G.729 codec bad quality

[Toulousaing]

Hi all,

I'm having trouble with G.729 codec. Here is the problem: few minutes after conversation has started, one Obi end (sometimes both) starts hearing degraded voice (rough and low).
But for the first minutes, it's crystal clear so it' just a pity. One important factor is that one end is using low bandwith (256k) connection.

Do you know where I should look at or have you ever experienced such issue?

Cheers

[Edit] I'm using G.729 for its low bandwith usage, but I think Obihai should consider implementing G.723.1 (best for such use case). Meanwhile, I'm stuck with G.726-16

[Stewart]

First, are you using G.729 to avoid high data usage charges or a low cap?  Otherwise, there must be some technical problem, because 256 kbps is enough for two concurrent G.711 calls!

I suspect that there may be a problem with data buffering in the router or modem, or perhaps a timing issue.  Test each end separately, using a provider that supports G.729 (and check Call Status to confirm that it is being used).  A free Callcentric account should suffice for this purpose, calling in via SIPBroker or iNum, or calling out to a toll-free via SIPBroker.

If both ends are ok when tested separately, try calling via Callcentric, rather than directly between the devices.

[Toulousaing]

Hi Stewart, thanks for your prompt reply 
I was quite busy these last days, but yesterday I've tried one thing that solved the issue!
Even though your post didn't give the solution, it was very inspiring as it made think of some kind of incompatibility between router and Obi devices.

So, I went from 10 mb/s to to 100 mb/s full-duplex on both ends, using procedure laid down here:
http://www.obitalk.com/forum/index.php?topic=2642.0

Obi is amazing
Obitalk community is magic

[ianobi]

Hi Toulousaing, I agree with your last two comments 

Interestingly, "Option 27" remains undocumented except for here in this forum. I wonder if Options 28 and 29  do anything of use to us all? Perhaps Obihai like to leave a few mysteries to keep our community on our toes 

[OZOi]

Interesting. Why setting to 100 mb/s full duplex helps to resolve the problem of degrading voice quality with G.729 after a couple of minutes of use? Frankly I don't see any connections between those two...

And is setting option 27 permanent? Does it survive the reboot? What about changing and/or restoring configuration?

BTW, I wish OBi has included more low bit rate codecs - for example, SILK, iLBC (both are free and provide excellent voice quality with phones, that have limited bandwidth).

[Ostracus]

iLBC is on the Obi202.

[OZOi]

Good to know that
But what about OBi100? We need that too

And it would be very nice to have SILK codec. I'm currently use it from Android phone to connect to SIP switch. I think it's the best if you have low bandwidth environment. It's smooth and recovers very well from lost packets (which may occur quite often under this condition). Unfortunately I can't use it with calls to/from OBi100 though - currently it lacks of SILK support...  I guess SILK will be used more and more, since Microsoft has bought Skype and is going to include it into their OS...

[ianobi]

Option 27 seems to survive reboots following configuration changes for me on my OBi110. I cannot say if it survives a restore.

[OZOi]

Thank you, ianobi!