Video Telephony (Part II)

Last week, we explored a few reasons why video telephony is still a budding technology; the shortcomings in interconnectivity and data compression were introduced. I received some feedback that the data compression section was too technical; I will devote an article to this important ‘science’ in the near future but back to video telephony... Coupled with improved compression technology, packet-switched networks are rapidly taking over traditional circuit-switched networks-even for telephones-and have thus simplified the compression problem owing to the increased effective bandwidth available to the user to send tolerable quality video images. Today’s market is flooded with portables with relatively cheap flat panel displays, cameras and microphones, with chips fast enough to process audio and video;today’s smartphones have screen resolutions as high as yesterday’s standard definition televisions! As mentioned above, new compression technology-like the MPEG-4 AVC-is available today and yet it is not good enough; being a video-encoding format, it does not cover other aspects of telephony like audio coding. But even in terms of video coding, this technology is limited because if a packet is dropped during transmission, the user is left with a smearedimage or a frozen image (usually aided by software that masks smearing). Another avenue for improvement is multi-person calls; today if one participant has a strained network, everyone on the call suffers the low resolution of the user’s connection (no matter how great their networks are); same goes for people using devices of varying ‘smartness’ such as a high-powered laptop and a low-end phone. It would be great to see different callers at different resolutions rather than the worst one; another plus would be the ability to make the image of one participant larger on your screen than others. VCEG and MPEG are working on interoperability for this issue by creating scalable video coding, SVC; it is an extension of the MPEG-4 AVC standard and is easy for users with the base standard to enhance their gadgets to also support it. Think of SVC as a ‘middle man’-specifying what a bit stream should look like in order to be read by all devices (using the standard) and how the decoder translates that bit stream into images.; this means SVC gives devices option in terms of video quality (resolution, frame rate, etcetera) by allocating a section of the bit stream to the lowest quality options. Two articles cannot adequately present all the obstacles in video telephony like strained network capabilities, battery drain and ambient noise but nevertheless, in a few years, we will be walking down the street having a video phone conversation and it will be oh, so normal…. Author is interested in emerging technologies and their impact on business and society;she is a postgraduate student in Electrical Engineering at the University of Pennsylvania (USA).akintore@gmail.com