Scalable Portrait Video for Mobile Video Conferencing

Wireless networks have been rapidly developing in recent years. GPRS and CDMA 1X for wide areas, and 802.11 and Bluetooth for local areas have already emerged. Broadband wireless networks urgently call for rich contents for consumers. Among various possible applications, video conferencing is one of the most promising for mobile devices on wireless networks. This paper describes the generation, coding and transmission of an effective video form, scalable portrait video for mobile video conferencing. As an expansion to bi-level video, portrait video is composed of more gray levels, and therefore possesses higher visual quality while it maintains a low bit rate and low computational costs. Portrait video is a scalable video in that each video with a higher level always contains all the information of the video with a lower level. The bandwidths of 2-4 level portrait videos fit into the bandwidth range of 20-40 Kbps that GPRS and CDMA 1X can stably provide; therefore, portrait video is very promising for video broadcast and communication on 2.5G wireless networks. With portrait video technology, we are the first to enable two-way video conferencing on Pocket PCs and Handheld PCs.