What Are External Analog Capture Cards Used For?
An external analog card allows you to view video from a composite setup or S-Video on your computer and record the data coming through it. Since the device connects to the computer using a peripheral universal serial bus — USB — cable, you don't have to open your computer and install the capture device with fears of messing up your computer's innerds .
The fact the device is external also makes the device portable, so it's possible for you to transport it from one computer to another without having to mess around much. This comes useful if you have a laptop and go from place to place rather frequently.
Some capture cards come with an HDMI output to relay video to a TV. This feature comes in handy when you want to present the video to others through a larger and more comfortably situated screen. Every feature counts when you want to get a video capture card that you don't intend to replace later on.
If you want to decode a TV signal coming from an antenna, make sure you buy a video capture card with an integrated TV tuner. These cards have a coaxial cable port that allows you to connect a standard TV cable to the device. Research the type of signal your TV tuner decodes, or you might end up disappointed! If you only want to decode analog TV signals, stay away from video capture cards that advertise DVB-T decoding unless they also advertise analog capabilities.
Some larger-resolution models might use FireWire or USB 3.0. Be aware that your computer won't process video at a high frame rate if you use a USB 3.0 capture device on a USB 2.0 port. Some capture devices come with an ultra-compact design that allows you to place it inside a laptop's briefcase comfortably. Others come as PCMCIA cards, which attach to any PCMCIA/PC Card slot. Most laptops come with this, but a desktop PC rarely has one. Just exercise plenty of care when choosing a card, since it must support the interface that all the computers you intend to use it on have.
If you want a card that fits in almost any computer, get one with a USB 2.0 or Ethernet (network attached) interface. USB 2.0 transfers at a maximum speed of 480 MB per second, enough speed to relay even the most impressive HD videos. You can't go wrong with Ethernet either, designed to transfer at speeds of up to 1 GB per second. Either one is fine, as virtually every computer you will ever encounter uses USB 2.0 and Ethernet ports. If you don't want to interrupt the Internet on a particular computer, though, you'd have to hook it up to a router that gives the computer and the external video capture card access to the network without a direct connection between them.