Wirecast™
version 2.0
May 10, 2005
Hardware — FireWire (IEEE 1394)

FireWire is a hardware protocol that allows you to connect very highspeed devices (hard drives, cameras, etc) to your computer.

FireWire comes in two common "speeds": 400 mb/sec and 800 mb/sec.

FireWire Saturation

What you need to know about FireWire is that there is an absolute limit to the speed of your FireWire devices.

If you use a FireWire hub and plug several devices into that hub, you will share the bandwidth on that FireWire bus.

If the sum of your devices goes over the speed limit, you "saturate" (use up) the available speed.

If you have a camera attached to the FireWire bus and you saturate the bus, then you will see dropped frames (choppy video).

Devices do not always use all bandwidth

If you have a hard disk connected to a FireWire hub and also have your camera connected to the same hub, it may appear to work. You're using the camera just fine!

Unfortunately, this may not be a good indication of whether the bus will ever become saturated. For example, email could arrive and your email program could access a file on your FireWire drive which causes FireWire saturation.

The lesson to learn is this: Be careful when connecting hardware to your machine. Just because your setup works once when you first put it together in does not mean it will always work. Play with your setup and make sure that you have enough FireWire bandwidth to share all of your devices without experiencing choppy video.