Bluetooth To Get Lossless-Audio Upgrade

By Colleen Bohen -- TWICE, 8/1/2007

Seattle – A new lossless-compression codec suitable for low-power Bluetooth devices will improve stereo Bluetooth sound quality and, because of low latency, make Bluetooth suitable for use in applications requiring synchronization between audio and video, the codec’s developer said.

The technology, called SOUNDabout Lossless, would be suitable for wireless speakers in home theater systems and for multimedia applications residing on portable media players (PMPs) and cellphones, said technology developer Open Interface North America (www.oi-us.com). The seven-year-old company specializes in developing software to improve Bluetooth performance, and its solutions are incorporated in multiple consumer products, company chairman Tom Nault said. Apple licenses Open Interface technology, Apple’s web site shows.

With SOUNDabout, audio transmitted over Bluetooth would be bit-for-bit identical to the sound generated by the source, whether CD, HD DVD, Blu-ray Disc, or PMP despite compression of 30 percent to 60 percent, depending on the audio track, said Nault. Bluetooth’s A2DP stereo profile, in contrast, delivers lower quality stereo because it’s based on a low-bit-rate losslessly compressed format, which was approved by the Bluetooth Special Interest Group (SIG) as part of the Bluetooth standard.

The Bluetooth trade group “is satisfied with A2DP as it exists,” and the group has “nothing in the works to improve it,” said Nault. But suppliers who adopt the backward-compatible SOUNDabout technology will be able to offer consumers added value when the technology is incorporated in companion send and receive devices, he said.

SOUNDabout’s compression ratios are similar to those of such lossless-compression codecs as FLAC (free lossless audio codec) and ALAC (Apple Lossless Audio Codec), but SOUNDabout is more battery-efficient and achieves low latency, Nault said.

The SoundaBOUT enhancement is ideal for low-power battery-operated devices because of its code-efficient algorithm, which requires only 20MIPS (millions of instructions per second) of processing power, he explained. As a result, SOUNDabout imposes “very little additional battery drain” compared to Bluetooth. Because it is code-efficient, SOUNDabout enables real-time transcoding from other formats and yields encoding latency of 2-5 milliseconds, enabling “highly accurate synchronization of sound and picture,” he added.

The technology would piggyback on Bluetooth’s EDR (enhanced data rate) version, which accelerates Bluetooth's raw data rate to 3Mbps from 1Mbps and average throughout to 2.1Mbps from 720kbps compared to earlier versions. Bluetooth EDR is twice as efficient as the previous specs.

In home theater applications, one SOUNDabout-equipped transmitter could send audio content to two surround speakers and a subwoofer. Multiple transmitters could be used to cut the wires to more speakers, he added.

SOUNDabout will be available from several chip suppliers in quantity in a matter of months for consumer electronics and cellphone applications, Nault said.