Optimizing iChat

Question

I had iChat working really well under Leopard 10.5.8 - perfectly, in fact. I hadn't used iChat since upgrading to a new iMac and Snow Leopard 10.6.3 until yesterday and I noticed that the incoming video was really breaking up and pixelated - very jumpy and jerky (the person I was chatting with had no such problem on their end - I was coming in perfectly for them). I have my iChat version 5.0.3 bandwidth limit set to 500 and previously had streaming set to 1.5 in QuickTime settings but there are no QT settings in Mac OS X 10.6.3. Any idea what may be causing this? I've read that some people recommend setting the bandwidth limit to 200 but that's where I get confused. Shouldn't a higher bandwidth work better - or perhaps, automatic?

Answer 1

Hi Gerard,
Yes, the lack of the Quicktime Setting can cause some people issues.
Since iChat 2 iChat read the Quicktime Streaming speed.
However it could not read the Automatic setting as an open setting. It interpreted it as a figure which was sometimes written to the com.apple.ichat.plist as a zero.
In iChat 4 this was set to be read as 384kbps which meant in theory anyone could host a 4 way Video chat.
In OS 10.3.x and 10.4.x (for iChat 2 and 3) the Streaming Intranet/LAN setting also returned an unreadable figure to iChat and so the 1.5Mbps T1/Intranet/LAN setting became the de facto setting to use.
This made sure iChat could use as much of your Internet speed as it could see.
During this time most cable and DSL connection speeds have seen a leap from about 128kbps Upload speeds to an average of closer to a 1Mbps uploads with downloads being much faster as well.
This in turn meant that although the 1.5Mbps may have exceeded your Upload Speed it also capped everyone to a similar speed if they were faster than that.
iChat 5 can see your whole Internet Connection speed (Upload being the limiting factor)
This means that between two buddies at any one time you may have a much greater speed difference.
ichat is supposed to negotiate between the two Buddies on a common speed and the Buffering in iChat is supposed to take care of the variances in that speed.
The issue with that is that a 5% difference in a 20Mbps service is vastly greater than anything iChat was trying to buffer before, hence blocky Video, Audio Drop outs and strange pixelisation.
The only way to control this now is to limit iChat in the Bandwidth setting as you have read.
It is best done on both ends to aim to be as close as possible.
We are currently recommending using the 500kbps as the first choice and if you still have problems try 200kbps.
AS the other poster has said it pays to check with several Buddies so that you get the "best for all your Buddies" setting that you can (with the occasional tweak for some "Special Cases").
Summary.
The previous methods of setting up iChat kept the Bandwidth (portion of Internet speed) to a closer average for everyone.
In iChat 5 to enable the Buffering to cope with speed Variances, use the Bandwidth Limit setting, starting with 500kbps.
7:20 PM Thursday; June 10, 2010
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