Infobase: About AV and DV Inputs on Camcorders


Many camcorders aren't just camcorders - they're digital recorders thanks to analogue and digital inputs. So what's all this stuff about DV and AV inputs, and why are they useful?


One of the most sought-after features of modern digital camcorders among those who wish to do more than just shoot and playback is the AV-in feature. To the complete newbie who is simply looking for a good camcorder, the whole business of a camcorder having a range of analogue inputs is a bit of a mystery. In fact, over on the popular and user-friendly SimplyDV Bulletin Board forums we're often asked: "Why on earth do I need inputs on my camcorder?". It's understandable. However, don't discount it. Having analogue and digital input capabilities on your MiniDV or HDV camcorder might be more useful than you at first think. Here's why.

What do we mean by Analogue?


Put simply, analogue is anything that isn't digital. Your older VHS, Betamax, S-VHS, Video, Hi-8 VCRs and camcorders all record analogue video and audio signals. If you copy a VHS recording from one machine to another you'll immediately notice that its quality degrades. Copy the copy and it will be almost unviewable.

MiniDV camcorder with AV cables connected
To view your VHS tapes (for instance) on a TV screen you need to have connected up the supplied cables - usually the set of Red, White and Yellow RCA Phono cables that carry stereo sound and video signals respectively (see picture, right). In Europe, users will probably use a single-connection SCART (or EuroSCART) connector. All of these carry analogue signals which degrade as they're copied and passed around between devices. Digital, on the hand, is the basis for all data that is created, copied, shared and manipulated by a computer. Deep down, it's just a complex sequence of binary code; essential we're talking Ones and Zeroes. It's either a "1" or a "0". It can't be anything else. Copy a sequence of ones and zeroes and you get the same sequence - so if your video sequence is a sequence of ones and zeroes which is then copied, you end up with something that's identical to the original. When a digital camcorder saves a sequence to tape or disk, it's writing a highly complex string of data which is then passed around to other devices according to your wishes - such as when you copy your DV footage to a computer for editing or you copy it to DVD disk.

So, what does this have to do with digital video camcorders?


Well, just because you have "analogue" video recordings doesn't mean to say that they have to stay that way. You may have some cherished family recordings on 8mm video cassettes or perhaps even Betamax that you wish to preserve on DVD and share with family members. You need to copy your analogue tapes to a digital device. In doing so, you're converting analogue sequences into ones and zeroes, and potentially preserving them forever. A digital camcorder with AV (analogue) inputs will enable you to get these onto DV or Digital-8 tape - or, if you have a DVD camcorder, onto DVD disk. Have a look inside the box that your camcorder came in and you'll see a cable that probably has three coloured cables (as pictured above) which all terminates at a single small jack plug. This is the one that you use to playback your movie footage on your TV or copy to a video recorder. If your camcorder has AV-in capability (the manual will tell you) then you can use this cable-set to copy analogue recordings to digital tape or disk in the camcorder, too.


AV-in-comp_520

Here we show you how to make the connections. The AV Cables that link the Analogue VCR to the Digital Camcorder are those referred to above. From the camcorder to your FireWire-equipped Windows or Apple Mac computer you'll need to use a FireWire cable.

Can I send the signal direct to the computer without re-recording to tape in the camcorder?


If your camcorder supports what's called digital signal pass-through then the answer is yes, you can. With the AV cables providing the inputs and the FireWire cable providing the digital conversion to the computer, it will be possible to send the digitised signal direct to the application being used to capture the video sequences to the computer's hard disk drive after which editing can commence. However, you may wish to play safe and back it up to digital tape as well.

Why is it useful to have a digital output on my digital camcorder?


Simple. Let's assume you've edited a set of video sequences in your Windows or Apple Mac computer and you wish to keep a safety copy from which you make analogue copies (eg: VHS) or even DVDs later. It's cheaper and better to keep a DV or Digital-8 tape copy.


DV-out-Comp

Notice in the diagram above that the configuration required is the reverse of that used to convert AV to digital. Using this method, it's possible to record to DV (or Digital-8) tape in the camcorder at the same time as copying out via AV cables to a recorder whilst viewing on a TV set. Refer to the respective user manuals to find out exactly what connections are required in this respect.

I've heard of S-Video. What is it?


Another type of analogue video connection is called S-Video, which can be detect by a little round connector and plug with several pins. S-Video is a type of analogue video processing called Y/C Component which processes the video signal differently by keeping the Chrominance (colour) and Saturation (the Brightness) elements separate. S-Video is used by S-VHS and Hi-8 formats, in addition to the professional Betacam-SP format. Unless your source is one of these, there's nothing to be gained by using S-Video. The S-Video cable carries only video; you still need to connect the Red and White RCA phono audio plugs, therefore.

Finally, what is a SCART plug?


A 2-way switchable SCART connecotr
If you live in Europe, you'll be able to benefit from a simple, single-plug connection for all video, audio and - in some cases - S-Video signals. For more detailed information about this, see About SCART.


Words and pictures: Colin Barrett, SimplyDV. No unauthorised reproduction or distribution. Copyright 2002, 2005, 2008.

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