Audio transmitted across Bluetooth could provide “perfect, audiophile-quality sound” as soon as next year, according to Open Interface North America Inc. (OINA). The company claims its proprietary, patent-pending “SOUNDabout Lossless” Bluetooth codec to be capable of delivering remote digital audio that is “bit for bit” faithful to the original.

OINA's codec is intended to replace the Subband Codec (SBC) originally specified as part of Bluetooth's A2DP (Advanced Audio Distribution Profile). According to OINA, SBC is a “lossy” codec that discards data in order to fit audio into a bandwidth 345 Kbps or less.

Although SBC usually does its intended job of saving power and maintaining lip sync in video, it delivers poor sound, as users of Bluetooth headphones know. That's particularly true, OINA said in a statement, when they are playing media encoded in MP3, AAC, or other lossy formats. These combine with SBC to provide unpleasant compression artifacts.

OINA says its SOUNDabout Lossless codec contrasts to this by sacrificing no audio information, yet occupying bandwidth less than 510 Kbps. The company claims that power consumption is nonetheless relatively low, since SOUNDabout Lossless can run on a processor as lightweight as a 20MHz ARM7TDMI core (roughly 20 MIPS performance) — little more than an efficient implementation of SBC. Additionally, its footprint is small, around 6KB.

OINA claims its codec also achieves low latency, unlike other lossless codecs such as ALAC and FLAC. It can compress and decompress audio in near real-time, (Free Lossless Audio Codec), neither of which achieves low-latency.

When listening to audio on a video clip, the audio should be no more than 40 milliseconds behind the video, OINA asserts. SOUNDabout Lossless is said to have an encoding latency under 10 milliseconds in all encoding modes, going as low as 2 milliseconds, allowing for highly accurate synchronization of picture and sound.

OINA CTO Breg Burns stated, “Wireless stereo headphones, for example, can now have exactly the same performance as a wired headphone.”

Although initially implemented for Bluetooth 2.0, Burns points out that the SOUNDabout Lossless codec is also suitable for storage or WiFi transmission of media files. Mobile phones, MP3 players, wireless headsets and headphones, speakers, and car stereo systems are all cited as possible applications.

In addition to the SOUNDabout Lossless codec, OINA's SOUNDabout suite includes the eSBC codec, an alternative codec that enhances quality but is compatible with existing Bluetooth headphones and other devices. The suite also includes a SOUNDabout application development platform and the company's BLUEmagic protocol stack.

SOUNDabout Lossless is currently implemented on the x86 and ARM7 TDMI architectures, and is available for evaluation. Other platforms, including Broadcom's BCM2047, CSR's BlueCore5-Multimedia, Renesas's SuperH Family, and STM's STA529BT, will be available for evaluation beginning in the next several months, the company said.

The codec will normally be delivered in OS-independent, pre-compiled binaries for supported processor architectures, but it is implemented in ANSI C code, allowing the company to support ports to other processors, Burns added. It will therefore support embedded Linux, Windows Mobile, Windows CE, and other popular mobile and embedded OSes.

 
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