Java source code for calculating E
The Mean Opinion
Score (MOS) test is a well acccepted standard which is defined in the ITU-T
Rec.P.800.
The value of MOS
test is generated by letting large number of listeners to evaluate the quality
of the test sentences.
The test scores
are averaged to a mean score which range from 1 to 5, 1 being the worst and 5 being
the best.
The E-model which is
defined by ITU-T Rec.G.107 is a computational model converting all parameters
that affect a voice call into a single rating value R.
A VB source code was provided in G.107 for calculating R value. But considering not everybody knows VB, I would like to share some java code I used before.
public class VoIPCalculator {
/**
* This function returns R value calculated by using the passed in parameters
* See detail of each parameter in ITU-T G.107
* @param T
* @param Ppl
* @param SLR
* @param RLR
* @param Ds
* @param STMR
* @param Dr
* @param TELR
* @param WEPL
* @param Ie
* @param BPL
* @param BurstR
* @param A
* @param Nc
* @param Ps
* @param Pr
* @param qdu
* @param Nfor
* @return
*/
private static double calRValue(double T, double Ppl, double SLR,
double RLR, double Ds, double STMR, double Dr, double TELR,
double WEPL, double Ie, double BPL, double BurstR, double A,
double Nc, double Ps, double Pr, double qdu, double Nfor) {
double LSTR = STMR + Dr,
Tr = 2*T,
Ta = T;
double Nfo = Nfor + RLR;
double OLR = SLR+RLR;
double Pre = Pr + 10*Math.log10(1+Math.pow(10,
((double)(10-LSTR))/(double)10));
double Nor = RLR - 121 +Pre
+ 0.008*Math.pow((Pre-35),2);
double Nos = Ps - SLR -Ds
- 100 +0.004*Math.pow((Ps-OLR -Ds - 14),2);
double No = 10*Math.log10((Math.pow(10, (double)Nc/(double)10))
+Math.pow(10, (double)Nos/(double)10)
+Math.pow(10, (double)Nor/(double)10)
+Math.pow(10, (double)Nfo/(double)10));
double Ro = 15 - 1.5*(SLR+No);
double Q = 37 - 15*(
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{
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r ......
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2009-04-14 15:37
虽然现在用APACHE COMMONS DBCP可以非常方便的建立数据库连接池，
但是像这篇文章把数据库连接池的内部原理写的这么透彻，注视这么完整，
真是非常难得，让开发人员可以更深层次的理解数据库连接池，真是非常感
谢这篇文章的作者。
import java.sql.Connection;
import java.sql.DatabaseMetaData;
......
