Jitter buffers are used to counter packet-delay-variation (PDV or jitter) introduced by queuing in packet-switched networks when a continuous stream of audio (or video) is transmitted over the network. Packets, by nature of the TCP/IP protocol that most data-networks are developed around, may see these UDP packets arrive at the endpoint late, out of order, or not at all. The maximum jitter that can be countered by a jitter buffer is equal to the buffering delay introduced before starting the play-out of the media stream.
Some systems use sophisticated delay-optimal jitter buffers that are capable of adapting the buffering delay to changing network jitter characteristics. These are known as adaptive de-jitter buffers and the adaptation logic is based on the jitter estimates calculated from the arrival characteristics of the media packets.
On a VOIP network, jitter buffers are integrated at endpoint devices and if it is a fixed configuration, the jitter buffer is typically 30ms to 50ms in maximum size while an adaptive buffer may be set up to 100ms. Jitter buffers larger than 100ms tend to introduce noticeable delays into the conversation.
