Understanding Video

WEB SITE VIDEO FORMATS

Any video on your computer or web site is going to be in a digital or 'file' format. Digital video is electronic files - 1's and 0's. CD's and mp3's are digital forms of audio.

Digital video comes in several file formats and within each format there can be many codec 's (for COmpression/DECompression). Some formats require special streaming software on a server to play on a web site and others don't.

Progressive downloading is where the file starts to download, then begins playing as the rest of the file downloads. This prevents the user from having to wait until the whole file downloads before being able to view it.

While progressive downloading is often called streaming, true video streaming determines the bandwidth that the viewer can receive at and sends the stream at that rate. Some can even continuously monitor the rate and reroute the stream or change the rate as the Internet slows down or speeds up.

VIDEO FORMATS

Videos are inherently large files, so there are many methods of compressing the video. It starts with different file formats and within many there are various Codec's.

Each format has an associated file extension, such as .avi, .mov, .wmv, etc.

NOTE: To be able to see the file extensions on your Windows computers go to the Control Panel, Appearance and Personalization if not using Classic View, click on Folder Options, click on the View tab and uncheck "Hide extensions for known file types"

Proprietary formats include .avi, which is pretty Windows-centric, and .mov, which is Apple's version. Generic formats include the different versions of .mpg files.

.mpg includes MPEG-1, MPEG-2 and MPEG-4 Codec's. DVD's and TIVO use MPEG-2 (a DVD file is actually labelled a .VOB file). MP3 is a Codec for audio files.

AVI files have many associated Codec's that you can use, but the person on the other end has to have the same Codec on their machine.

DV-AVI is the format usually associated with digital video cameras. These files can be HUGE... about 200MB of hard drive space per minute.

DivX is the newest kid on the block, using a great Codec. Some of the newer home DVD players are including Divx compatibility, but it's mostly used for large movie files, not streaming.

NTSC is a television standard (PAL in Europe). If a video is to be played on a TV rather than a computer monitor it can be an MPEG file (like DVD) but it must use the NTSC standard.
 

INTERNET MEDIA FILE FORMATS

As mentioned earlier, video on the Internet is compressed using a Codec to compress the file and let it download or stream faster.

When a video file is sent from a web site, the computer on the other end has to have compatible software to play it, either a plug-in installed in the web browser or a separate player.

There are two ways that video is streamed on the web. The main way that Internet video is streamed is called progressive downloading, which can be done from any web server, like the one where your site is hosted. The other way involves special server software.

Progressive downloading is where the file starts to download, then begins playing as the rest of the file downloads. This prevents the user from having to wait until the whole file downloads before being able to view it.

Some formats can use special streaming software on a server to enhance streaming ability. While progressive downloading is often called streaming, true streaming software determines the bandwidth that the viewer can receive at and sends the stream at that rate. Some can even continuously monitor the rate and reroute the stream or change the rate as the Internet connection slows down or speeds up.

Up until recently, the best format for video online is Adobe (Macromedia) Flash.

Flash's advantage is that it's interactive. You can paste text in what are known as “callouts” on top of the video, have it pause until a button is clicked, add links, etc. with the right editor. It's very versitile.

There are two types of Flash movie files. The file extension .swf is for Shockwave Flash. It is used for shorter (16,000 frame limit) lower motion videos and animations.

Browsers with newer Flash plug-ins support using the .flv (Flash Video) format which will stream longer and full motion videos from a regular website - you don't need a special streaming server but you do need a Flash Player – it won't play in either Windows Media Player or Apple QuickTime.

NOTE: To play .flv files on our computer we use the free VideoLAN Player. It can play ANY video including QuickTime and RealMedia, allowing us to uninstall those players and their associated software updates.

The Flash plug-in is installed on about 98% of browsers and is the most widely used of the online video formats, but is not suitable for downloading.

[Editor's Note] As of this writing there's a sort of web video format war going on. Adobe has been dominant with it's Flash format. Microsoft has come out with Silverlight to compete with Flash. Apple's iPhone doesn't play Flash and neither does the iPad (although it will play YouTube videos).

Apple has kind of forced everyone to come up with .m4v videos for mobile devices, now it's upped the ante by not being compatible with Flash on it's larger iPad which can be used to surf the web. Who knows what Steve Jobs has in mind for the future?

Right now the new video format of choice is mp4 (H.264 video Codec, AAC audio)

One possible solution is HTML5, an updated version of HTML that's in the works and will allow videos to be played on web pages without a Flash, Silverlight, or QuickTime browser plug-in.

Windows Media and Apple QuickTime are, in my opinion, only suitable for downloadable videos, not progressive downloads or streaming, which requires server software.

Formats for cell and smartphones are usually .mp4, .m4v and .3gp

I know it sounds confusing, but to simplify matters - I usually use high-quality AVI or MPEG-2 to capture and edit video and save that as a “master” on my hard drive. I then convert it to .flv to stream on the web and, if necessary, convert it to .wmv to make it available for downloads.