Spatiotemporal H.264/AVC Video Adaptation with MPEG‐21

The ubiquitous computing concept has brought a revolution permitting consumers to access multimedia contents anytime and in any multimedia capable device. Streaming rich media contents to small handheld devices like cell phone, PDA is a reality now due to the advancement in mobile data communication networks. To lessen the gap between the concept and reality, media adaptation is receiving attention to make the presence of the identical content in different devices viable. The Universal Multimedia Access (UMA) concept is a way to slam close this gap between consumers and providers by allowing access to multimedia contents from anywhere, anytime, and with any device. Video adaptation is a newly introduced practice for direct manipulation of an encoded bitstream to meet resource constraints without having to encode the video from scratch. For example, spatial adaptation is performed to match the original video to a device's screen resolution or varying network bandwidth by cropping desired frames to an areaof interest from the original bitstream. This chapter describes compressed‐domain patiotemporal adaptation for video contents using MPEG‐21 generic Bitstream Syntax Description (gBSD). In addition, it also covers how this adaptation scheme can be used for online video adaptation in a Peer‐to‐Peer environment.