iSight questions

krollster

macrumors member
Original poster
Jul 24, 2002
61
0
London
I have a few questions about using an iSight that I'm hoping someone might be able to help me with. I'm in the UK and want to talk to people back in Australia. We've both got 256k broadband connections. The questions are as follows:

1. Is a 256 kbps connection likely to be fast enought for smooth video?
2. How much data does an iSight use when engaging in a two-way video conversation?

The reasons for the second question is that the data allocations in Aus are not that generous on the cheaper plans, and we'd like to be sure that they'll have enough for all their needs (chatting and surfing predominantly).

Thanks in advance :cool:
 

frenetic

macrumors regular
Feb 11, 2004
226
27
Amsterdam
My girlfriend lives in Peru, and she has a 600/128 kbps connection. The video chat is quite ok - not pristine, but ok. The important thing to keep in mind is your upload speed, anything lower than 128 kbps will not work, I think.
 
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krollster

macrumors member
Original poster
Jul 24, 2002
61
0
London
frenetic said:
My girlfriend lives in Peru, and she has a 600/128 kbps connection. The video chat is quite ok - not pristine, but ok. The important thing to keep in mind is your upload speed, anything lower than 128 kbps will not work, I think.
Good point Frenetic, the upload speed would have a big impact on the quality. Any idea about how much data the thing uses?
 
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frenetic

macrumors regular
Feb 11, 2004
226
27
Amsterdam
krollster said:
Good point Frenetic, the upload speed would have a big impact on the quality. Any idea about how much data the thing uses?
Both of our isights are put on 500 kbps in ichat, but I don't know how much it actually uses. I'll talk with her later on during the day, and I will check with the connection doctor how much it uses, and post it back here.
 
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emw

macrumors G4
Aug 2, 2004
11,177
0
krollster said:
Good point Frenetic, the upload speed would have a big impact on the quality. Any idea about how much data the thing uses?
What frenetic is referring to, I believe, is the bandwidth limits you can assign to video transmissions in iChat's preferences. See a small screen grab below...
 

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Zenith

macrumors 6502
May 18, 2001
300
0
Norway
I have noticed that a 640kbps upload seems to be required to be able to send video in highest quality. Anything less than that will provide video with noticeably worse, but good, quality. The upload speed of your connection is all that counts, and a 128k upload would work out good enough, but 512k would be far better. When going from 512k to 640k, if you have a powerful CPU, the resolution of the video doubles and it looks much better.

With the current encoding of Panther and iChat v2 a slower bandwidth will result in "squared" video with parts of the image lagging behind when high speed or moving elements appear. This works much better with the new codec in Tiger, Quicktime 7 and iChat v3, H.264. I have seen it and tested it, and it's much better than iChat v2.

I have also discovered that when using iChat and two iSights on two different Macs on a LAN they don't utilize more than 250-260 kBps (2000kbit). So that is apparently the maximum of bandwidth it will use on any kind of connection. The video from the remote computer then looked like it came unprocessed straight from the iSight.
 
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frenetic

macrumors regular
Feb 11, 2004
226
27
Amsterdam
ok, these are the data I got from the connection doctor:

Remote:
Frame rate: 14.5 fps
Bit rate: 82.6 kbps

Local:
Frame rate: 30
Bit rate: 400

So I guess that with a 128 kbps upload speed you should be able to get it to work.
 
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krollster

macrumors member
Original poster
Jul 24, 2002
61
0
London
Thanks

Thanks for the info. I think I'll have to look into it a bit more before I fork out 100 squid to get an iSight.
 
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dotdotdot

macrumors 68020
Jan 23, 2005
2,381
33
Thats good - my internet is odd... 800kbps + Upload speeds, 300kbps+ download speeds... yes, I didn't confuse up/dl. Its odd, ain't it?
 
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frenetic

macrumors regular
Feb 11, 2004
226
27
Amsterdam
dotdotdot said:
Thats good - my internet is odd... 800kbps + Upload speeds, 300kbps+ download speeds... yes, I didn't confuse up/dl. Its odd, ain't it?
That is very bizarre indeed, I have never heard of an ISP that offers a faster upload than download.
 
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