If like me you've got a camcorder with a firewire port you are probably thinking it would be cool to connect to your PC via a USB port. Many laptops don't come with Firewire ports so USB would be far more convenient. Surely there must be a cable to do this?
But beware. Although you can buy "Firewire to USB" cables they will not work with most camcorders. They simply wire the firewire connections to the USB pins. Nothing more.
Firewire and USB are data protocols. They are very different. Firewire data looks nothing like USB data so a USB port on a PC or laptop can not understand a stream of data from a Firewire device. It doesn't matter how you wire it up they are not compatible. The PC will simply not see a USB device connected and will do nothing.
It is nothing to do with quality. I've heard people say "it might work with reduced quality". That is wrong. The PC either connects to the device and accepts the data or it doesn't. It is like connecting composite video to an optical audio socket.
So why do they sell the cables? Surely they must work?
They sell the cables for two reasons. For starters people keep buying them so they keep selling them. The second reason is that some camcorders are clever enough to know what port you have connected the camera to. If it detects a Firewire port it kicks out Firewire encoded data like normal. If it detects a USB port it will switch to USB encoded data.
The PC sees the device as a USB device rather than a Firewire device and is happy.
THIS IS DEPENDENT ON THE CAMCORDER. If your camcorder doesn't mention this feature in the user manual then it probably doesn't do it.
Don't waste your money on these cables as there is a good chance they won't work. "They are only a few dollars/pounds/euros" I hear you say. "It's worth the risk". It's your money but you are going to end up with yet another cable in your desk drawer that you will never use!