James Slocum


A random collection of thoughts on a variety of topics

“A busy month, a shiny new product!”


This has been a hectic month at work! We are releasing several new products and unveiling them at NAB on April 8th. One of the products, the AdCaster is near and dear to my heart! I have been working on this for the last 3 months. My part was to create the C library to handle all SCTE-30 transactions.

So you might be wondering, what does this product do? Well it allows local broadcasters to inject (splice) local advertisements over the top of national advertisements. Have you ever been watching a cable channel like Comedy Central, and it goes to commercial and you see a split second of one ad, then it jumps to another ad? That was a local ad splice done by the local cable provider. This is how local businesses can get their commercials on channels like Fox or NBC. Of course you will only notice it when the splice point is slightly off, otherwise it is completely seamless.

So how does it all work? Actually that is the cool part (in my opinion). The national feed carries embedded markers in the multiplex (MPEG-2 transport stream). Those embedded markers are defined by SCTE-35.


A splicer is listening for those embedded messages and when it finds one it sends a connected ad server (the AdCaster) a message over SCTE-30 that it is coming up on an ad that can be replaced. The AdCaster responds and begins sending the new advertisement video to replace the national advertisement feed.


As long as the SCTE-35 markers are correct, and the two server are time-synced the downstream user should never even know a replacement was made. When the ad is complete the splicer returns to the national feed and the AdCaster logs a successful transaction.

Even though it was a scramble to get this ready for the 8th, I feel that we really have a great product here. We are still making tweaks and bug fixes to the ad delivery code and such but we have put our product through its paces and it’s ready for a production environment!

If you find yourself at NAB this year, please stop by the TelVue booth and check out a demo of the AdCaster in action.

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