Video Telephony (Part I)

We live in a time when ‘to skype’ is a verb and our lucky friends with iPhones (versions after iPhone 4) have the choice of using ‘Facetime’ to communicate; we are in a happy place for sure but how can we get happy-ER?

We live in a time when ‘to skype’ is a verb and our lucky friends with iPhones (versions after iPhone 4) have the choice of using ‘Facetime’ to communicate; we are in a happy place for sure but how can we get happy-ER? Given the fact that Microsoft is buying Skype for billions of dollars, it looks like there’s a lot more ahead. Let’s talk videophones… 

The reason there were no video telephones twenty years ago is due to obstacles such as expensive hardware, non-robust networks and compression inadequacies (in fact video telephony has been around since the 90s but not widespread).

Now that those obstacles are out of the way-standardization and interoperability are forces to reckon with.

Think of this, you cannot use Facetime on your iPhone to communicate with your friend using a Blackberry (for example); the lack of interoperability is a hurdle when video communication comes into play.

Skype uses a proprietary video-compression system-and the same goes for Apple; even if you can add a Skype app on your iPhone, the different systems cannot talk to each other. Companies (Microsoft, HP, etc.) that manufacture communications equipment are trying to create an alliance; the plan is to work with standards organizations, companies and government regulators until the disparate technologies evolve into products that can seamlessly communicate.

But this is not all, there is going to have to be an added ability to talk to a small group of people at the same time-similar to three-way calling; today some applications enable this service but the strain on video-telephony systems creates unacceptable delays.  

Now, one might say, what is so hard about getting a microphone, camera, speaker and monitor screen to work flawlessly across a network? Well, first of all signals captured by microphones and cameras contain more information than can be sent across the networks we have now (wired and wireless)-and more than is necessary for an adequate experience (redundancy).

One way to tackle this is by data compression; an encoder (microprocessor usually) compresses the signal by reducing the number of bits that represent the video and audio data to be sent over the connection-the signal is reassembled by the decoder at the receiver but a lot of data is lost in the compression process as today’s networks don’t have enough throughput to send all the data created by the sender.

For example, one form of high-definition (HD) video has a resolution of 1280 by 720 pixels at a rate of 60 frames per second; uncompressed, that flows at 660Mbps! Even if the resolution and frame rate were cut in half (reducing the data flow to 165Mbps, today’s typical broadband networks operate at a tenth of that rate.

No doubt, compression is a must! Algorithms used to encode signals typically reduce the data by a factor of 250 to 100; digital signal-processing hardware is dedicated to this important task.

Article to be continued next Monday. 

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). 

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