Tag: latency
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Latency caused by UDP fragmentation
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While testing a WebRTC application recently, I noticed some unexpected delays in the execution of a series of lines in my OpenSIPS control script. For OpenSIPS to behave properly it is essential that the child threads don’t get blocked and that the lines in the script are executed at speed. Seeing a delay of several seconds during handling of a BYE request (i.e. hangup at one end terminating the call) was therefore quite concerning. Initially, I…
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RTP, Jitter and audio quality in VoIP
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In this article we will briefly look at what RTP is and how it is used to stream VoIP audio. The article then considers how certain network transmission characteristics may introduce jitter or packet loss and the measures that are used in VoIP equipment to mitigate the effects. Other phenomenon which have a bearing on the audio quality on VoIP calls, along with the features used on VoIP equipment to overcome them, are also briefly discussed.…
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VoIP QoS in practice: About Network Congestion
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My previous two articles explored QoS tagging of voice data packets using ToS/DiffServ values and of Ethernet frames using CoS or Priority values. QoS is often advocated as an essential part of any self-respecting VoIP solution and there is no doubt it can make a big difference in the right circumstances. However, it would be a mistake to expect too much of QoS or to assume that it will always make a difference no matter what.…
