicktime is a little different story. The entire AVI file must be resaved with a different compression rate, known as "Intel Indeo." Then the AVI can be run through a Quicktime converter. That process is very fast.
What Is This Compression You Keep Talking About?!?!Allow me to explain using two image formats first, GIF and JPEG. GIF format is a WYSIWYG (what you see is what you get) format. The file saves at the same size it displays at. If it's a 10K file size, then it takes up 10K on your hard drive and then must be transported at 10K. Period.
JPEG, on the other hand, is a compressed format. It may display at 10K, but it saves and transfers at only, say, 6K. Pretty slick. The thinking is that the phone lines aren't getting any bigger, so let's make the files smaller.
Videos work the same way. AVI does use a compression rate, but not as aggressive a rate as a Quicktime video. You can see that above where the Quicktime film is less than half the size of the AVI. However, the AVI is a far better quality image. So where's the happy medium? I don't know. Which is better, quality or transfer rate? That's up to you.
For an idea of compression and size differences, see my Digital Video: Relative Size page.
It's my opinion that the future of TV and video is all in the compression rate. What if you could purchase a TV show to watch whenever you wanted? For instance, you want to watch Seinfeld right now. Well, it may not be on right now. But what if you could put your credit card into a computer and order the show over the Internet from NBC? Would you? I would. I'd even pay a little more to get a copy without commercials.
At today's compression rates, a half hour show would take up in excess of 75 megabytes. That's where the future is -- in compressing a show so it downloads in a minute. It's coming -- I can feel it in my bad knee.
Playing the VideosIf you attempted to play the three videos above and couldn't, it's not because I don't like you, it's because you don't have the correct video player. And you should have them -- they're free. Some may have even come with your computer. But if not, here are a few links you can use to get in on the video fun:
One more thing...Would like me to make you a video? HTML Goodies has just opened a Video Service. Come by, check the prices, and maybe get your own movies on the Internet.
[What is Compression?][Playing the Videos]