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Jungleboy 11-25-2004 11:25 AM

Jitter Buffer Calculation
 
Can anybody help me in Jitter buffer calculation??

I want to know how to calculate Jitter Buffer from ICMP Latency. Means
if you are getting a latency of 300ms through Ping then what should be
the Jitter buffer and how to calculate it.

Daniel Rakel 11-25-2004 05:13 PM

Re: Jitter Buffer Calculation
 
Jungleboy wrote:

> I want to know how to calculate Jitter Buffer from ICMP Latency. Means
> if you are getting a latency of 300ms through Ping then what should be
> the Jitter buffer and how to calculate it.


It depends on the bit rate and the size of the packets. E.g., If
you have a 64 Kbit/s voice transmission, you can play 19200 bit in
300 ms. For a R bit/s connection and a worst-case jitter of J seconds, you
need a buffer of at least 2*J*R bit. An attempt of an explanation:

Before start playing, you should wait the jitter time of 300 ms to avoid
breaks, because the first packet(s) could be much to early, but the next
ones much too late. So you need at least a buffer of 19,2 Kbit to bridge
the gap. But maybe, actually the first packet(s) came much to late, but
you waited for the jitter time of 300 ms (because you don't know if the
packet comes to early, on time or to late) and the next ones come much to
early. To avoid a buffer overrun, you must have place for additional 19,2
Kbit of data. So your buffer needs to be at least 38,4 Kbit (4800 Byte).
Dependening on the size of the packets, you need to round up the buffer
size to a multiple of a packet size, because you cannot store only a part
of a packet.

Regards,
Daniel


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