AP-VP150 Video Phone Installation and Operation Manual, Edition 1.00
AddPac Technology Proprietary & Documentation
205 - 196
G.711
This specifies the PCM voice coding technique of 64Kbps. Voice is encoded under
G.711 in an appropriate format that enables digital voice transmission over either
PSTN or PBX. G.711 is specified under the ITU-T standard of G-series
recommendation.
G.723.1
This is one of the H.324 standards, and specifies a compression technique that
enables voice or audio signal elements to be compressed at a very low bit
transmission rate. This CODEC is related to the bit transmission rates of 5.3Kpbs and
6.3Kpbs. The high bit transmission rate is based on the MLMLQ technology, and
provides high quality sounds. The low bit transmission rate is based on CELP, and
ensures high flexibility for system designers. This standard is specified under the G-
series ITU-T standard.
G.726
This standard specifies ADPCM coding performed at a rate of 40Kbps, 32Kbps,
24Kbps, or 16Kbps. If the PBX network is configured to support ADPCM, you can
exchange ADPCM encoding voice with packet voice networks, PSTN, or PBX
networks. This standard is specified under the ITU-T standard of G-series
recommendation.
G.728
This standard specifies variations that ensure low delay of CELP voice compression
performed at 16Kbps. The CELP voice coding should be converted to a public
telephony format for transmission over either PSTN or PSTN. This standard is
specified under the ITU-T standard of G-series recommendation, and defines the
CELP compression that encodes G.729 voice to a stream of 8Kbps. G.728 has two
variations (G.729 and G.729 Annex A), and the variations are different in terms of
calculation complexity. The two variations have voice quality similar to ADPCM of
32Kbps. G.728 is specified under the ITU-T standard of G-series recommendation.
Gatekeeper
This is the component of the H.323 video conference system that analyzes a caller
ID, controls access authorization, and manages the subnet bandwidth. A gatekeeper
is H.323 entity that provides the features that enable address conversion and LAN
access control to the H.323 terminal and gateway on LAN. Gatekeepers can provide
other services such as bandwidth control and search for a gateway to the H.323
terminal and gateway. This device manages a device registry on a multimedia
network. The devices are registered with the gatekeeper, and they request the
gatekeeper to authorize a call.
H.225
This ITU standard is applied to the session setting and packetization of H.225.0.
H.225.0 specifies a variety of protocols such as RAS, Q.931, and RTP.
