Jump to content

Transcoding


Snoop
 Share

Recommended Posts

We are running the SNOM One VMware Appliance and are having problems with transcoding. Our gateway uses g.729, but with the SNOM one license model we are only able to run 10x concurrent calls. Our extensions therefore have to use other codecs. Internal calls are fine, but the moment we attempt calling through the gateway the calls are garbled and nobody can hear anything. Changing the extensions to g.729 solves the problem, but we are then limited to 10x concurrent calls both internally and externally. We are using SNOM One Blue 4.5.0.1075.

Link to comment
Share on other sites

Transcoding always reduces call quality. Don't try to mix other low-rate codecs like GSM or G726 in, this will result in even worse quality.

 

VMware could be another risk factor. While it is possible to run the PBX in VMware glitch-free, AFAIK it requires some special resource assignments to make sure hat there is not another VM eating up CPU resources. When packets are garbled, it is very audible with G.729A while other codecs still sounds okay.

Link to comment
Share on other sites

Thanks for the reply.

 

1. Our gateway provider only supports g.729, so we can't use any other codecs.

2. My problem with the transcoding is that it doesn't work at all. Irrespective of load on the PBX or VMware server. When I load Snom ONE on a Windows server guest on the same VMware host it works, so there is definitely a problem with the appliance. I have experienced this with multiple sites I manage, so I am confident that the appliance is the issue. Is there a fix for it?

 

The problem with your 10 concurrent call limit and the inability to transcode means that all my calls (both internally and externally) are affected. If the transcoding can't be fixed I have to fork out for a Windows server license :-(

Link to comment
Share on other sites

Well... if your service provider supports only G.729A and you have only 10 G.729A licenses, then you can have only 10 calls. Workarounds with transcoding obviously causes significant challenges. That's why we added the a-la-cart item "calls" on V5.

 

But it should make any difference if you are using VMware or Windows. If that is any difference, it must be caused by the performance of the system.

Link to comment
Share on other sites

You misunderstand. The transcoding doesn't work at all when using the appliance. If I load a Windows server guest with Snom ONE on the same host the transcoding works. The problem with the 10 concurrent calls is that I have had to force my extensions to use g.729 as well in order to avoid the transcoding issue. I am therefore now limited to 10 concurrent internal calls as well. I can live with 10 concurrent trunk calls, because we only have 10 channels, but only having 10 concurrent internal calls is a massive problem.

Link to comment
Share on other sites

I think the problem is with CentOS. I have tried installing Snom ONE on my own CentOS VM guest and had the same problem. I suspect a timing issue, which is quite common in virtualization. Windows seems to manages it better then Linux. Transcoding is obviously very dependent on accurate timing, so it would make sense if this was the case.

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

 Share

×
×
  • Create New...