Video call QoS

[Dieselboy]

I had a weird issue the other week where the video calls were doing weird things. Audio was perfect and clear. Video however would artifact suggesting packet loss. But it would do it in such a way that at one point, the person I was speaking to had no face. Everything else was clear such as the room, the wall, his body head and other things like hair, but his entire face was just skin colour, like it was his back or something. 

Anyway, I found that the video phones were tagging audio and video packets with the same qos value of AF41. I thought this was odd, and was expecting voice to be EF tagged. But in short, this is by design so that voice and video packets receive the same qos to arrive at the destination at the same time else the risk is out of sync voice and video.

The video issue was the access switch policing AF41 to 500kbps, but why this was not affecting the audio whatsoever I don't know. I didn't check the call stats so not sure if there was slight loss. I'm using g711 though.  I ended up doing away with (caugh) autoqos SRND4 for the video endpoints and designing my own. The challenge was to prioritise jabber softphones as well as video endpoints.

posting here as reference.

[deanwebb]

Losing the face suggests that that's the only part of the video stream going out and it's taking a page from animated gifs - keep size small by only updating the part of the image where the action is.

Audio is arguably the more important part of the call, so maybe it goes through because someone decided the audio should always get through in a business call.