Re: [Linphone-developers] DTX / VAD for Speex in linphone

[Johan Pascal]

Hi,

linphone provides VAD/DTX/CNG for PCMU using the bcg729 library, you 
must for that turn on ENABLE_G729_CNG at build(latest source code only). 
If it is just for test purposes and do not care about the codec itself, 
you can directly use G729 annexB(you must also use a recent source code 
to get annexB in bcg729) which shall give you clear patterns of very 
small and fewer packets during silence period.

I have no idea about how speex manages VAD/DTX actually, but it looks 
strange to get the same amount of packets during speech or silence but 
your INVITE and OK seems fine.

Linphone on debian stable is version 3.6.1 and provides opus codec: 
https://packages.debian.org/jessie/linphone

regards,


johan

On 09/08/16 11:48, address@hidden wrote:
> Ok,
>
> good to know that there should be fewer packets. Then my configuration
> must be faulty...Anyway, i can't see nothing wrong in the SDP INVITE or
> OK response...
>
> INVITE part (Linphone/3.9.1 (belle-sip/1.4.2) git version on Kali linux)
>
> v=0
> o=linphone 3447 4091 IN IP4 yyy.yyy.yyy.yyy
> s=Talk
> c=IN IP4 yyy.yyy.yyy.yyy
> t=0 0
> a=rtcp-xr:rcvr-rtt=all:10000 stat-summary=loss,dup,jitt,TTL voip-metrics
> m=audio 7078 RTP/AVP 96 101
> a=rtpmap:96 speex/8000
> a=fmtp:96 vad=on
> a=rtpmap:101 telephone-event/8000
> a=rtcp-fb:* trr-int 5
>
>
> OK response part...(Linphone/3.5.2 (eXosip2/3.6.0) repository version on
> debian stable - no opus here btw (?))
>
> v=0
> o=linphonetoo 3636 3636 IN IP4 xxx.xxx.xxx.xxx
> s=Talk
> c=IN IP4 xxx.xxx.xxx.xxx
> t=0 0
> m=audio 7078 RTP/AVP 96 101
> a=rtpmap:96 speex/8000
> a=fmtp:96 vad=on
> a=rtpmap:101 telephone-event/8000
> a=fmtp:101 0-11
>
> I don't have to use Speex (it was simply the codec i tested first).
>
> BTW, Does Linphone offer some kind of generic VAD for codecs which don't
> have it built-in, like PCMA/U?
>
> My purpose is to do some research on VAD-related attack vectors, but
> without VAD/DTX i can't do testing, so yes, i would really like to turn
> it on ;)
>
> Best,
> Anne
>
>
>
>
>
>
> On 08.08.2016 22:41, Johan Pascal wrote:
> > Hi,
> >
> > speex codec directly manages the VAD/DTX as long as you use vbr=on or
> > vbr=vad in your fmtp parameter, can you check these parameter is
> > correctly set in the SDP INVITE and peer response to the invite ? During
> > silence you shall have fewer and smaller packets.
> >
> > By the way, speex is now superseded by opus, why do you need to use speex?
> >
> > regards,
> >
> > johan
> >
> >
> > On 08/08/16 17:41, address@hidden wrote:
> > > Hi list,
> > >
> > > I don't know if developers are on the users list as well, so i would
> > > like to ask almost the same question here again and i hope you don't
> > > hold it against me:
> > >
> > > I am trying to get VAD working in linphone, but i fail. Or maybe i
> > > misunderstood the concept?
> > >
> > > When i try to activate VAD (vbr=vad, vad=on) for Speex in the linphonerc
> > > speech pauses don't result in fewer packets being sent. Only the RTP
> > > payload is smaller during silence. Is this already VAD? Then i am
> > > missing DTX i guess?
> > >
> > > So, is there any possibility to use DTX in linphone, ideally together
> > > with VAD?
> > >
> > > Best,
> > > Anne
> > >
> > >
> > > _______________________________________________
> > > Linphone-developers mailing list
> > > address@hidden
> > > https://lists.nongnu.org/mailman/listinfo/linphone-developers
> >
> > _______________________________________________
> > Linphone-developers mailing list
> > address@hidden
> > https://lists.nongnu.org/mailman/listinfo/linphone-developers
> _______________________________________________
> Linphone-developers mailing list
> address@hidden
> https://lists.nongnu.org/mailman/listinfo/linphone-developers