kichat: FAQ 5 Have You Enough Broadband Speed For iChat ?

Have You Enough Broadband Speed For iChatAV 2.x ?
(Panther iChat FAQ)

Hi,

Symptoms
Choppy or pixelated video is usually related to insufficient broadband speed. Other symptoms that may also be linked to this are chats where one element is missing, including sound in both directions but video in only one. It is possible that you are experiencing the "dropping out" of one element during a chat. You should test the speed of your connection to the internet

Action
You can use this Speed Test. You can use this Broadband Speed Test if the first one is too busy.

Do the tests. Do not just assume that you are getting the promised speed from your DSL or Cable ISP. Broadband speed promised is not always what is delivered.

Both uplink and downlink speeds effect the connection, as do the speeds for each party to the connection. To remove doubt about speed, BOTH you and the ones with whom you experience the problem with should use the Speed Test with at least two of the servers regardless of which test site you use.

Info Mac to Mac
The lowest speed that iChat will work is 50kbps. Below this figure, iChat will give you an error message about the lack of speed and not complete the call.
You should get smooth Mac<-> Mac video if all uplink and downlink speeds for both ends of the connection is above 99 Kbps. ('real' world speeds, as measured by the test not as reported by the Connection Doctor)
If ALL your numbers are well above that, you can probably safely assume that connection speed is NOT causing your pixelated video.

Mac <-> Mac connection speeds can be in the 80-100 Kbps range and still work reliably, though quality will decrease. Of course, more speed (up to about about 500 Kbps) gives better results. Beyond 500 Kbps, more speed seems to make little difference in my experience.

Info Mac to PC
Mac <-> PC video needs higher connection speeds, at least 150Kbps for smooth video. I have connected with PCs as low as the 110-120 Kbps range, but the video is poor quality, pixelated, and unstable.
Do not forget the PC end may well (Most likely) be using a USB camera. The quality may not be as good as your Firewire camera and it will take processing power at the PC end.

What to do About it
Using the data you gather with Speed Test, if either of your ISPs are NOT delivering what you are paying for in your service billing, you will have FACTS to use to get resolution.
If the speed IS all that is advertised but it is below the recommended minimums, you may want to upgrade your service to get better video between Mac and PC.
Only you can decide whether spending money for a higher bandwidth service is worthwhile.

These numbers assume you have only one computer on the connection. If you have more than one computer sharing the connection, you will need the above bandwidth for each; i.e., if you have 2 computers using the connection simultaneously, multiply the requirements by 2 to be sure speed is not your problem.

If your test indicates that speed is not the problem, post back your speed numbers and details of how you connect your Macs to your DSL ISP. (Make and Model of your modems, routers, and wireless equipment as well as how many computers share each of your connection.) In some cases the country you are talking from and to would be helpful.

Written By EZ Jim and Edited by Ralph Johns

Edit 5/5/05 iChat 3 info will follow soon. See This Apple Doc