11
Video and Audio Coding for Mobile Applications
11.1 Introduction
Increased bandwidth for Third Generation (3G) communication not only expands the capacity to support more users, but also makes it possible for network providers to offer new services with higher bit rates for multimedia applications. With increased bit rates and programmable DSPs, several new types of applications are possible for mobile devices, that include audio and video content. No longer will there be a limited 8–13 kbps, suitable only for compressed speech. At higher bit rates, the same phone's speakers and DSP with different software can be used as a digital radio. 3G cellular standards will support bit rates up to 384 kbps outdoors and up to 2 Mbps indoors. Other new higher-rate indoor wireless technologies, such as Bluetooth (802.15), WLAN (802.11), and ultra wideband, will also require low-power solutions. With low-power DSPs available to execute 100s of MIPS, it will be possible to decode compressed video, as well as graphics and images, along with audio or speech. In addition to being used for spoken communication, mobile devices may become multifunctional multimedia terminals.
Even the higher 3G bit rates would not be sufficient for video and audio, without efficient compression technology. For instance, raw 24-bit color video at 30 fps and (640 × 480) pixels per frame requires 221 Mbps. Stereo CD with two 16-bit samples at 44.1 kHz requires 1.41 Mbps [1]. State-of-the-art ...
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