Friday, July 15, 2011

Reducing the bandwidth requirements of web conferences

The use of web conferencing (that is video conferences using web based software) is becoming more common. Recently I have been taking part in video conferences using "Blackboard Collaborate" (previously called Elluminate Live!"). When used in my office with a high speed cable connection it works fine with the default settings. But when using my slower (and higher latency) wireless mobile modem, there are delays. This can be fixed by changing the settings in the conference software (the place where this is set differs amongst products, but they all do much the same thing):
  1. Set the maximum bandwidth to dial-up speed: Collaborate has a minimum setting of 28.8 kbps. While slow by broadband speeds, this is still fast enough for two way audio, a small video window and slides. Even if your link has a higher theoretical speed, it may be worth setting this lower to allow a slow PC to keep up.
  2. Set the video to a few frames per second: Collaborate has a minimum setting of 1 frame per second. This is sufficient to give the sense of someone being there. Particularly if you are not the main speaker, this should do. You can also make the image lower resolution. It also helps to set the system to automatically highlight the video of the current speaker, so you know who is talking.
  3. Set the audio to 8,000 Hz: By default the audio for conferences will be set higher than standard telephone quality audio (8,000 Hz). Unless you are conducting music lessons, setting this to telephone quality should be fine. This setting might improve the quality of the audio in some settings, as it will reject noise not in the range of the human voice.
  4. Set push to talk, with half duplex sound: By default the audio should be set so that you have to push a button to be heard. This prevents stray room sounds disturbing the participants and saves on bandwidth. Also setting half duplex helps with clarity: that is when your microphone is turned on, your speakers are turned off: you cannot talk and hear at the same time. People have to take turns to speak, which works well for large groups.

1 comment:

Rupert Uriza said...

Thanks, Tom! This is a great resource!