Microchip Debuts dsPIC30F Speech Compression and Decompression Library

6/2/2005 - Microchip Technology Inc., a leading provider of microcontroller and analog semiconductors, announced a speech encoding (compression) and decoding (decompression) library for its 16-bit dsPIC® Digital Signal Controllers (DSCs). The dsPIC30F Speech Encoding/Decoding Library is based on the Speex open source compression format, and achieves a 16:1 compression ratio and toll quality speech (PESQ 3.7-4.2). The dsPIC30F Speech Encoding/Decoding Library enables embedded designers to transmit more messages over a given bandwidth, or store longer amounts of speech in a given memory space, while maintaining excellent sound quality and intelligibility.

Many design engineers are seeking to add speech compression to their bandwidth- or memory-constrained applications, but have opted for lower compression methodologies to avoid a stiff per-unit royalty for the intellectual property. The dsPIC30F Speech Encoding/Decoding Library offers a significant cost reduction over competitive options, and brings non-royalty bearing 8 kbps encoding to the embedded world.

"By adapting the open-source Speex audio compression format, we are providing dsPIC DSC users with low-cost, high-quality compression capability from the open source free software community," said Sumit Mitra, vice president of Microchip's Digital Signal Controller division. "Our customers are very cost conscious and will appreciate the ability to add or improve speech compression with a non-royalty bearing pricing structure."

Any embedded application that transmits voice over limited bandwidth or has memory constrained playback can benefit from this speech compression/decompression library. Specific example applications include: voice over IP, tapeless answering machines, voice announcement systems, medical equipment, appliances, building and home safety systems, intercoms, and proprietary communications equipment.

The library has a well-documented Application Programmer's Interface (API) that makes it easy to incorporate speech compression and/or decompression into an application. The library also supports optional voice activity detection.

The speech encoder samples data at 8 kHz, using either the dsPIC DSC's on-chip 12-bit analog-to-digital converter or a 16-bit input obtained from an external CODEC, via the on-chip codec interface port. The encoder achieves up to a 16:1 compression ratio and generates a fixed 8 kbps output rate.

Output of decoded speech can be accomplished using the dsPIC DSC's standard PWM or via the interface to an external CODEC. The encoder requires 19 MIPS (worst case), 33 Kbytes of program memory and 6.2 Kbytes of RAM. The decoder requires 3 MIPS, 15 Kbytes of program memory, and 3.2 Kbytes of RAM.

Storing speech requires 1 Kbyte of memory for each second of speech. The library permits the compressed speech data to be stored in on-chip memory (Flash, EEPROM or RAM) or to an external Flash memory.

Playback-only applications can benefit from a PC-based speech encoder utility that is included on the library CD. This utility creates encoded speech files from a PC microphone or WAV files.

Related Development Tools and Devices
The dsPICDEMTM 1.1 General Purpose Development Board (DM300014) can be used to evaluate this library. The following dsPIC DSCs have the on-chip resources needed for this library: dsPIC30F5011, dsPIC30F5013, dsPIC30F6011, dsPIC30F6012, dsPIC30F6013 and dsPIC30F6014.

Availability and Pricing
All licensing options for the dsPIC30F Speech Encoding/Decoding Library are immediately available. Among these options is a one-year evaluation/development license, which is unaltered from the library that is used for production and can be purchased online at http://buy.microchip.com. The evaluation/development version of the dsPIC30F Speech Encoding/Decoding Library (SW300070-EVAL) is $5USD. Industry-unique, one-time-fee licensing options are also available for production, which runs counter to the per-unit royalty business model that is common for this class of library. Starting at $2,500USD for 5,000-unit production, the license fee that Microchip charges is attractive to many customers since it is a fraction of the cost they would incur developing it themselves.

These one-time fees are based on the estimated lifetime volume of products derived from the product development effort that uses the library. For additional pricing or other information, contact any Microchip sales representative or authorized worldwide distributor, or visit Microchip's Web site at www.microchip.com/dspic.

About Speex Open Source Free Software
Speex is copyrighted by Jean-Marc Valin / Xiph.Org Foundation and it is available under the Xiph.org variant of the BSD license. For more information about Speex, go to www.speex.org/fsos.html.

About dsPIC Digital Signal Controllers
The dsPIC digital signal controller is a 16-bit (data) modified Harvard RISC machine that combines the control advantages of a high-performance 16-bit microcontroller with the high computation speed of a fully implemented DSP to produce a tightly coupled single-chip, single-instruction stream solution for embedded systems design. All dsPIC30F DSCs integrate Flash program memory and most have EEPROM data storage. For more information on the dsPIC DSC family, please visit: www.microchip.com/dspic

About Microchip Technology
Microchip Technology Inc. (NASDAQ: MCHP) is a leading provider of microcontroller and analog semiconductors, providing low-risk product development, lower total system cost and faster time to market for thousands of diverse customer applications worldwide. Headquartered in Chandler, Arizona, Microchip offers outstanding technical support along with dependable delivery and quality. For more information, visit the Microchip website at www.microchip.com.

The Microchip name and logo, and dsPIC are registered trademarks of Microchip Technology Inc. in the USA and other countries. dsPICDEM is a trademark of Microchip Technology Inc. in the USA and other countries.

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