We’ve done a lot of studies and tests on… a mouse, … it’s not only easier to use but more efficient.
Steve Jobs
Steve Jobs found that the most efficient way to move a pointer around on a screen is with a mouse. Taking that same approach has the videoconferencing world searching for more efficient ways to move pixels. So what’s the latest state of the art in compression for commercial, off-the-shelf VC tech?
At this point you may be saying, “but Dave, what difference does compression make, anyway?” Fact is, people like to record and playback unlimited still or motion pictures, which create huge files requiring a massive amount of storage and network capacity. Problem is, capacity is limited. This process is the equivalent of stuffing 100lbs of flour into a 1 pound sack.
The tech: usually 30 pictures per second are captured and compressed so that they make up a tiny fraction of the uncompressed version. The encode method, in short, involves creating a group of pictures (GOP) from a single frame, usually making each frame up from the few pictures before and after the full resolution frame. If there are not many changes in a scene over the GOP, most of the information is thrown away. Decode recreates what appears to be an identical amount of resolution from the shorthand frame info it gets from the compressed stream. The latest in wide use? H.264, AKA MPEG4 Part 10, AKA AVC.
How good is today’s compression? Uncompressed HD = 1Gb/s. If you use H.264, Baseline profile compressed HD = 1Mb/s. That, ladies and gentlemen, is 1/1000 of the original!
Even more interesting: H.264 is a whole family of codecs. The best and highest quality are allowed for the in the high-complexity profiles and levels. Tradeoff is that you will need more advanced hardware to encode and decode.
Conclusion: if you are a videoconferencing manufacturer, you can go with Baseline profile, (used on iPods), Main profile (iPads) or you can spend the extra R&D and the powerful hardware you will need to put these High Profile capabilities into your codecs (Blue Ray, MacBooks, NVIDIA ION and PureVideo HD). I’m aware of one VC manufacturer at this point that has implemented H.264 high profile in all of their room and presence systems: Polycom. Most others use Baseline Profile.
What’s the big deal? High Profile cuts the volume of your data stream by as much as 50%. For your network engineer and your internet connections, that means twice as many people or half the load through your infrastructure. Which means adding more people or putting network expansion off.
The math is simple:
- New video deployments typically start with network evaluations. End result is usually upgrades to increase bandwidth and remove bottlenecks. But with High Profile, HD calls that required over 1 megabit per second using Baseline Profile are now supported at just 512 kilobits per second with High Profile. Standard Definition calls that required a minimum of 256 kilobits per second now require as little as 128 kilobits per second. Polycom has included this technology in even basic codecs, allowing small rooms in on this skinny bandwidth bonanza.
- High Profile changes bandwidth requirements for connecting conferencing servers to the IP network. Conferencing servers are the core of the visual communication network, and demand high bandwidth connections. For example, if the conferencing server supports 80 HD calls at 1 megabit per second each, it has to be connected to the part of the IP network that can carry 80 megabits per second. High Profile? Similar conferencing server delivers equivalent quality and scale over a link with just 40 megabits per second.
- Video Border Proxies (VBPs) are the gates to the corporate video network and their throughput is often limited, killing high quality visual communication from off site. With High Profile VC codecs, the existing VBPs in the organization can approximately double their capacity. For example, a firewall transversal unit like the Polycom VBP 6400 E with 85 megabits per second throughput that supports 85 Baseline Profile HD video calls can easily support 170 High Profile HD calls.
All things being equal, the addition of High Profile is a gift for everyone from network engineer to corporate exec. Execs get their VC calls in beautiful high definition, and engineers are much better able to balance the load and carry the traffic. ROI? Don’t get me started!
If you are a glutton for punishment, you can find all the details and intricacies of H.264 profiles and levels here: RFC 4281 and here: http://en.wikipedia.org/wiki/H.264/MPEG-4_AVC