HIGH DEFINITION VIDEO CONFERENCING (HDVC)
This article introduces the High Definition or HD Video Conferencing, the standards used in HD video conferencing with reference to definition(pixels) and presentation of motion (frames per second), advantages of HD video conferencing, aspect ratio and bandwidth in HD video conferencing and requirements of HD video conferencing.
What is High Definition (HD) Video Conferencing?
The older/some of current video conferencing is referred as SD or Standard Definition Video Conferencing. This is popularly referred to as 480p format has a resolution of 860x 480 and supports up to 30 frames per second of video in a 4:3 aspect ratio . So , when such video conferencing systems are connected to HD displays (supporting 16:9 aspect ratio), they would either introduce two black lines at the two edges to make to 4:3, or adjust the image to entire screen causing reduction of clarity.
With High Definition Video Conferencing systems, two popular formats are supported – 1080p with a resolution of 1920 x 1080 pixels or 720p with a resolution of 1280 x 720
pixels. Both the formats support direct 16:9 aspect ratio and hence making use of the entire screen of a high definition display.
The basic difference between the older SD technology and HD technology is the definition – HD supports a higher resolution (More resolution directly means more information and better quality) and they use a technique called progressive scanning in which every horizontal line of pixels are displayed from top to bottom, one after the other compared to the older interlaced scanning by SD systems which alternates the horizontal lines for display, essentially refreshing the image before it can be displayed) and because of which it is twice as fast as the older SD technology. The presentation of motion which is displayed in terms of frames per second also enables the display of subtle changes in motion with a true 30 frames per second and 60 frames per second support.
High quality always comes with higher bandwidth. So, generally HD systems need a minimum about 1.5 Mbps of bandwidth to display crisp and sharp images. When
compared to an SD system which could display images even at 128 kbps, this is quite high but the quality is far better.