Technical Description of TANDBERG MCU with software version D3
D12925 Rev. 03
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4.1.4.9 IP packet sizes
Audio
The system automatically selects the most favorable IP packet size for audio. Depending on
the network conditions, the system will send 20 ms or 40 ms of audio in each packet, thus:
•
G.711 – 160/320 bytes per packet
•
G.728 – 40/80 bytes per packet
•
G.722 – 160/320 bytes per packet
•
G.722.1 (24 kbps) – 60/120 bytes per packet
•
G.722.1 (32 kbps) – 80/160 bytes per packet
Video
The TANDBERG MCU is sending maximum 1450 bytes of video per packet.
Note:
In addition, the system needs to add the following header information for each of the audio
and video packets above:
20 bytes IP-header, 8 bytes UDP-header and 12 bytes RTP-header (i.e. 40 bytes in total).
Packet loss:
Packet loss
is displayed in the conference overview of the MCU. The number
shown is the average of audio- and video- packets that are lost during the last 2 seconds.
4.1.4.10 Intelligent Packet Loss Recovery (IPLR)
IPLR is an ITU standard based packet loss compensation for H.323 that improves received
video into the TANDBERG MCU. IPLR supports all video protocols and resolutions that
TANDBERG MCU already has implemented and is compatible with all terminals and
Gateways.
IPLR is a special algorithm developed at TANDBERG that will make efforts to reconstruct
the lost packets and reduce the visual effects caused by packet losses.
•
If the MCU experiences packet loss from an endpoint, it will ask the endpoint to handle
packet loss. This requires Intelligent Packet Loss Recovery functionality on the endpoint.
•
If an endpoint experiences packet loss from the MCU, the MCU encoder will not start
IPLR since this would affect the received video quality for all other endpoints.
