DV input jacks are found on video cameras, video transfer/recording and viewing devices using digital video (DV) compression technology. DV jacks employ what is technically known as IEEE-1394 protocol, with common brand names for computer use including Apple's FireWire and Sony's iLink. Devices with DV jacks are coupled with other devices similarly equipped with IEEE-1394 cable, allowing high-speed, real-time data transfer for recording or viewing.
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Purpose of DV Jacks
DV jacks are used to record, upload, download or display video information. Acting as both a DV input or output jack depending on the flow of video data information, typical use of DV jacks include connection of digital camcorders to DV jack-equipped televisions or computers. Some devices such as DVD recorders and other video recording machinery also employ DV inputs to transfer and record information to various recording media platforms such as Mini DV tape, SD cards or hard drives.
Daisy-Chaining DV Devices
The IEEE-1394 protocol used for DV jacks allows daisy-chaining multiple devices together for simultaneous video procedures. For example, an IEEE-1394 cable may be plugged into the DV input of a camcorder to transfer video to a DVD recorder. Another cable plugged into the DVD recorder's DV output may be plugged in a television set or computer DV input for viewing or video file transfer. The tasks are only limited by the number of DV jacks installed on specific equipment and up to sixty-three IEEE-1394 can be connected at once. IEEE-1394 components are "plug and play," meaning that they require no external installation drivers.
Types of DV Cables
DV cables for video use are typically of the four-wire variety, but some IEEE-1394 devices, such as printers and external hard drives with no external power source, require six-wire cables. Devices of all types may be combined in a daisy chain, but adapters or special six-to-four wire cables may be necessary when combining powered and non-powered components.
DV Jack Data Transfer Speed
IEEE-1394 on the computer end is available in 400 or 800 Mbps (megabytes per second) transfer speeds depending on the circuitry installed. Similarly, devices are either configured for 400 or 800 Mbps transfer. The "transparent" design of IEEE-1394 -- whether used for DV jacks or other applications -- allows devices of both speeds to be connected to computers or devices of either speed. Hence, the actual transfer speed is dictated only by the limitations of the connected devices and is not inhibited by slower or faster devices in the chain.