Audio Codecs, a new Belfast-based company and the developers of the Skylark digital audio data compression algorithm designed for low latency, joined forces with Virscient, a New Zealand based RF consultancy house, to launch a new wireless audio transmission module using Bluetooth Low Energy. The solution uses a Nordic Bluetooth LE SoC to transmit a 24-bit/48kHz high quality, low latency digital wireless microphone signal.
For now, the concept was basically a consortium demonstration to show the potential of a combination of key technologies from different companies, which have in common the same vision. The effort is lead by entrepreneur Jonny McClintock (former head of aptX licensing efforts at APT, CSR and Qualcomm, over a period of nearly three decades). That vision is to reevaluate the possibilities for high quality digital audio transmission for next-generation applications, from very simple, one-channel and low latency microphone signals over Bluetooth LE, all the way to Ultra WideBand (UWB) applications for high-resolution audio in Headphone 3.0 and hearable applications.
The first demonstration of the potential of Audio Codecs’ Skylark efficiency was prepared for the IBC 2022 show that recently reconvened in Amsterdam. And in that professional environment, Jonny McClintock knew that it would make sense to show the possibilities or a robust wireless microphone solution working in combination with Antennaware’s Bodywave RF antenna, created specifically to address the effects of “body blocking” which results in highly annoying audio drop outs, and to ensure a significantly more robust link.
Skylark is a low latency mono audio codec which can be multiplexed together for multichannel, bidirectional applications, supporting multiple cases when low latency is a key requirement, such as for gaming or professional audio applications. In many such environments, it makes sense to simply use a module that supports dual-channel (2.4GHz / 6.5Ghz) Bluetooth LE and UWB radios. Low latency is also a key requirement in 5.1 channels and voice applications with return channel, an area were Skylark enables reaching between 2ms, 5ms or 10ms transmission, depending on how critical are the synchronization and resilience requirements.
The demonstration module shown at IBC is based around the Nordic nRF53 platform where Skylark is running on the application processor. Virscient added their own proprietary RF middleware, which combined with the inherent resilience of the Skylark codec, and the additional 20dB of gain due to Bodywave antenna, ensures a rock-solid Bluetooth RF link. This solution of platform, antenna and codec will offer performance figures which were considered almost impossible due to the vagaries of Bluetooth operating in the cluttered 2.4GHz spectrum.
Boasting latencies of less than 10ms (audio in / audio out) and with the additional RF gains, this proof-of-concept module could be perfect for the Vlogger market and a suitable candidate for Gaming and Karaoke applications. Based on the Nordic platform, developers will have the dual benefit of working with a popular platform while enjoying professional grade audio performance, which also supports control over Bluetooth.
“Leveraging a popular Bluetooth Low Energy platform and using the exceptional design skills of the Virscient team, demonstrates the values of the Bodywave RF and Skylark audio codec. The end user will enjoy a rock-solid link and incredible audio all done at a previously impossible 10ms,” states Jonny McClintock. “We are planning to reduce the latency further and will also be supporting alternative RF frequencies such as UWB. This combines beautifully to address the rapidly emerging Headphone 3.0 market,” he continues.
A New Journey
Having worked in the consumer, broadcast, film, and audio industries for more than 30 years, the majority of that time Jonny McClintock was involved in the marketing and selling of aptX. He has recently left Qualcomm and is currently the Commercial Director for AntennaWare, and he has a consulting role with Sonical.ai. His passion is driving start-ups and his journey is now also expanded to Audio Codecs Ltd, which involves going back to licensing an audio codec. In this case, working with some of the pioneers of the audio compression technology that was also at the foundation of aptX.
Skylark was specifically designed to meet the application needs of radio microphones, and is a well proven audio codec which has been used by many high profile digital wireless microphone manufacturers. The codec meets all of the needs of performers and production teams, and is available on a variety of DSP platforms. A true low latency, high quality, robust audio codec for digital wireless applications that uses “natural” ADPCM error resilience and encodes small blocks of audio combined with special techniques for the non-ADPCM parts. McClintock believes the potential for Skylark in wireless transmission of audio is still untapped, offering an unrivaled combination of audio quality, super low delay and robustness to transmission errors.
Apart from Jonny McClintock, which now leads Audio Codecs, we find familiar names as Peter Craven and Malcom Law. Both are part of the history of data compression from the University of Oxford and their work with Algol Applications, Ltd, leading to the development of Adaptive Differential Pulse-Code Modulation (ADPCM) technology. Peter Craven has recently been awarded a Fellowship by the Audio Engineering Society, “In recognition of significant contributions over many years to signal processing technologies that advance high quality audio, and for co-design of the Soundfield Microphone.”
In 1996 Malcolm and Peter started work with Bob Stuart (of Meridian Audio) on Lossless Data Compression, resulting in the MLP lossless compression system (rebranded as Dolby TrueHD) and subsequently on the MQA audio transmission system. Peter and Malcolm believe basing an audio codec around a large time to frequency transformation is a strategic mistake so have never got involved with the mainstream audio codecs. They have improved the original 80s aptX codec to become the 16 and 24 bit versions that became the benchmark for audio quality over Bluetooth.