Jitter Buffer Calculation

Discussion in 'VOIP' started by Jungleboy, Nov 25, 2004.

  1. Jungleboy

    Jungleboy Guest

    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.
     
    Jungleboy, Nov 25, 2004
    #1
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  2. Jungleboy

    Daniel Rakel Guest

    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
     
    Daniel Rakel, Nov 25, 2004
    #2
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