Jitter And Dejitter Buffer - Patton electronics SmartWare R.3.20 Software Configuration Manual

SmartWare Software Configuration Guide
40 • VoIP profile configuration
Voice Packets
Node
Network Node
Node Node
x x + dx
Buffer
Voice
Decoder
x
Figure 80. Jitter and dejitter buffer
The dejitter buffer delays incoming packets so it can present them to the decompression algorithm at fixed
intervals. It will also fix any out-of-order packets by looking at the sequence number in the RTP packets. Such
buffering has the effect of smoothing packet flow, and increasing the resiliency of the codec to packet loss,
delayed packets, and other transmission effects. The negative side of dejitter buffering is that it can add signifi-
cant delay. The dejitter buffer size is configurable and can be optimized for given network conditions, the size
is usually set to be a multiple of the expected packet arrival time in order to buffer an integral number of pack-
ets. It is not uncommon to see dejitter buffer settings around 80 ms for each direction.
VoIP profile configuration task list
514