G711U and g729 comparing encoded 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 including different, here monthly network phone selection order preferred: g711u, in our use of the Cisco Linksys P2PT test, when using g729, the other side automatically disconnected and then connected to the situation, and the use of g711u is a good solution to the problem, There are no multiple reconnection cases.

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 code, we provide customers with the code from the system of the original g729 to g711u, here we modify, first select g711u and then select g729, This is the practice test of the monthly phone effect, if the situation is different for you, we will be more detailed for you to solve the problem of encoding format.

We also have the article: Monthly network phone to make it through but can't hear the sound solution inside the question of this coding,

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, such as here if the use of 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 are in front of you, a in the post, a sort of good can be resolved to listen to the problem of sound. This is the resolution of The voice packet transmission.

This solution is a good solution to the monthly subscription network phone can not hear the sound solution, if you are our customers, please contact us, if there is such a problem, please let 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
In accordance with 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 follows the IP network provided in the table belowBandwidthCoefficients 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 coding method, use 64K times the correspondingBandwidthCoefficients can be derived from the actualBandwidth。 Of course, if it isRelayInterface, you also need to consider signaling to occupy a 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 comparing encoded formats