Fraunhofer Audio Blog

Sonamic TimeScaling Delivers Seamless Switching Between Broadcasts And Web Streams In Car Radios

March 20, 2018 | Category: Automotive, Good to know, Products & Technologies, Video

Imagine a car radio that keeps on playing your favorite local radio station — without interruption — when you drive out of the station’s broadcast range. That’s the promise of Hybrid Radio, and Fraunhofer’s Sonamic TimeScaling technology is critical to its success.

A Hybrid Radio switches from broadcast reception to a station’s web stream when the broadcast signal weakens at the fringes of a station’s coverage area. Fraunhofer’s Sonamic TimeScaling algorithm makes the switch seamless and uninterrupted.

Without Fraunhofer’s solution, web-stream playback could be delayed by more than 20 seconds, leaving an irritating gap between the time that the broadcast signal drops out and streaming begins. Or a snippet of music might be reproduced twice during the broadcast-to-streaming transition, almost like a scratch on a vinyl record causing a turntable’s stylus to jump back.

In the radio, the TimeScaling algorithm synchronizes a station’s broadcast and web stream so your favorite songs play without interruption during a long drive. If you’re a sports fan, you won’t miss the tie-breaking goal. And distance won’t come between you and your favorite news commentator or disc jockey.

Here’s how TimeScaling performs its magic:

The radio recognizes in advance that the broadcast signal is fading and will soon be lost. The radio then begins connecting to the station’s web server via the vehicle’s embedded cellular modem or via a smart phone connected to the car stereo system. The radio estimates the time delay between the station’s web stream and broadcast signal, then delays broadcast-signal playback in a way that is inaudible to the listener. Soon, the two streams are synchronized, and the stereo system transitions to the web stream so the music doesn’t skip a beat. The audio signal is not changed in any perceptible way, and volume levels are adjusted automatically, making for a smooth transition.

TimeScaling also works in reverse. The radio switches seamlessly from streaming to broadcast reception when it recognizes that the broadcast signal is strong enough to deliver robust reception. That keeps the amount of mobile data used for streaming to a minimum.

Hybrid Radio with TimeScaling could also bring other benefits to motorists. A radio’s station presets, for example, could recall a station even if the car is outside a station’s coverage area.

Hybrid Radio and Sonamic TimeScaling are compatible with analog FM stations as well as with digital radio stations that use one of a variety of digital transmission standards, including Digital Radio Mondiale (DRM), Digital Audio Broadcasting (DAB and DAB+), and HD Radio.

What’s more, Hybrid Radio with TimeScaling is already on the road, having arrived in Europe in the Audi A8 in fall 2017. Other automotive manufacturers also plan to integrate the technologies into vehicles sold in Europe, and launches outside Europe are under consideration, potentially bringing the benefits of Hybrid Radio and Fraunhofer’s technology to a global audience.

Further information: www.fraunhofer-sonamic.com


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