[Asterisk-Dev] changing codec during call

[alex at pilosoft.com]

On Fri, 25 Feb 2005, Race Vanderdecken wrote:

> The "jitter buffer" is used, and I might be wrong on the details of
> asterisk, to overlap information so that if a sound bite is lost it can
> make up the missing buffer from the extra information in the preceding
> and following buffers.
No, you are describing FEC.

Jitter buffering is intentionally delaying output stream by x ms, where x 
is the maximal expected jitter.


> If an event that damages packets happens once a second then any packet
> over a second with be damaged and have to be resent, but the smaller the
> packet the less chance it has of being damaged. And if it is damaged
> then less information is lost, so the error correction can be smaller.
> That is why the 1500 byte frames work better then 150,000 byte frames.
> The odds are just better. (yes, the math is simple, but you get the
> idea. Flame only if you have a good math example.)
You have absolutely no clue what you are talking about.

> Also, asterisk is a bad example of a RTP conversation protocol users. A
> human conversation is silence 1/3 of the time, and half duplex
> communication the other 2/3's.  I talk, silence, you talk, silence, I,
> silence, then you and so one. So in a real system the bandwidth is
> mostly empty. Most of the time. During a full duplex conversation the
> path from me to you is silence 2/3rds of the time, and with compression,
> the actual audio data of value is probably on sucking up about 1/6 of
> the bandwidth at a time. That is why compression works, most of the
> audio is just dead air where you can squeeze in another conversation.
> The 80K rule is when both of you are playing background music and
> talking without listening to each to each other. Voice is not data, even
> when it is converted to digital. (Please being you ranting now.)
> 
> Race "The Tyrant" Vandedecken
Mr Tyrant,

Can you please tyrannize something else other than asterisk-dev? I haven't
seen an intelligent post from you here yet.


-alex