How to Stream Your Media Files

Let's assume that you have decided to create a video and make it available to your students and others through streaming media on the Web. This is a quick overview of the steps you would need to take:

1. Create a video with picture and sound optimized for the Web. It is recommended that you keep your scenes simple, curtail unnecessary movement by the actors, and put the camera on a tripod. (Complicated backgrounds and motion defeat the compression process, creating larger files.) For sound, use top quality microphones and give one to each person.
2. Edit your sound and video using programs like Adobe® Premiere® (for video and sound) and Sound Forge® (for sound).
3. Decide which format to use. RealNetworks® media (RealAudio® and RealVideo®), Microsoft® Windows Media™, and Apple® QuickTime™ are the most common formats. Your choice may be dictated by which formats are available on the server you want to use.
4. Encode your video file. Free encoding programs such as RealEncoder™ and Windows Media™ Encoder are available, or you can buy encoders with more features. UWTV now offers a for-fee digital media encoding service (see the next article "Encoding Services Available From UWTV Production").
5. Transfer the encoded video files to your streaming media server. This server usually is not the same one you use for your HTML Web pages.
6. From your HTML Web pages, link to your video in its location on the media server.

You can also try the tutorials from Streaming Media World.

Squeezing Media Onto the Web

Several methods are used to squeeze media files for use on the Internet:

• Video files are displayed in a much smaller area at a lower frames per second rate than for television, which displays a 640 by 480 pixel image at about 30 frames per second. (For example, a streaming video file encoded for viewing over 28.8 Kbps modems might be reduced to 160 by 120 pixels at 10 frames per second.)
• For video, sophisticated compression algorithms analyze data within each frame and across many frames to mathematically represent the video in the smallest amount of data possible.
• For audio, sampling rates are reduced, compression algorithms applied, and data for sounds outside of human hearing thrown away.

The process of compressing the files for use on a streaming server is called "encoding." A file is encoded for a specific expected transmission rate. The slower the expected rate, the more the file must be compressed and the greater the loss of quality.

It is common to encode a file at several different rates so that when people visit the page, they can choose the rate that works best for them. Some software, like SureStream™ from RealNetworks, can combine several levels of compression in a single file, leaving it to the player program to pick the best one.

No Faster Than the Slowest Link

• The speed of the media server
• How heavily the server is loaded with other connections
• Congestion on the Internet
• The capabilities of the Internet Service Provider
• How fast the modem is (28.8 Kbps, 56 Kbps, etc.)
• How fast the computer is (166 MHz, 400 MHz, etc.)

The trick is to encode your material at a fast enough rate to take full advantage of the speed of the viewer's connection without over-compressing it (thus throwing away information) or under-compressing it (providing too much information for their computer and player to keep up with).