Medias Mediatrix 1204, Справочное руководство

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Chapter 5 - Web Interface – Telephony Voice & Fax Codecs
86 Mediatrix 1204
G.729 Codec Parameters
The following are the G.729 codec parameters you can set.
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To set the G.729 codec parameters:
1. Select to which port you want to apply the changes in the drop down menu at the top of the window.
2. In the Voice - G.729 section, enable the G.729 codec by selecting Enable in the G.729 choice.
Figure 40: Telephony – G.729 Section
3. Set the minimum and maximum packetization time values for the G.729 codec in the corresponding
drop-down menu.
The packetization time (also called packetization period or ptime) is the duration, in ms, of the voice
packet.
• Minimum : Shortest packetization period allowed for the G.729 codec. Authorized
values start at 10 ms and come in discrete steps of 10 ms up to the one specified by
the corresponding
Maximum drop-down menu.
• Maximum : Longest packetization period allowed for the G.729 codec. Authorized
values go up to 100 ms, in discrete steps of 10 ms, and start at the one specified by the
corresponding
Minimum drop-down menu.
4. Enable the G.729 Voice Activity Detection (VAD) by selecting Enable in the G.729 VAD choice.
VAD defines how the Mediatrix 1204 sends information pertaining to silence. This allows the unit to
detect when the user talks, thus avoiding to send silent RTP packets. This saves on network
resources. However, VAD may affect packets that are not really silent (for instance, cut sounds that
are too low). VAD can thus slightly affect the voice quality.
G.729 has a built-in VAD in its Annex B version. It is recommended for digital simultaneous voice
and data applications and can be used in conjunction with G.729 or G.729 Annex A. A G.729 or
G.729 Annex A frame contains 10 octets, while the G.729 Annex B frame occupies 2 octets. The
CN packets are sent in accordance with annex B of G.729.
5. Click Submit if you do not need to set other parameters.
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