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Codec holds promise for UHD sound

While the world is moving to UHD TV what is happening on the audio side? Most broadcasters, it is feared, will be content to compromise new UHD services with 5.1 surround, an HD standard.

“Broadcasters seem to have made their choice,” said Clemens Par, CEO, Swissaudec. “Their UHD is 4K, together with HD 5.1 surround. It’s too big a risk to renew already costly infrastructure and further stretch the know-how of daily workflows. UHD audio seems likely to remain a cinema domain.”

Swissaudec, however, has devised an answer.

Its ECMA-407 codec broadcasts UHD audio up to the NHK 22.2 surround format, and is backwards compatible with HD.

“Three UHD audio standards are capable of transmitting NHK 22.2,” explained Par. “MPEG-H, ATSC 3.0, and the Ecma S5 standards family, in particular ECMA-407. Only ECMA-407 is capable of achieving sufficient compression at lowest bitrates to transmit NHK 22.2. MPEG-H by contrast is restricted to 9.1.”

The Swiss-Austrian mathematician claimed ECMA-407 will decode in real time, reduces spatial bitrate by 99 per cent, has a payload of just 2kbps and represents no additional cost for HD broadcasters. “All of this is most important for smartphones and tablet
use,” he added.

ECMA-407 uses inverse coding in the time domain, which is Par’s invention, and shows the lowest spatial bitrates ever achieved. For example, several minutes of NHK 22.2 can be represented by an encapsulated data package of 100 bytes.

ECMA-407 was first implemented by Swissaudec in 2014 in co-operation with a research group at École Polytechnique Fédérale de Lausanne and was tuned by Swissaudec and researchers at McGill University, Montreal.

Other project partners include Ateme, SES Astra, France Télévisions and Merging Technologies.