OINA's lossless audio codec targets Bluetooth apps - Embedded.com

OINA’s lossless audio codec targets Bluetooth apps


Open Interface North America's SOUNDabout Lossless Codec brings audiophile quality to Bluetooth wireless audio by delivering perfect reproduction of streaming audio over a Bluetooth radio link.

The codec requires Bluetooth EDR to run. But unlike other lossless audio codecs such as Apple Lossless Audio Codec (ALAC) and Free Lossless Audio Codec (FLAC), it performs its conversion with extremely low latency for a lossless codec.

This is important for applications that require lip-synch capability such as computer games and wireless headsets used in surround sound entertainment systems. Encoding latency is always under 10 ms and sometimes as low as 2 ms. The usual metric for acceptable lip-synch performance is 40 ms.

SOUNDabout Lossless Audio Codec uses a hybrid sub-band technology to deliver a symmetric, low complexity bit stream. The codec requires only about 20 MIPs on an ARM7 (TDMI) for either encode or decode. Low complexity and high performance also enable real-time transcoding from other audio formats.

Compression ratios range from 30 to 60 percent depending on the audio source.

Compression does not involve sampling the source bit stream followed by algorithm selection. Instead, it applies a set of compression technologies while taking care that each operation is reversible. The compression ratio result is determined by the relative success of the entire process.

Although most source audio is derived from compressed bit streams, at the very least the codec minimizes the artifacts to those that had been introduced earlier. There is also a trend toward providing uncompressed audio, such as the audio on BlueRay discs.

The codec's dynamic range is determined by bit depth of the processor. Typically, this is 16 bits, which provides a dynamic range of 96 dB. But the codec is bit-depth independent and will provide better results on 24-bit processors. Memory resources required are about 6 Kbytes of Flash for ARM code and about 2 Kbytes of RAM.

The codec is currently implemented on the X86 and ARM7 TDMI and is available for evaluation. Other platforms, including Broadcom's BCM2047 and CSR's BlueCore5-Multimedia, will be available for evaluation in the next few months.

Founded in 2000, OINA has produced a Bluetooth Upper Protocol Stack and more profiles than any other vendor. It has also created several proprietary audio products that are fully compatible with the Bluetooth standard but produce significantly better audio quality.

OINA has more than thirty customers in mobile, consumer electronics and automotive. Customers include Alpine, Alps Automotive, LGE, Logitech, Phillips, Qualcomm, Sagem, Samsung, Sharp, Sony and ST Microelectronics.

More information is available at www.oi-us.com.

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