Java source code for calculating E-Model R value

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*(Math.log10(qdu)); double G = 1.07+0.258*Q+0.0602*Math.pow(Q, 2); double Z = (double)46/(double)30-G/(double)40; double Y = (double)(Ro-100)/(double)15+46/8.4-G/9; double Iq = 15*Math.log10(1+Math.pow(10, Y) +Math.pow(10, Z)); double STMRo = -10*Math.log10(Math.pow(10, -STMR/(double)10) + Math.exp(-T/(double)4)*Math.pow(10, -TELR/10)); double Ist = 12*Math.pow((1+Math.pow((STMRo-13)/(double)6, 8)), 1/(double)8) -28*Math.pow((1+Math.pow((STMRo+1)/19.4, 35)), 1/(double)35) -13*Math.pow((1+Math.pow((STMRo-3)/33, 13)), 1/(double)13) +29; double Xolr = OLR+0.2*(64+No-RLR); double Iolr = 20* (Math.pow((1+Math.pow((Xolr/8),(double)8)), ((double)1/(double)8))-Xolr/(double)8); double Is = Iolr + Ist + Iq; double TERV = TELR - 40*Math.log10((1+T/10)/(1+T/150) +6*Math.exp(-0.3*Math.pow(T,2))); double Idd = 0; if (Ta>100) { double X = Math.log10(Ta/(double)100)/Math.log10(2); Idd = 25 * (Math.pow((1+Math.pow(X, 6)), 1/(double)6)-3*Math.pow((1+Math.pow(X/(double)3, 6)), 1/(double)6)+2); } if (STMR<9) TERV = TERV + 0.5*Ist; double Rle = 10.5 * (WEPL+7)*Math.pow(Tr+1, -0.25); double Idle = (Ro-Rle)/(double)2 + Math.sqrt(Math.pow(Ro-Rle, 2)/4+169); double Roe = -1.5*(No-RLR); double Re = 80+2.5*(TERV-14); double Idte = ((Roe-Re)/2 + Math.sqrt(Math.pow(Roe-Re, 2)/(double)4+100) -1)*(1-Math.exp(-T)); if (STMR > 20) Idte = Math.sqrt(Math.pow(Idte,2)+Math.pow(Ist,2)); double Id = Idte + Idle + Idd; double Ieef = Ie+(95-Ie)*(Ppl/((Ppl/BurstR)+BPL)); double R = Ro - Is - Id - Ieef +A; return R; } /** * Using default values recommended by ITU-T in G.107 * @param T mean one-way delay * @param Ppl packet-loss probability * @return */ public static double calRValue(double T, double Ppl) { double SLR = 8, RLR = 2, Ds = 3, STMR = 15, Dr = 3, TELR = 65, WEPL = 110, Ie = 0, BPL = 1, BurstR = 1, A = 0, Nc = -70, Ps = 35, Pr = 35, qdu = 1, Nfor = -64; return calRValue(T, Ppl, SLR, RLR, Ds, STMR, Dr, TELR, WEPL, Ie, BPL, BurstR, A, Nc, Ps, Pr, qdu, Nfor); } /** * This function calculates MOS value from R value * @param R * @return */ public static double calMOSValue(double R) { double mos = 0; if (R<0) mos =1; else if (R>100) mos = 4.5; else mos = 1 + 0.035*R +R*(R-60)*(100-R)*7*Math.pow(10, -6); return mos; } public static void main(String... Args) { //assume mean one way dealy is 150ms, Packet-loss Probability is 0.01 double T=150; double Ppl=0.01; double R = calRValue(T,Ppl); double MOSValue = calMOSValue(R); System.out.println("when one way delay is "+T+" and Packet-loss Probability is "+Ppl +", R vlaue is "+R+", MOS value is "+MOSValue); } }