Media5 Mediatrix 4104, Reference Manual

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Chapter 5 - Web Interface – Telephony Voice & Fax Codecs
82 Mediatrix 4104
For instance, if the target jitter value is 50 ms, the maximum jitter is 135 ms and the delay measured
is 130 ms, it would serve nothing to reduce the target jitter. However, if the target jitter value is
100 ms and the measured delay is between 100 ms and 110 ms, then you can lower the target jitter
from 100 ms to 30 ms.
G.711 Codec Parameters
The following are the G.711 codec parameters you can set.

To set the G.711 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.711 section, enable the G.711 u-Law codec by selecting Enable in the G.711 u-Law
choice.
Figure 39: Telephony – G.711 Section
3. Set the minimum and maximum packetization time values for the G.711 u-Law 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.711 u-Law 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.711 u-Law 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.711 a-Law codec by selecting Enable in the G.711 a-Law field.
5. Set the minimum and maximum packetization time values for the G.711 a-Law 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.711 a-Law 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.711 a-Law 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.
6. Enable the G.711 Voice Activity Detection (VAD) by selecting Enable in the G.711 VAD choice.
VAD defines how the Mediatrix 4104 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.
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