[Telepathy] change speexenc settings for empathy

[Olivier Crête]

On Sat, 2011-04-09 at 10:05 +0200, Alexey Fisher wrote:
> Am Freitag, den 08.04.2011, 21:57 +0200 schrieb Alexey Fisher:
> > Am Freitag, den 08.04.2011, 12:16 -0400 schrieb Olivier Crête:
> > > On Fri, 2011-04-08 at 17:57 +0200, Alexey Fisher wrote:
> > > > Hi
> > > > Am Freitag, den 08.04.2011, 11:42 -0400 schrieb Olivier Crête:
> > > > > > dtx=1
> > > > > > # do not send any packets on silence
> > > > > > # see Bug https://bugzilla.gnome.org/show_bug.cgi?id=646474
> > > > > 
> > > > > This gives you the impression that the bitrate is lower because you
> > > > > don't send why not speaking. But it doesn't change the maximum bitrate
> > > > > (when speaking) which is all that really matters for quality..
> > > > >
> > > > > It will also break if WMM is enabled, in that case, the wireless router
> > > > > only sends out frames when it receives one, so you have to send
> > > > > continuously to keep on receiving.
> > > > 
> > > > My fault in description. It send about 2 packets/sec to keep connection.
> > > 
> > > That's not enough.. You won't get incoming packets unless you send
> > > outgoing packets.. so if you send 2 packets per second, it means you
> > > only get incoming packets twice per second, which will destroy your
> > > audio.
> > > 
> > > Unless someone tells me there is a reliable way to temporarily disable
> > > WMM from an application, DTX is not usable with WiFi networks.
> > 
> > Hmm, i'm confused.
> > if i understand correctly, the behavior like: 2 packets send / 2 packets
> > receive can be caused by firewall.
> 
> I digget i bit deeper in the firwall issue. It called "NAT traversal" or
> "UDP hole punching". TO keep the hole in firewall/nat we need only send
> empty udp packet.
> 
> So this will still reduce the traffic, but also keep as possible to keep
> connection open. This is mach better then doing that what we do now.

If you care about NAT traversal, libnice already does the stuff for us..

> > WMM is completely  different. WMM make sense only on the air, between AP
> > and client. If AP was configured correctly (my dd-wrt seems not
> > configured at all), it will map DSCP numbers to WMM (0x18->BE; 0x10->
> > BG; 0x28->VI; 0x38-> VO). Empathy do not set DSCP, Skype do not do it
> > too. It seems like some/all ISP ignore DSCP or reset it to 0. So WMM or
> > DSCP do not make any difference.

The power management behavior with WMM (called WMM Power Save) is that
the Client tries to keep its radio off for as long as possible. So it's
not on at all times to wait for incoming packets. It only gets packets
in two cases, the first is every X milliseconds (where X is too large
for VoIP traffic), it wakes up and asks the AP if it has any packets for
it. The second case is that after sending a packet, the AP has a chance
to send any packets the other way.

So the way to keep on receiving data it to send out packets
continuously, even if there is no actual data to be sent. It does waste
bandwidth, but for now it's the best we can do.. Unless someone can
figure out a way to reliably disable it while in a call.

-- 
Olivier Crête
olivier.crete at collabora.co.uk
Collabora Ltd
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