5th etsi speech Quality Test Event Anonymous Test Report

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3.4G.729 Speech Coder

The G.729 speech coder was also tested with 20 ms packet length. This setting is identical to the previous speech quality test events. The results can therefore directly be compared to the corresponding average, minimum and maximum scores from the 4^th SQTE [16].

Table 4.2 shows the TMOS respectively MOS-LQO results measured under the different IP network conditions. Again minimum, average and maximum scores are calculated in table 4.2.

G.729 – TMOS (TOSQA2001) and MOS-LQO (P.862.1), 20 ms, VAD off (except condition 0a), PLC on
	Delay [ms] / PL / jitter [ms]	TMOS			MOS-LQO			One way delay (ms)
	Delay [ms] / PL / jitter [ms]	Min	av.	max	min	av.	max	Min	av.	max
0a VAD	0 / 0% / 0	3.6	3.6	3.6	3.7	3.7	3.8	54.3	72.5	95.7
1a	0 / 0% / 0	3.5	3.6	3.6	3.8	3.8	3.8	54.3	71.9	86.8
2a	0 / 1% / 0	3.4	3.5	3.5	3.6	3.6	3.6	55.9	79.3	122.9
3a	0 / 2% / 0	3.2	3.3	3.4	3.4	3.5	3.5	54.3	70.3	87.2
4a	0 / 3% / 0	3.2	3.2	3.3	3.3	3.3	3.4	54.3	72.2	91.3
5a	0 / 5% / 0	3.0	3.1	3.2	3.1	3.1	3.2	54.3	71.8	87.4
6a	50 / 1% / 20	2.2	3.2	3.5	2.1	3.3	3.6	84.9	113.9	137.4
	G.729 ref.	---	3.6	---	---	3.8	---	---	---	---

Table 4.2: TMOS (TOSQA2001) and MOS-LQO results calculated using PESQ (according to ITU-T Recommendation P.800.1 and P.862.1), G.729 speech coder, 20 ms packet length (PL)

The graphical analyses for the G.729 listening speech quality can be found in figure 4.4 (TMOS) and 4.5 (MOS-LQO) respectively.

Fig. 4.4: TMOS results calculated using TOSQA2001; G.729, 20 ms PL

Fig. 4.5: MOS-LQO results calculated using PESQ (P.862.1); G.729, 20 ms PL

The results can be summarized as follows:

The TMOS respectively MOS-LQO can be seen as identical for the tested gateways under test under clean network conditions. The delay varies between approximately 55 ms as minimum and 85 ms respectively 95 ms as maximum.
The quality differences indicated by the highest and lowest TMOS and MOS-LQO respectively are negligible for the different packet loss test condition. This could be expected due to the fact that the packet loss concealment is integral part of the codec itself.
The jitter influence in the network leads to very high differences up to 1.5 points on the TMOS respectively MOS-LQO scale. This is mainly caused by the configuration in one gateway.

The average TMOS and MOS-LQO results are compared for the G.729 speech coder in figure 4.6. As for the G.711 speech coder both analyses methods lead to similar results and show the known tendency: TOSQA2001 (TMOS) rates slightly more critical than PESQ (MOS-LQO). This relation was already observed during previous events [16].
	Fig. 4.6: TMOS vs. MOS-LQO (G.729, average)

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