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[Question #219552]: rohc 1.5.1 does not compress VoIP


New question #219552 on rohc:

Hello team, 

I am using rohc 1.5.1 on 2 servers Centos 4.x and 5.x.
I installed from sources following your wiki and tunnel is up with data transfer OK.

It seems to be working fine but I need rohc to compress RTP flow, so I set up a tunnel on 2 asterisks and created a sip trunk in this rohc tunnel.

Here is the command I use:
/opt/rohc/sbin/rohctunnel rohc0 remote "public ip 1" local  port 5000 3> /opt/rohc/comp_stats 4> /opt/rohc/decomp_stats &
/opt/rohc/sbin/rohctunnel rohc0 remote "public ip 2" local "public ip 1" port 5000 3> /opt/rohc/comp_stats 4> /opt/rohc/decomp_stats &
I use local IP on server 1 because it is behind a router.

It is up and sip calls (g729) connect.

However, I need to verify rohc's compression rate.
Thus, I used 2 different tools to monitore bandwidth: iftop and a router calculating BP stats.

My problem is that a call going through rohc takes as much BP as a non compressed one (about 30kb/s).
I tried up to 3 calls and no difference were noticed.

Compression logs  during call shows that it is working:
206     O-mode  SO      60      28      36      4       0

FYI, asterisk trunks are set with "canreinvite=no" to be sure that RTP goes through the tunnel and not directly to the public IP.

Does anyone have an idea?

Thanks in advance

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