Network Delay; Network Jitter; Packet Loss; Use Of Multicast - JVC 4ch Network Encoder VN-E4 Instructions Manual

Preparation
(continued)

2-2 Network Delay

When the client acquires JPEG or audio via TCP, VN-E4 will be send out data while checking the ACK from the client at the same
time. For networks with considerable delay, data cannot be sent out until ACK is received, and therefore the frame rate will drop.
To operate VN-E4 and its built-in viewer using the factory settings, the frame rate will drop below 120 fps if the round trip time
exceeds 4 msec. Enlarging the window scale of the PC on which the built-in viewer is running may extend the round trip time for
which frame rate deteriorates to 20 msec. Refer to the section on A7. TroubleshootingB in AOthersB for details on the window scale.
Drop of frame rate by network delay can be eliminated by using multicast.

2-3 Network Jitter

When there is considerable network jitter, delay time may be prolonged, frame rate may drop and audio sound may be
interrupted.
There are 3 types of buffer that may be chosen for the built-in viewer, namely 0.3, 0.6 and 1.0 second. Influences of jitter may be
reduced by setting to a larger value. In this case, however, delay time will be prolonged.

2-4 Packet Loss

When acquiring images/audio from VN-E4 via TCP, packet loss may be recovered by resending from TCP. When there is
considerable delay during resending, however, image frame rate may drop and audio sound may be interrupted.
When packet loss occurs during multicast sending from VN-E4, image frame rate may drop and audio sound maybe interrupted.

2-5 Use of Multicast

Make use of a network that supports IGMP if multicast is to be used. When a network that does not support IGMP or multicast
routing is used, multicast data that is sent out from VN-E4 may not reach the recipient and playback may fail.
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