[Freeswitch-users] Can not see video with low internet connection (audio is ok)

Claus Andersen clan at wheel.dk
Thu Oct 9 13:14:30 MSD 2014


On Thu, 9 Oct 2014, To Hai Son wrote:

> Video calls are performed perfectly with high speed internet connection, but if internet connection speed is
> quite low, we can not see the video, just can hear voice only. We have make an emulation call from PC with low
> speed of internet connection, the same problem occurred.

You are not giving a lot of factual information here. What codecs are you 
using? What resolution and framerate did you expect. How is your call 
setup (transcoding etc.)? What is "low" speed.

H.264 will only consume around 10 kbps with around 2 fps in 176x144. That 
is very low quality - but it is better than nothing.

It could be the endpoint deciding that the bandwidth is too low and then 
prioritize the audio and sends no video (nor offers it). What are your end 

Is video even viable in your "low bandwidth" scenario?

> We guess that there is a parameter in FreeSwitch to limit the internet connection, and server does not allow
> video stream if internet connection speed is lower than this parameter. We are newbie to Freeswitch, we do not
> know much about it, so please help us.

If you are completely new to Freeswitch then I would start by examining 
your traffic flow. Are you sure that the video streams flow through 


> Any advice will be appreciated.

My advice would be:
- Examine the SIP call flow
- Examine the SDP to determine if video has been agreed upon
- Examine the RTP stream path
- Check call setup log on client (which could be the one throttling!)
- Examine Proxy Media and Bypass media (does Freeswitch even interfere?)
- Look what happens during call setup: 

I would spend the most time looking at the logs on the end-points. What 
codecs where negotiated and is video even sent?

In all logs I would pay paticular attention to the results of of the SIP 
INVITE and the SDPs. The SDP will tell you what options are offered and 

Kind Regards,
Claus Andersen

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