You may be aware of of the term Sigma encoding.  It has been around for a number of years. 

It is a tracking signal developed by Nielsen that can be embedded into spots, public service annoucements and video news releases.

Each product is given its own uniquely indentifiable tracking information.

Like closed captioning, this tracking signal is embedded in the vertical interval portion of the video signal. http://tinyurl.com/599o3h

Nielsen has electronic monitoring stations around the country that can detect the encoded data and can thereby accurately report back to producers, advertising agencies and their clients as  to how much airplay their product is receiving.

Now Nielsen has upped its tracking capability by offering an enhanced version of Sigma called SpoTTrac.  http://tinyurl.com/65c2hp

In addition to encoding tracking data into the video signal,  SpoTTrac provides the added capability to encode that data into the audio signal.

That allows for more accurate (i.e. redundant) and robust tracking capabilities.

Video Labs has added SpoTTrac encoding to our capabilities: http://tinyurl.com/5jhjx7

UPDATE as of Feb 2010:  In subsequent discussions with Nielsen tech experts, we have learned that the transistion to digital broadcast has made the former Sigma encoding aspect of video now obsolete. 

In otherwords, the digital transmission is stripping off the vertical interval information where the Sigma encoding was located.

So we are currently in a period where Nielsen tracking is relying almost exclusively on the audio “watermarking.”

We have also learned some more tech details.  

One is that the success of the  audio watermarking is reliant on the audio of a program being on both the left & right tracks.

We’ve also learned that the audio signal must have enough amplitude (volume) and frequency response for the algorithm of the SpoTTrac to  have enough material to work with in deciding where to “hide” the watermark. 

That’s correct — the audio watermark data is blended within the audio spectrum in a variable way so that is can be masked by the existing program sound.

So the converse is true . . . if the sound of the program to be SpoTTrac’d is silent or has been heavily equalized, then the watermarking process will not work.

Pretty sophisticated that algorithm, no?

Contact me dryan@videolabs.net  (301-217-0000 x104) if you are interested in having SpoTTrac added to your spots, PSAs or VNRs.

As always, I welcome your comments below.

Interested in learning more about the challenges of putting captions and subtitling on DVDs?  I invite your to read my blog on that: http://tinyurl.com/5vgp9m

Here’s also a blog about our HD captioning services:  http://tinyurl.com/6bpxje

You may be interested to know that we also provide SX and IMX format duplication as well:  http://tinyurl.com/6rkc38    http://tinyurl.com/5hp4h8

Follow me on Twitter at www.Twitter.com/drmediasolution for short-term deep discounts.