Bandwidth requirements and types of connectivity for video conferencing
¤ Professional Video conferencing can be set up with just 128 Kpbs (Dedicated 1:1 guaranteed) bandwidth.
¤ H.264 technology enables you to make a video call at a higher quality with a lower bandwidth.
¤ You can use a lot of connectivity options to set up a professional video conferencing solution – ISDN, PRI, Leased Lines, Internet Leased Lines, MPLS VPN, IPLC, etc.
Bandwidth requirements for professional Video Conferencing solution:
The brochure of some video conferencing vendors claim to set up a Video Conference call at just 64 Kpbs of dedicated bandwidth. While you may get some video (if you are lucky), there will be nothing professional about it! Even for a lossless medium like circuit switched ISDN lines, you need a minimum of 128 Kbps to get a decent quality video call at 15 frames per second. And you could get even 30 frames per second at a bandwidth of 256 Kbps (This may be possible at a slightly lower rate too) for ISDN lines and video conferencing systems employing H.264 compression at both sides. For IP, the calculation is similar, but since you can expect some packets to drop (Unless it is a point to point dedicated leased line) it is better to consider 256 Kbps per video call (minimum).
What is H.264?
H.264 is an encoding technology used for compressing the video packets while sending and it would be de-compressed at the other end when received. This function is done by the video conferencing codec. One advantage this technology had over the previous versions is its ability to use previously encoded pictures as reference. This works with Video Conferencing as there is generally a large static or non moving background which need not be sent every time. So, this portion is stored as constant and only the changes are encoded and sent either way. So, the result is getting a better quality picture at lower speeds.
Types of connectivity that can be considered for professional Video Conferencing:
Each ISDN line supports 128 Kbps. So, a point to point video conferencing call can be set up with two ISDN lines on either side. Most of the common Video conferencing units support up to 4 ISDN lines to be connected (Mostly used for 1+3 multi-conference). Some Video Conferencing systems support PRI/T1 lines too. Here the bandwidth available is very high.
An internet leased line (MPLS VPN) with a minimum of 256 Kbps guaranteed bandwidth (Upstream and downstream, 1:1 guarantee) should be sufficient per site for a Video conferencing solution. The higher the bandwidth, the better the quality. Most of the common Video conferencing systems support up to 2 Mbps of such IP bandwidth but be sure to set the maximum bandwidth that can be utilized by VC application in the codec – otherwise all 2 Mbps might be used! You can also use point to point connectivity solutions like IPLC (International connections), leased line but these options are costlier and give a better quality of service.
Broadband is a slightly tricky question. We have faster and faster broadband connectivity coming up day by day. The issue with broadband is – while the download speeds are very high, the upload speeds are very slow. While this maybe good for internet, video conferencing work better in lines that have equal up-stream and down-stream bandwidth. Who knows, with advancements and new connectivity (3G etc) every day, professional video conferencing systems might just adapt to them too!
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