TV Tuner Cards
A TV tuner card is a kind of television tuner that allows television signals to be received by a computer. Most TV tuners also function as video capture cards, allowing them to record television programs onto a hard disk much like the digital video recorder (DVR) does.
The interfaces for TV tuner cards are most commonly either PCI bus expansion card or the newer PCI Express (PCIe) bus for many modern cards, but PCMCIA, ExpressCard, or USB devices also exist. In addition, some video cards double as TV tuners, notably the ATI All-In-Wonder series. The card contains a tuner and an analog-to-digital converter (collectively known as the analog front end) along with demodulation and interface logic. Some lower-end cards lack an onboard processor and, like a Winmodem, rely on the system's CPU for demodulation.
Analog television cards output a raw video stream, suitable for real-time viewing but ideally requiring some sort of video compression if it is to be recorded. More advanced TV tuners encode the signal to Motion JPEG or MPEG, relieving the main CPU of this load. Some cards also have analog input (composite video or S-Video) and many also provide a tuner (radio).
An image of TV tuner card
Video capture cards are a class of video capture devices designed to plug directly into expansion slots in personal computers and servers. Models from many manufacturers are available; all comply with one of the popular host bus standards including PCI, newer PCI Express (PCIe) or AGP bus interfaces.
These cards typically include one or more software drivers to expose the cards' features, via various operating systems, to software applications that further process the video for specific purposes. As a class, the cards are used to capture baseband analog composite video, S-Video, and, in models equipped with tuners, RF modulated video. Some specialized cards support digital video via digital video delivery standards including Serial Digital Interface (SDI) and, more recently, the emerging HDMI standard. These models often support both standard definition (SD) and high definition (HD) variants.