Applied Technology: StreamOn Smooth Spots

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Smooth Spots

To address ad insertion timing and other streaming challenges, StreamOn provides broadcasters with a dedicated piece of hardware called a StreamOn Appliance. This equipment is passively cooled, has no hard drive or fans (common failure points on computers) and runs a flavor of Unix built for long-term robustness. Using a StreamOn Appliance rather than a software encoder on a Windows machine ensures that the encoder does not have to compete with other system processes such as Anti-Virus software that can cause periodic CPU spikes and create latency.

The StreamOn Appliance runs a chain of processes designed to make ad insertion as smooth as possible. We call this our Smooth Spots solution. The chain of processes work as follows:

1) Rather than having one big program to deal with metadata and encoding, the appliance runs a series of separate processes to handle specific tasks. The first task for handling metadata is to insert a timestamp into the audio feed. The moment that a signal from the automation system arrives we produce a floating point Unix timestamp with microsecond accuracy (ie. 1372440050.123456) and inject that value directly into the audio feed.

2) The system then proceeds to parse the automation data to determine the type of content that just began playing as well as artist and title information. We do this after injecting the timestamp into the feed rather than before as the parsing process can sometimes take 100-300 milliseconds and we do not want that to delay the ad insertion cues. The content type and artist/title information are then mapped to the timestamp.

The ONdemand player shows separated events that the listener can go back and re-play, made possible by the Smooth Spots algorithm.

The ONdemand player shows separated events that the listener can go back and re-play, made possible by the Smooth Spots algorithm.

3) Finally, the timestamped audio gets fed into our patent-pending Transition Detection algorithm. This algorithm scans the PCM audio within a 2-second window around the timestamp and runs mathematical calculations on the audio waveform to search for perceived transition points in the audio. The metadata is then moved to the appropriate location in the audio and ad insertion cues are inserted if necessary. Though not perfect, this algorithm currently has an 87 percent success rate for identifying commercial transition points within a 2-second window of audio. For stations that run modern automation systems, the scanning window can be decreased from 2 seconds to 500 milliseconds for even better results.

4) Audio is then encoded and sent to our servers which work with the Adswizz targeted advertising platform. The Adswizz server reads the inserted ad cues and uses an intelligent buffering system so that if a 2-minute stop set is replaced with 2:10 of content, a buffer is built up and the listener gets moved 10 seconds further behind the live broadcast. This takes away the need to map the exact durations of the original and replaced ads and ensures that when the stop set ends, no content is missed. If over time the listener falls more than 30 seconds behind, the server simply skips a 30 second spot to move the listener closer to the live broadcast.


Ad insertion timing is an extremely complicated problem, but it is a problem that listeners care about and is worthy of focused attention. Our Smooth Spots solution combines dedicated hardware with software algorithms that we are continually improving to address this crucial problem. You can hear this solution in action on our demo page at

Snook is chief technology officer of StreamOn, Edmonton, AB.

StreamOn is an Internet Radio solutions provider, created by the OK Radio Group providing radio broadcasters with tools, technology and strategies for growing online audiences and generating meaningful revenue on social media.

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