What is High Definition (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 860 x 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.

Requirements for a High Definition Video Conferencing:

For an effective high definition video conference session to happen, the video conferencing units at both ends (or all ends) must be HD enabled. Well, there is not a huge price difference between a SD video conferencing and a HD video conferencing unit, so this may not be an issue. Also, the camera should be HD enabled. A minimum bandwidth of 1.5 Mbps is required over IP or PRI for effective HD video conferencing. The display unit(Like LCD, DLP, Plasma displays) should also support HD display and should have an aspect ratio of 16:9. These devices could be bigger in size (like 50″ diagonal) and still deliver a good clarity when compared to SD monitors which need to be less than 27″ diagonal and have a 4:3 aspect ratio for effective quality. A wide band audio support would also enhance the experience. It is suggested that even the document cameras (which help transmit the contents of a paper/brochure to the other side) is high definition enabled. It always helps to have set strict QoS parameters in your network for prioritising video traffic. The high definition display units should have HD connectors like DVI-I or YPrPb in order to connect to those ports of the video conference units. If an MCU (Multi Conference Unit) is used, even that needs to be HD enabled along with all the video conference units.On a related note, refer the following article for the bandwidth requirements and types of connectivity for normal video conferencing systems.

The advantages are obvious: Better quality video, ability to see crisp and clear images including eyeball movements, facial expressions etc, support for 16:9 resolution and bigger and effective display units, and the ability to view excel sheets, ppt slides and images, display boards etc. with a very high clarity.

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