G711U and g729 Coding formats

? 711A-codec format is g.711 Alaw

? g711u-codec format is g.711 Ulaw (the default)

? g729-codec format is g.729

? g729a-codec format is g.729a

The above is the use of VoIP codec format, we choose which is better? For different platforms contain different, here monthly network phone selection order preferred: g711u, in our use of Cisco Linksys P2PT testing time, using g729 time. will appear the other side of their own initiative disconnection and then connected to the situation, and the use of g711u is very good to conquer the problem, there is no multiple reconnection situation.

In this test, the network phone subscription may allow many users to play the time interval is too short, so, in order to achieve good results, we recommend that customers use the correct encoding. We provide customers with code from the system of the original g729 to g711u, here we change, first select g711u and then select g729, which is the practice of testing the monthly telephone effect. Assuming the situation is different for you, we will solve the problem of encoding format specifically for you.

We also have the article: Monthly network phone to make it through but can not hear the sound solution inside the problem of this code,

Compression coding is also the focus of the problem, the choice of encoding: g729, g711u and g711a, in order to better improve the sound quality. For example, the assumption here is to use the Dbl gateway.

g729g729aG729abUlawAlawg723.1

It's the sort that's on the top. Because g711u is the meaning of Ulaw, g711a is the meaning of alaw. So we u in front. A in the back. Sort it out to solve the problem of hearing no sound.

This is the solution to the problem of voice packet transmission.

This solution is very good to conquer the monthly telephone network phone can not hear the sound solution, if you are our customers, please contact us. If there is such a problem, please let the two enterprise monthly telephone service for you. Real 100% High quality 24 hours a day to call the Internet phone.

G711 G723 G729 Line account for how much bandwidth problem

Bandwidth= Package length x number of packets per second
= Package length x (1/pack cycle)
= (Ethernet head +ip head +udp +RTP head + payload) x (1/pack cycle)
= (208bit +160bit+64bit+96bit + payload) x (1/pack cycle)
= (528bit+ (packing period (seconds) x bits per second) x (1/pack cycle)
= (528/pack cycle) + bits per second
According to the above calculation formula:
G711:20MS packaging.Bandwidthfor (528/20 +) kbit/s=90.4 kbit/s
G729:20MS Packaging,Bandwidthfor (528/20 + 8) kbit/s= 34.4 kbit/s
g723:5.3k. 30MS Packaging,Bandwidthfor (528/30 + 5.3) kbit/s=22.9 kbit/s
The industry generally according to the following table provides the IP networkBandwidthCoefficients and EthernetBandwidthCoefficients to design the networkBandwidth：
Codec technology compression rate (Kbps) packaging period (MS) IP networkBandwidthFactor EthernetBandwidthCoefficient
G.711 a/u 64 20 1.25 1.41
g.729 A/b 8 20 0.38 0.54
g.723.1 (5.3kbit/s) 5.3 30 0.27 0.37
g.723.1 (6.3kbit/s) 6.3 30 0.25 0.36
H.263 (384kbit/s) ≈384 10 6 6.2
Note: When using a certain encoding method. Use 64K times the correspondingBandwidthCoefficients can be used to derive the actualBandwidth。 Assuming, of course,RelayInterface, it is also necessary to consider the signaling occupation of certainBandwidth, usually calculated according to 2.5%.


If you do not understand the above calculation method, just remember the following results:
G711 actual occupancyBandwidth90.4KBIT/S 100 lines per line concurrently occupying 9Mbps
G729 actual occupancyBandwidth34.4KBIT/S 100 lines per line concurrently occupying 3.4Mbps
G723 actual occupancyBandwidth22.9KBIT/S 100 lines per line concurrently occupying 2.2Mbps

G711U and g729 Coding formats