Цитата(harris @ 27.6.2011, 15:50)
ОК. А как это полагается делать по стандарту???
примерно так
6.2.5 Audio codec
All H.323 terminals shall have an audio codec. All H.323 terminals shall be capable of encoding and decoding speech according to Recommendation G.711. All terminals shall be capable of transmitting and receiving A-law and *-law. A terminal may optionally be capable of encoding and decoding speech using other audio codecs which can be signalled via H.245 negotiation. The audio algorithm used by the encoder shall be derived during the capability exchange using H.245. The H.323 terminal should be capable of asymmetric operation for all audio capabilities it has declared within the same capability set, e.g. it should be able to send G.711 and receive G.728 if it is capable of both.
If G.723.1 audio is provided, the audio codec shall be capable of encoding and decoding according to both the 5.3 kbit/s mode and the 6.3 kbit/s mode.
то есть, парами, видимо. цыска примерно так и делает, только в разговоре переключать не умеет:
G.723.1 Codec Issues
There are two versions of G.723.1 called Annex-A and non Annex-A. These versions do not interoperate. G.723.1 Annex-A includes a built-in IETF VAD algorithm and CNG.
Also, in Cisco IOS Software Release 12.0(5)T and later, the G.723.1 codec is supported with a 5.3 kbps and 6.3 kbps rate. When a Cisco VoIP gateway sets up a call between devices that use G723.1, it is concerned only that the far-end uses G.723.1. Neither side is concerned with the 5.3 kbps or 6.3 kbps rate that is supported by the other side. This means that, while it is beneficial to have both sides support the same rate, it is possible that one side transmits at 5.3 kbps and the reverse direction transmits at 6.3 kbps. The speed that is used is viewed with the show call active voice brief command as shown here:
Cisco-router# show call active voice brief
47 : 494514hs.1 +473 pid:0 Answer active
tx:210/5040 rx:219/4380
IP 5.5.0.1:16534 rtt:3ms pl:890/0ms lost:0/0/0 delay:70/70/70ms g723r63
47 : 494514hs.2 +473 pid:1 Originate 4750001 active
TX:230/1840 rx:230/8280
Tele 2/0:0 (35): TX:6870/2290/0ms g723r63
!--- In this example the G.723.1 is operating at 6.3 kbps.
noise:0 acom:0 i/0:-79/-5 dBm
The G.723.1 standard allow stations to change rates between 6.3 kbps and 5.3 kbps during a call to adjust to network traffic loads. The Cisco VoIP gateways do not support this functionality. But they do understand if the remote device (such as a Cisco IP Phone) transmits at a different rate than was originally negotiated.
These G.723.1 codec combinations interoperate:
G.723.1 (5.3 kbps) and G.723.1 (6.3 kbps)
G.723.1 (5.3 kbps) and G.723.1 (5.3 kbps)
G.723.1 (6.3 kbps) and G.723.1 (6.3 kbps)
G.723.1 Annex-A (5.3 kbps) and G.723.1 Annex-A (6.3 kbps)
G.723.1 Annex-A (5.3 kbps) and G.723.1 Annex-A (5.3 kbps)
G.723.1 Annex-A (6.3 kbps) and G.723.1 Annex-A (6.3 kbps)