[SR-Users] (no subject)

[Richard Fuchs]

On 10/29/14 10:08, Yuriy Gorlichenko wrote:
> Hello. I use kamailio with last rtpengine and 
> I have 5-7 Seconds voice delay. This happened only for  from webphone.
> But it is not client issue as i see. Wireshark at client side shows that
> RTP starts as soon I pick up call. So rtp leaves rtpengine and goes to
> the destination with delay... I use WSS and think that problem at
> handshake. 
> 
> There are some statisticcs after call finished (as example). You may see
> that one of streams created after 5 seconds delay.

The difference in the times you posted is the delay between the offer
and the answer, e.g. between INVITE and 200 OK. This is normal if you're
slow to pick up the call. As for audio delay, some clients/browsers
(Firefox especially I believe) are slow with starting or responding to
the DTLS handshake. Since the SRTP encryption keys are negotiated during
the DTLS handshake, no SRTP can be sent until after this has been
completed. You can see this in the log. If you run a packet dump, what
you will normally see is that rtpengine starts the DTLS handshake right
away, but the browser doesn't respond until several seconds after. I'm
not sure why they do this.

cheers