Specifications

Development Systems Ordering Guide
DS30177T-page 20 © 2005 Microchip Technology Inc.
dsPIC30F Speech Encoding/Decoding Library
The dsPIC30F Speech Encoding/Decoding Library
performs toll-quality voice compression and voice
decompression. The library is based on a modified
version of Speex source code and features a 16:1
compression ratio. It samples speech at 8 kHz and
compresses it to a rate of 8 kbps. Storing compressed
speech for playback requires approximately 1 Kbyte of
memory for each second of speech.
Features
Key features of the library include:
• Fixed 8 kHz sample rate
• Fixed 8 kbps output rate
• PESQ-based Mean Opinion Score: 3.7-4.2 (out of 5.0)
• Code Excited Linear Prediction (CELP)-based coding
• Two analog input interfaces – codec or on-chip
12-bit ADC
• Two analog output interfaces – codec or
on-chip PWM
• Optional Voice Activity Detection
• Playback-only applications will benefit from the
Speech Encoder Utility. It allows you to make
encoded speech files from your desktop using a PC
microphone or WAV file
• Storing compressed speech requires 1 KB of
memory per second of speech
• Off-chip support for playback of long speech samples
• Royalty free (only one-time license fee)
• Full compliance with Microchip MPLAB
®
C30
C Compiler Tools
•
“dsPIC30F Speech Encoding/Decoding Library
User’s Guide”
(DS70154) is provided to help the user
understand and use the library
• Designed to run on dsPICDEM™ 1.1 Demonstration
Board (DM300014)
Resource Requirements
Decoder:
Playback Interface: Si-3000 Audio codec or PWM
Computational Power: 3 MIPS
Program Flash Memory: 15 KB
RAM*: 3.2 KB
Encoder:
Sampling Interface: Si-3000 Audio codec or 12-bit ADC
Computational Power: 19 MIPS (worst case)
Program Flash Memory: 33 KB
RAM*: 5.4 KB (1.2 KB is scratch)
* Full-duplex support is presently not possible due to RAM requirements,
but support will be provided with future devices. Half-duplex support is
now possible and requires 6.8 KB of RAM.
Ordering Information:
SW300070-EVAL dsPIC30F Speech Encoder/Decoder Library Software License (Evaluation Only)
SW300070-5K dsPIC30F Speech Encoder/Decoder Library Software License (Up to 5K units)
SW300070-25K dsPIC30F Speech Encoder/Decoder Library Software License (Up to 25K units)
SW300070-100K dsPIC30F Speech Encoder/Decoder Library Software License (Up to 100K units)
DS70146
“dsPIC30F Speech Encoding/Decoding Library Product Overview”
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