July 08, 2010, 11:13 AM — There are hundreds of Internet video formats, but fortunately for you, you can ignore most of them.
It's all too easy to get tangled up in the seemingly endless number of video formats on the Web. Fortunately for all of us, there are only a handful that you're likely to need to view or use.
There are several reasons why there are so darn many of them. Number one on my list is the sheer number of possible displays and the standards that come with them. To take just one example you might think that all standard definition TVs are the same. You'd be wrong.
Even something as simple as frame rate, the number of images per second, comes with four different standards. These are PAL (Phase Alternate Line), which is used in the UK and most of Europe, Asia, and Australia and SECAM (Séquentiel couleur à mémoire) is used in France and Francophone Africa ) both of which require 25 frames per second. Then, there is NTSC (National Television System Committee, which is used in most of the Americas and Japan), which demands 29.97 frames. But at the same time, film is shot at the slower still frame rate of 24 images per second.
On top of that, video displays can also be interlaced or progressive. With interlacing, which is used in ordinary OTA (over the air) U.S. television, the horizontal scan lines of every frame are split into a pair of fields and a broadcast alternative refreshes one set of lines after another. With progressive, all the scan lines are updated every time. The advantage of interlaced is that you can squeeze video into a narrow frequency while with progressive you get a sharper picture with fewer artifacts.
Oh, and did I mention that the number of those horizontal scan lines varies from standard. Your old analog TV in the U.S. displays 480 lines of interfaced video, or 480i. A television of the same vintage in the UK would show the same episode of Rocky and Bullwinkle in 576i.
But enough of that. I'm not even going to touch on resolution, data compression, and all the other things that makes working with video across platforms and devices such a complicated mess. For practical purposes, if you want to do more with them, look to FFmpeg for those of you who are technically minded. If all you want to do though is to translate one common video format to another then what you want is HandBrake.
That said, let's say you want to view videos, what are the formats you're going to need to deal with? Before jumping into those, let me say that while Ogg Theora is very popular with open-source developers, that's about the only audience which is a fan of it.
No, for practical purposes, there are five formats that you want supported on your PC or mobile device. These are:
- AVI (Audio Video Interleave)
- MPG/MPEG (Moving Pictures Expert Group)
- MOV, Apple's QuickTime format
- SWF, Adobe's Shockwave, aka Flash format
- WMF/WMV (Windows Video Format)
There are other formats, such as Real Media's RM/RAM RealVideo and Divx' DIVX formats that have been important, but are now declining in use. Still others, such as Google's newly acquired VP8 format, which may yet become important. If you can view the five most common formats though you'll be able to view over 90% of the videos you're most likely to find on the Web.
Even beneath these common formats there are other layers of complexity. For example, there are multiple multimedia container formats. These define the packaging around the video files and their associated audio files and meta-data. For instance, videos for mobile phones are often found in 3GP containers; ASF (Advanced Systems Format) is often used for WMV, and so on. Lucky for you, you don't have to worry about much of that. You just need to make sure you have the right video player software and you'll be fine.
