What Do All These Different Video Connectors Mean?

[ This article was first published in the March, 2005, issue of
Larry’s Monthly Final Cut Studio Newsletter. Click here to subscribe. ]

While we are on the subject of hardware, another reader, I must confess I lost his name, asked me if there was a difference between all the different video outputs on his tape deck.

Which set me to thinking. I’ve worked with decks for so long that I just take their various outputs for granted. So, if you’re new to this whole video thing, here’s a quick primer.

VIDEO CONNECTORS

Let’s start with the connectors. There are four principal types of video connectors:

Jerrold, or F-connector

RCA

S-video

HDMI

BNC

The F-connector screws, or slides, onto a post on the back of your deck or TV set. This connector is used for connecting RF (radio frequency) signals. While very useful in connecting a VCR to a TV set, it has very, very limited use in professional (or even semi-professional) video. It’s principally used for RF signals.

The RCA connector is the one that’s used on most consumer gear. Normally used for audio signals, it can also be used for video when inexpensive connectors are required.

The S-video connector, unlike the other three, has four wires to cary video signals. (The others all use two.)

HDMI is designed for high-definition media. An HDMI signal includes both audio and video, but not timecode. (HDMI stands for High-Definition Multimedia Interface.)

The BNC connector is a twist-lock silver plug used in most professional video installations. The twist-lock means it won’t come off by accident. Due to the way it is constructed, and the quality of the wire attached to it, BNC connectors provide higher quality and more secure connections than RCA connectors. (BNC stands for Bayonet Neill–Concelman.)

VIDEO OUTPUTS

Now, back to our discussion of outputs. Depending upon format, and how much you spend, a tape deck can have up to five input/output options. Here’s a quick description of each, from lowest quality to highest (and cheapest to most expensive):

• Composite. This uses a single connector, either RCA or BNC, that is the lowest common denominator for all video sources. It is the traditional connection on VHS decks. It provides an acceptable level of quality, but nothing you’d write home about.
• S-Video. This uses a higher quality signal, with greater resolution and less color “fuzziness.” This is an excellent option for connecting decks for dubbing.
• Component. This uses a three wire connector, where each wire carries part of the color components of a signal; as well, the green wire also carries the black-and-white signal information. This is the best choice to provide the highest quality for analog signals. It is the preferred connection for Betacam SP and other analog tape formats. As well, it is commonly used for DVD output to a monitor.
• Firewire. This is a 4-wire digital signal (the other two connectors on a six-wire FireWire connector carry power to the external device). As FireWire is digital, the quality of the image is determined by the source format, rather than the transmission. Generally, FireWire provides the highest quality for DV signals.
• HDMI (High-Definition Multimedia Interface) is the most popular choice currently for connecting monitors, TV sets and projectors. HDMI signals include audio and video, but no timecode.
• SDI (Serial Digital Interface). This uses a single wire BNC connector to carry standard-definition digital signals. This is the standard digital interface in a broadcast/high-end post production environment because of its ability to travel longer distances than FireWire. It is the preferred connection for DigiBetacam decks. This format has been, in most cases, replaced by HDSDI.
• HDSDI (High-definition Serial Digital Interface). This uses a single wire BNC connector to carry high-definition digital signals. The connectors and cables look identical to SDI connectors, the difference is the speed and protocol of the signals they are carrying. HDSDI is preferred over HDMI due to support for audio, video and timecode on a single cable, as well as longer runs than HDMI supports.

While there are a few technical benefits to capturing DV-recorded output using an SDI connection on a very high-end deck — specifically for converting color sampling, or integrating Betacam and DV footage — in general, a FireWire connection is the best method for transferring DV footage into your computer.

For higher-quality or higher-resolution formats, HDSDI is the best option for signal quality, resolution and distance.

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