For losses as small as one packet, the DSP interpolates what it calculates the audio should be, making the problem inaudible through the Cisco IOS Packet Loss Concealment (PLC) service. If the magnitude of jitter is so great that packets are received out of range of the playout delay buffer, the out-of-range packets are discarded and dropouts appear in the audio. The playout delay buffer is also referred to as the dejitter buffer. It’s actually irrelevant in almost all scenarios. Now, the key thing to remember is: don’t let jitter freak you out. The DSPs then convert the packets back into an analog audio stream. It should: 44.1kHz is the most common sample rate for MP3 files Low jitter levels result in a truer conversion, and DAC s may often use a separate filter chipset for keeping the digital jitter count low.

The playout delay buffer must buffer these packets and then play them out in a steady stream to the DSPs. Playout delay is the amount of time that elapses between the time a voice packet is received at the jitter buffer on the DSP and the time a voice packet is played out to the codec. The playout delay buffer mechanism handles this function. When a router receives an audio stream for VoIP, it must compensate for any jitter that it detects. Playback may experience gaps while waiting for the arrival of variable delayed packets.ĭejittered Stream Is Sent to DSPs i Cisco Public This variation causes problems for audio playback at the receiving end.

Because of network congestion, improper queuing, or configuration errors, the delay between packets can vary instead of remaining constant, as shown in the figure. The sending side transmits packets in a continuous stream and spaces them evenly apart. Jitter is defined as a variation in the delay of received packets.

What is jitter