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Modernizing Audio Codec Industry Standards For Enhanced Power Savings And Performance

Updating a specification’s reference software and basic operators for modern DSP architectures.

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Mobile phones have become a necessity, and we all use them to talk, play, communicate, and manage many aspects of our lives. While you may have an iPhone, your friends might have an Android phone  from one of several vendors. They all look and feel different, yet you can seamlessly talk with your friends. How is that possible? While they are different in some ways, they are similar in many others. This commonality enables one vendor’s phone to talk with a phone from another vendor. Standards make this possible, and these common technologies are identified and standardized by organizations such as 3GPP for wireless and ITU for wired communications. Almost every semiconductor company as well as mobile operators and research organizations from all over the world participate in these standards bodies that strive hard to bring consumers the benefits of the latest technologies in speech, audio, and video compression as well as modem and RF technologies. You may have heard of the latest 5G phones and how you can download movies in a jiffy. Well, 5G was standardized by 3GPP.

3GPP releases reference specifications that phone vendors must comply with so that their implementations are interoperable. Reference specifications are often released as software that semiconductor companies then implement on their system on chips (SoCs). In turn, the reference software is built on foundational operators called basic operators (BASOPs). It is the combination of reference software and the BASOPs that guarantees interoperability. The last version of BASOPs in the 2005 timeframe, called STL2005, was built on an earlier generation of processors or specialized processors called DSPs. Since then, modern DSPs have become prevalent, with several architectural improvements like single instruction multiple data (SIMD) and very long instruction word (VLIW) that allow many operations to be executed simultaneously in one cycle. However, the earlier STL2005 BASOPs did not leverage these benefits.

Cadence proposed a change to the BASOPs to leverage the benefits of modern DSP architectures and worked over a period of about three years with several participating members of 3GPP, which works by consensus. Not only did Cadence propose and contribute the detailed changes to the BASOPs, but also updated the latest EVS (Enhanced Voice Services) codec reference and showed the benefits of the updated BASOPs on performance and power. Standardized by 3GPP, EVS is a new hybrid audio and speech codec with better quality and robustness. Cadence also participated in interoperability tests of the modified EVS called Alternate EVS with the earlier EVS reference code.  Several 3GPP-SA4 committee member companies independently verified the interoperability of EVS based on the latest version of BASOPs called STL2019. The updated EVS codec now called the Alternate EVS reference code has been approved officially by 3GPP as TS 26.452, and the BASOPs as TR 26.973 and ITU-T Rec. G.191 STL.

While the standards work at 3GPP was in progress, Cadence updated our Tensilica HiFi 3z DSP to leverage the benefits of STL2019. This hardware and software codesign resulted in an EVS implementation that is far more efficient than the earlier implementation by a factor of 1.6X. This translates to a significant improvement in mobile phone battery life, which means you can talk or stream mixed audio content longer without having to recharge.

Cadence is continuing to contribute and participate in 3GPP standards for the next-generation codec that will be used in virtual reality applications. Our world is constantly evolving, and the standards that drive technological development must continue to evolve along with it. Despite this continuous change, one constant is that Cadence is committed to providing highly optimized, power-efficient IP and DSP solutions to our customers.

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