dpq / gsmfr-as3

GSM Full-Rate codec in AS3

gsmfr-as3

ETSI GSM 06.10 RPELTP (Regular Pulse Excitation-Long Term-Prediction-Linear Predictive Coder) Speech Coder Implementation

Coding Rate: 13.2kbps
Sampling Rate: 8000Hz
Input: 16 bit PCM (Note: GSM-FR codec uses major 13 bits only)

Encoding:

var encoder: GSMEncoder = new GSMEncoder();
var data: Vector<int> = readSamples(); // 160 samples of PCM 8000Hz 16bit
var frame: ByteArray = encoder.encode( data ); // 33 bytes of GSM-FR encoded data

Decoding:

var decoder: GSMDecoder = new GSMDecoder();
var frame: ByteArray = readBytes(); // 33 bytes of GSM-FR encoded data
var data: Vector<int> = decoder.decode( frame ); // 160 samples of PCM 8000Hz 16bit