[speex-dev] frame size

[Jean-Marc Valin]

> 20 bytes speex
> 12 bytes ogg headers (and others?)
> 28 bytes UDP/IP headers (2 IP numerbers, 2 portnumbers, checksum, etc, etc)

If you're doing VoIP, there's no Ogg header required. The connection is
setup using SIP or H323 and then you transmit "raw" packets. Ogg is only
used when you're dealing with files.

> Am I overlooking something, or does this fixed frame size mean that
> the "8kbps" in reality means at least 24kbps?
> 
> Or is there something ohphone/gnomemeeting/etc can/should do to
> put more than one fram inside each UDP package?

There are workarounds. For example, you can send two packets at a time
to reduce the overhead (at the expense of latency), but most of the time
people transmit one packet at a time and live with the IP overhead.
That's why 8 kbps is the recommended more for 56 kbps modems.

        Jean-Marc


-- 
Jean-Marc Valin, M.Sc.A., ing. jr.
LABORIUS (http://www.gel.usherb.ca/laborius)
Université de Sherbrooke, Québec, Canada


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