All computers and camcorders (as well as most pieces of electronic equipment) have what are known as ports. The purpose of a port is to act as a means of transmitting information from one source to another. For example, when you connect a camcorder to a television to watch the video, you are running a composite (also called RCA) cable from the camcorder's composite-out port to the television's composite-in port.
In connecting a camcorder to a computer, you have at the present three basic scenarios.
Firewire has become the de facto standard for transferring digital video from the camcorder to the computer and back again. The firewire standard was developed by Apple computer in 1985, and has achieved status with the Institute of Electrical and Electronics Engineers under the standard of IEEE-1394. It is also known i.Link on Sony products or just as "DV", short for Digitial video, on other models. All these terms refer to the same thing.
The basic procedure for connecting a camcorder to a computer with a firewire port is simple. Make sure your camcorder is running on AC power (ie., plugged into an outlet), and leave it off. Connect one end of the firewire cable to the camcorder's DV port, and the other end to the firewire port on the computer. When the computer is on, turn on the camcorder. The computer should automatically recognize the camcorder.
Firewire is rightly promoted as having a bandwidth of 400 megabits per second; however, digital video being transferred from the camcorder uses very little of this bandwidth and you will still be capturing video in real-time. That is, if you want to transfer an hour of digital video to your computer, it will take an hour to transfer.
2. Analog video capture
If your camcorder doesn't have a firewire port, or you for whatever reason you can't or don't want to use firewire, you have the option of capturing the analog video signal that comes out of the composite or S-video ports and digitizing it into a signal readable by the computer. There are a number of products out there that support this functionality, and many people claim that video captured with an analog process is actually better to work with for certain functions such as bluescreening. For the average home user however, firewire capture is much simpler and much less frustrating.
Analog video capture works by transforming the analog video signal with a hardware device into a digital signal that can be saved on computer. Raw, uncompressed video takes up a lot of space, so it's compressed with a codec to make it easier to work with. Most of these devices use MJPEG (motion-JPEG) compression, but it is possible with some to use your own codecs, reduce frame rate, resolution or frame size, in order to save space. In this regard analog video capture is much more flexible than firewire capture; with firewire, you must capture at the standard 720x480 / 29.97 fps combination, which means your file sizes will be quite large and there's nothing you can do about it.
Unfortunately, the success of analog video capture depends heavily on the stability and speed of your computer system. If you don't have a stable and/or fast system, the video signal will not be transformed fast enough into digital, and you will drop frames. The frustrating part of analog video capture is that there are many variables which affect speed and stability, so even users with 800 mhz machines can see dropped frames and not be able to figure out how to fix it. With firewire capture, dropped frames are comparatively rare.
3. USB capture
More and more camcorders are coming equipped with a USB port. The only reason a USB port exists on a camcorder is to transfer still pictures, not video. The simple fact is that at the moment, USB doesn't have enough bandwidth to transfer digital video.
Last update: 09:40 PM Wednesday, November 21, 2007