Some pioneer second-screen applications have been deployed over the past year, so we now can find various use cases for content synchronization, from live TV shows to BluRay and soon VOD, for a wide range of interactive features like quizz/votes, branded merchandising, interactive ads and so on (high creativity required here)… To make the connected devices aware of the content, all of these apps use either automatic content recognition (ACR) via fingerprinting or content tagging via audio watermarking, using the tablet’s microphone as the audio capture source. There are some other techniques, more or less identified, that can also be used, we’ll see it later on.