Jack Kontney /
05.06.2011 10:25 AM
Fraunhofer MPEG Surround provides low-bandwidth 5.1 surround

Inventor of the MP3 technology and co-developer of Advanced Audio Coding (AAC), the Fraunhofer Audio & Multimedia division is continuously developing next-generation technologies for future digital media. While the Fraunhofer name is little-known to the public, its technologies are the driving audio force behind more than 1 billion consumer devices worldwide. The company announced several new advances and partnerships at the 2011 NAB Show.

In a demonstration of the show floor, the German codec developer demonstrated its MPEG Surround technology against a full-bandwidth, unprocessed version of the same audio. While trade show floor conditions are hardly conducive to critical listening, this reporter was stunned to find no easily discernible difference between the two program sources. What makes this exciting for the broadcast industry is that this technology enables delivery of full 5.1 surround sound at stereo bit rates as low as 64kb/s (fully compatible with stereo decoders), preserving precious bandwidth while delivering an immersive surround experience for consumers.

“You have to understand that audio coding is a mixture of both signal-processing science and psychological perception,” said Robert Bleidt, general manager of Fraunhofer USA’s audio and multimedia division. “You have to be both a hard scientist and a social scientist when you develop audio codecs. In our organization, we start with an idea and develop the science behind it, but it always comes down to listening tests, double-blind tests with panels of expert listeners. This has been an integral part of our codec development process for over 20 years.”

Among the company’s announcements at the show was a partnership with Orban to make MPEG Surround and HE-AAC audio formats available in Orban’s professional Opticode-PC streaming encoders. This integration will enable Internet broadcasters and music services to provide a full surround experience at the same bit rates normally required for stereo transmission.

Fraunhofer is also active in the area of loudness control.

“With the upcoming implementation of the CALM Act, it’s important that the broadcast metadata used for ATSC makes it through the entire signal chain to the consumer, especially in cable, satellite and IPTV transmission, where codecs other than the AC-3 used in ATSC might be used. To address that issue, Fraunhofer AAC Metadata Technology has been developed. This solution permits all standard ATSC metadata, such as dialogue normalization, dynamic range control and downmix coefficients, to be translated in real time to their AAC equivalents,” Bleidt said.

“This software enables the operator to convert AC-3 metadata to equivalent AAC metadata for those cases where you have an incoming ATSC signal that might be converted to other formats such as H.264 and AAC before going to the consumer,” Bleidt said. “We have the software available now and are presenting it to manufacturers who build headend equipment to allow metadata to be transmitted all the way through to consumer receivers.”

Fraunhofer also announced a rare consumer product from the company, a VST plug-in marketed by Sonnox. The Fraunhofer Pro-Codec plug-in enables DAW users to use the AAC and MP3 families of codecs directly within their favorite audio editing software. The plug-in works with Pro Tools, Audition, Acid, Logic, Cubase and WaveLab, and enables files to be saved in both compressed and lossless formats. It also allows on-the-fly monitoring of codec output and enables simultaneous encoding to multiple formats and bit rates.

Bleidt noted that Fraunhofer’s attention to quality and involvement in international standards committees necessitates long lead times between the initial concept for a codec technology and its appearance before the public.

“Our products are always in an MPEG standard and/or an ISO standard,” he said. “Other companies might have their proprietary technology written into applications standards, like ATSC writing Dolby AC-2 technology into American TV broadcasting. But in terms of an international standard, we’re really the only company that does that for audio coding. It means that we may spend a little longer on standardization, but also means that our technologies have been very carefully scrutinized to become a published international standard. It may take five to seven years for an idea to reach the marketplace. That takes quite a bit of patience and discipline, but the results are well worth it.”



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