Encoding Flash Video
Tom Green
Scott Fegette
Adobe
Table of Contents
The genesis for this article was a conversation between the two of us at TODCON 8 in May 2006. Both of us are spending a lot of our time exploring the subject of the uses, abuses, and potential for Flash video. Though we move in different circles, a major intersection point of our careers is the number of conversations we have and e-mail messages we receive that start with, “I can’t seem to get this Flash video stuff working.” When we compared notes at TODCON, we realized the root of most problems is not the technology of Flash video, but its creation and deployment. More specifically, there seems to be unfamiliarity with the intimate relationship between data rates and bandwidth when the Flash video (FLV) file is created.
In this article, we will discuss this relationship and strip away some of the mystery surrounding it. No matter how you approach the subject, you have to understand that you really aren’t dealing with video. What you are doing is managing a stream of audio and video data into Flash Player.
In many respects, you’re the manager of a river dam. If the floodgates are at the proper setting, the water flows out of the dam and stays within the riverbanks below the dam. An improper floodgate setting releases more water than the riverbanks can contain, and the town downstream gets flooded.
When it comes to video, if the floodgates are wide open the video plays and stops—a torrent of video and audio data is overwhelming Flash Player. The player buffers the data and then releases it, which is why the video stops and starts. Most often, this means the FLV file was created using an overly large data rate. As one of us is fond of saying, “Set the data rate too high and what you are attempting to do is this: Push a watermelon through a worm.”
Another common misconception is that you need to write ActionScript code to control Flash video playback. This is not exactly correct. The ActionScript code you write controls the data stream. The play() and pause() methods of the NetStream class turn the stream on and off. The methods don’t turn the video on and off. This is an important concept to grasp when you approach Flash video.
Requirements
To complete this article, you will need the following software:
Flash Professional CS3 with Flash CS3 Video Encoder
Prerequisite knowledge:
General knowledge of Flash and video.
About the authors
Tom Green is a professor of interactive multimedia at the Humber Institute of Technology and Advanced Learning in Toronto, Ontario. He is the author of several best-selling books in the area of Flash and Flash technologies. His latest book is Foundation Flash CS4 for Designers, coauthored with David Stiller, and he updated Foundation Flash CS3 Video with Adam Thomas. Tom has completed DVD videos for Lynda.com and Adobe Systems, and is a partner at Community MX and a regular contributor to Digital-Web.com and Layersmagazine.com. He is also an active member of the Adobe Community Experts Group, speaking at conferences and seminars around the world and contributing regularly to the Adobe Developer Connection in the areas of Flash authoring and video technologies.
Scott Fegette is the Technical Product Manager for Dreamweaver at Adobe - focusing on web standards, community outreach and developer relations. Alongside speaking across the globe on web development and design, video production and online communities, Scott's also a professional musician and independent photographer in his off-hours.
