MPEG-4’s Objective Point of View
MPEG-4 can overcome many of the limitations imposed on video when streamed, allowing for a greater depth of information, and has the potential to be used as a true streaming multimedia format.
"Traditional broadcast video uses still images, backgrounds, stock ticker data displays, logos, [and] video and audio. Traditional streaming encodes that as a single stream. Often the text, images, and overlays are illegible," says Ahmad Ouri, vice president and general manager of MP4Net, the Broadcast and Internet Content Delivery group within Philips Electronics. "With MPEG-4, each of those assets can be streamed as separate objects and be rendered, assembled and displayed at the end-user side."
Just like Apple Computer's QuickTime4 (the technology on which the MPEG-4 specification was based), MPEG-4 files can provide much more than just compressed audio and video. Just as you can create "QuickTime Movies" that are multimedia files (with text, images, and so on) without any video or audio inside them, with MPEG-4 you can assemble streamable collections of 2D and 3D graphics, text and executable objects with or without video as part of the mix.
This ability of MPEG-4 to "think outside the frame" allows it to deliver much smaller, more efficient file sizes, even though the actual compression technologies it employs aren't significantly different than those of MPEG-2. Working with objects gives MPEG-4 a whole toolbox of tricks to use when encoding video. By doing things like extracting static backgrounds as individual objects and identifying the foreground and moving objects as individual elements for display and compression, it can maintain much lower digital video file sizes than MPEG-2.
Moreover, working with objects and limiting frame rates to 15fps and under, allows MPEG-4 to leave the wire and be delivered to handheld wireless devices like PDAs and cell phones. MPEG-4's scalability allows it to display, or not display, some of the objects based on the device profile of the receiver. That's not surprising, since MPEG-4 was designed with real-time teleconferencing, not HDTV, in mind.
Back to story