multi_party_chat not consistent

[r s soni]

Hi,

please help me out.
I have setup easyrtc (latest) on LAN under same subnet.  I am using multiparty_chat demo for four persons.The problems i face are

1. sometimes all four video  not visible to all the four users.
2. few see only two while few see only three.
3. few see see only their own video and video containing boxex without video/audio for others <= this was tested on WAN at a distance of (800KM) remote user.
4. some times what ever videos are visible, the quality is not good.
   

reasons of such behaviour not understood.please suggest some solutions.

any help will be of tremendous importance.

rssoni

[Eric Davies]

Hi Rssoni,

Webrtc is cool stuff but what it can accomplished is limited by the physicals resources available to it. So, what can go wrong:

1. Insufficient resources on a machine: Webrtc compression and decompression isn't supported in hardware yet. Maintaining a 4 way call means that each party receiving packets from 3 other parties, AND decompressing the data in software. Most tablets are usually too underpowered to support more than a two way with any stability. If the video motion looks jerky in a 2-way call, a 4 way call is probably a pipe dream. Really old laptops and desktops, ditto.
   
2. Network bandwidth: each peer to peer connection has to send and receive a lot of packets. Can everybody's network sustain the traffic? Are there network devices in between that are trying to limit bandwidth? If the image quality diminish with more peer connections, then I'd blame your network bandwidth.
   
3. Firewalls and symmetric NATs: peer to peer connections through firewalls and routers rely on a technique called port busting. If Fred connects to a server through a router, that opens a temporary hole in the router, that another peer can use to send a packet back through. Not all Firewalls and routers allow this (particularly not security conscious corporate firewalls and routers) and  in that scenario you won't see any audio/video get through.

Experiment:

1. Have two people each open up two browsers windows (for a total of 4 browser windows) each pointing at your copy of the multiparty app. If that is successful, you'll know that those two people at least have sufficient cpu power. Do the same thing for the other two people.
   
2. Try www.speedtest.net to figure out what your upload speed is. Typically your download speed is faster than your upload so you don't need to worry about download speed. I think the usual figure is 50kbps for audio, 100 kbps for video, and that's per peer connection. If your problem is bandwidth, you can try reducing the video image size via a call to easyRTC.setVideoDims; a width of 320 and a height of 240 is usually supported by your webcam.
   
3. Try our tawk application at https://tawk.com. It uses a packet relaying server (aka, a TURN server) to get around those nasty Firewalls and routers. If it makes things work better for you, you just need to set up your own TURN server (there is an excellent one at https://code.google.com/p/rfc5766-turn-server/, and there are companies like viagenie that sell TURN as a service.