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

[w4]

hi,

thanks for the suggestions. i tried the G729b directly and indeed this
is the only codec where i could see a kind of VAD/DTX. wireshark shows
fewer packets in silence periods (actually it shows STUN packets...?)

would be great to know why i don't see any DTX with other codecs as also
the suggested PCMU shows a continuous flow in wireshark. i first thought
that maybe my mic isn't muted properly. but since all codecs send
silence (for instance PCMU uses ff:ff:ff...) and also with other UA i
can reproduce a visible VAD behavior, i begin to doubt that i am doing
it wrong...

opus seems to ignore usedtx=1 as well. is it btw possible to use opus
with a constant bit rate? (cbr=on?)...

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

sorry, it was old-stable (wheezy) with version 3.5.2...

the last tests i did with two new git clones.

if somebody has the time to produce a wireshark capture with activated
VAD for speex or pcmu... ;)

best,
Anne

On 10.08.2016 23:32, Johan Pascal wrote:
> 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
>>>>
>>>>
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>>>
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