Definetion - In VoIP, a jitter buffer is shared data area where voice packages can be collected, stored, and sent to the voice processor in evenly spaced intervals. Variations in packet arrival time, called jitter, can occur because of network congestion, timing drift, or route changes.

The jitter buffer, which is located at the receiving end of the voice connection, intentionally delays the arriving packets so that the end user experiences a clear connection with very little sound distortion.

There are two kinds of jitter buffers, static and dynamic. A static jitter buffer is hardware-based and is configured by the manufactures.

A dynamic jitter buffer is software-based and can be configured by the network administrator to adapt to changes in the network's delay.

 

在voice over IP(VoIP)中，抖动缓冲器是一个共享的数据区域，在这个数据区域中，每隔一段均匀的间隔，语音包会被收集，存储 并发到语音处理器。包到达时间的变化，称作抖动，将会由于网络 拥 塞，定时漂移或路由变更而产生。抖动缓冲器放于语音连接的接收端，它有意地延迟到达的包，如此一来，终端用户就会感受到一个清晰的，没有什么声音失真的连 接。抖动缓冲器有两种，静态的和动态的。静态抖动缓冲器是基于硬件的，它是由厂家来配置的。而动态抖动缓冲器是基于软件的，它由网管配置以适应网络延迟的 改变。

 

Problem: Jitter Buffer

A jitter buffer temporarily stores arriving packets in order to minimize delay variations. If packets arrive too late then they are discarded. 

A jitter buffer may be mis-configured and be either too large or too small.

 

Impact

If a jitter buffer is too small then an excessive number of packets may be discarded, which can lead to call quality degradation. If a jitter buffer is too large then the additional delay can lead to conversational difficulty.

 

Resolution

A typical jitter buffer configuration is 30mS to 50mS in size. In the case of an adaptive jitter buffer then the maximum size may be set to 100-200mS. 

Note that if the jitter buffer size exceeds 100mS then the additional delay introduced can lead to conversational difficulty.