Afternoon all,

We are going through a few codecs.  One sounds too "tinny" to some users and the other cuts out and gives the "robot voice" sound during peak call/data traffic times.  We are using G.729ab right now and our vendor usually uses G.722.  Which is what we just changed off of.  Anyone have any recommendations? We do get periodic jitter, but nothing major.

Thanks
  

G.729 is pretty much a good, all around codec to use. It compresses 64 kpbs to 8 kbps plus overhead. I have heard that G.726 only compresses to 16 kbps plus overhead. Apparently the Mitel 5000 can use the G.726, for a coworker set their compression to that I believe.

Besides codec, you need to test latency, for latency of more than 150ms can cause negative issues.

"If I had known it would turn out like this, I would have became a locksmith" Albert Einstein

NCSS  NCTS  NCTE CS1000E
Mitel 3300 4.2 basic & advanced, 5000 4.0, NuPoint I&M 4.2
 

g.722 is only available on rel 5.0+ and then only on high end sets
5330, 5340 & 5360
The sets will auto negotiate g.722 if the are on non compressed routes or local with each other.
g.722 is HQ audio some people do not like it as it is like digital radio and can be disconcerting at first as it is noticeably different.
g.711 is default and is the standard telephone voice quality
g.729 is the same as g.711 however some people can detect a slight difference in quality.

As for a jitter tolerent codec g.711 will be less noticable than g.722
 

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Just to add, the 'best' codec depends on your use-case.  

G722.1 provides wideband, so it is the best of the three for music.  Mics and speakers however can cause it to sound a bit tinny for some though (myself included).

G729 is very close to G711 for normal audio, and it has some better packet loss compensation handling built-in over G711, however it's geared towards human voice, so features such as music on hold will sound less than optimal.

For overall use G711 is the best of the three.  You just need the bandwidth and the network to handle it.

Thanks all - appreciate the help.  It's using G711 now - since the tech swapped it, and when we have network congestion you can really notice it.  You can really tell G711 hogs more, it's either "tinny" on the more efficient codec, or breaking up due to the network congestion.  We have minimum jitter - no packet loss too.

Very frustrating..


 

Regardless of the codec, you should separate your voice and data on vlans.  'Network congestion' will affect all of them equally.

But I'm missing something, you say you have network congestion, yet minimum jitter and no packet loss.  To me, network congestion == jitter.
 

His jitter buffer could have been set too low...

Jim

"If I had known it would turn out like this, I would have became a locksmith" Albert Einstein

NCSS  NCTS  NCTE CS1000E
Mitel 3300 4.2 basic & advanced, 5000 4.0, NuPoint I&M 4.2
 

That could be it - I know the vendor didn't change much of the defaults, is there a command line to set and/or check the jitter setting threshold?  I can check that next.  Our network is separated into vlans - voice/data with Voice QOS over data - as priority and lvl 6 set.  

Thx all.

Jitter buffers in the system (controller and sets), to my knowledge are not configurable, they can handle a max of 800ms.  They are dynamic, meaning you don't have to 'set' them.

Can you describe what you mean by 'network congestion'?