Thinking of buying a digital camcorder - here are a few tips
(S J Nixon)

In 1995, many companies agreed a new standard compression (codec) for video recording called DV (Originally DVC) and all digital camcorders use this standard. They also agreed to use standard digital tape cassette known as Mini DV. As a result, if you record digital video on any MiniDV camcorder, lets say a Sony, then you can play it back in a JVC or Canon and vice versa. (As long as you use standard play and not long play speeds) The quality of the video is identical and only depends on the optics of the camera and the skill of the camera man. In reality, modern optics are far superior to video recording so that means quality depends entirely on you. You can pay anything from £310 up to £3000+ for a digital camcorder but, as the final video quality will be the same, is it worth paying a high price ?

As technology moves on, the latest generation of camcorders record directly onto flash memory or even to a mini-dvd. Rather than using the DV codec, these new models use the MPEG2 codec. This codec is not quite as high quality as the DV codec but compresses the files size down further, allowing more minutes to be recorded in a smaller space. MPEG2 is used in commercial DVD players and is a high quality codec, perfectly acceptable for surgical use. A recent panasonic camcorder uses a 512 megabyte secure digital flash card for storage instead of tape but only seems to store 10 minutes of the highest quality on a single card. It seems certain that other manufacturers will follow this route and with 4 gig compact flash cards now available then 80 minutes of high quality could be stored on a single card. The main advantage of recording to a flash card (or dvd) over tape is the rapid transfer of the video files onto your computer hard disk for further editing. With tapes, transfer is in real time ie. 10 minutes of video will take 10 minutes to transfer to computer and this transfer can be a time consuming task .

If you are a surgeon, using a digital camcorder for both work and home then my advice is to look carefully at whether the camcorder can link to other equipment as the most important factor in choosing the model.

DV out

All digital camcorders send their data into a computer using an identical firewire connector. This will be described as DVout and all camcorders have one. Sony call this an i-link and others refer to IEEE1394. They are all the same. Although firewire was the standard method of connecting your camcorder to a computer, USB2 is now as fast and camcorders are appearing, some with both firewire and USB2 and others with just USB2. It may be that the days of firewire are numbered. However, you must remember that your computer must have USB2 as well and most computers sold today are USB 1 which is 10 times slower. If you connect your USB2 camcorder to a USB1 computer it will only transfer at the slower speed.

DV in

Only a minority of camcorders have the reverse ability whereby you can send digital video back from the computer to the camcorder and record back onto tape. This is essential as you will want to take a video from the camera to the computer, edit it and then send the results back to the camera to store the final result on tape (perhaps the cheapest archiving method). "DV in" is not essential and many camcorders do not have it. (In fact all camcorders do contain the electronics for DVin but the manufacturer disables it for "commercial reasons". There are 3rd party widgets on the market to activate this function if you have already bought your camcorder as it doesn't have DV in but there may be guarantee problems). Increasingly manufacturers are including DVin as standard.

Analogue out (S-Video out)

Most camcorders have a video out or s-video out which will allow you to connect the camcorder to the video in, s-video in or scart socket on your tv. S-video out is better than video-out but there is not much in it. As you may want to connect your camcorder to a video projector so that you can show high quality video to your surgical colleagues then your camcorder must have s-video (analogue) out. S-Video (Analogue) out is therefore essential. Some hospital equipment will refer to s-video as y/c. It is the same. The socket looks just like the sockets on the back of a modern pc for the mouse and keyboard to attach to.

Analogue in (S-Video in)

Very few camcorders have this facility although it is becoming more common. However it is extremely important for professional medical/surgical users. All modern camera stack systems used for laparoscopy, video endoscopy, arthroscopy etc and even most scanners eg ultrasound, doppler etc have an s-video (y/c) out. Your monitor may well have s-video out at the back as well. If your camcorder has s-video in then you can simply connect your camcorder to this equipment with a cheap s-video cable and record the video images directly onto your camcorder at digital quality. You can therefore record your operations onto your camcorder and you are using your camcorder as a digital video recorder taking video from another source. As you can run a camcorder on batteries for up to 8 hours then you shouldn't upset medical physics by plugging it into the mains. Analogue in (S-video in) is essential. You might also want to transfer your old analogue VHS, SVHS, hi8 etc tapes to digital and you can do this using your camcorder to record on to from another video recorder which has s-video out on it..

In a nutshell, if you are buying a MiniDV camcorder it should have DVout, DVin, Analogue (svideo) out and Analogue (svideo) in.

Another purpose that you may use your camcorder for is a real time analogue to digital converter which is all you need to make live video broadcasts on the internet. My JVC is able to take in svideo from another source and simultaneously feed out a digital signal via the firewire to a computer on which Microsoft's free encoder will convert it to a streamed file which is fed to a server and broadcast on the Internet, all in realtime. With a simple switch box taking in various svideo signals, lets say from another camcorder, from a laparoscopic stack and from an SVHS video, you can direct your program by simply switching input from source to source into your camcorder, broadcasting in real time on the Internet, all for the cost of a simple switching box. You are able to buy an analogue to digital converter, specially made for the job, for a few thousand pounds but it seems a pity to spend this money when your camcorder does it anyway. Another use of analogue to digital conversion is that you can use your camcorder between a laparoscopic or endoscopic stack and a computer so that, as you operate, the video goes via the s-video cable to the camcorder and then via the firewire to your computer so that the video is recorded directly to hard disk. At the end of the operation you can then rapidly edit the video taking out the poor bits and dramatically reducing the file size. If you record a procedure onto tape then it will take you the same length of time to cross it over to the PC ie a 30 minute operation will take another 30 minutes to transfer but when connected directly the transfer is occurring as you are operating and thus much reducing your editting time.

You can also use this to directly transfer old vhs tapes to your computer. I connect the svideo out from a vhs recorder into my camcorder. The camcorder has no tape in it. Then a firewire goes from the camcorder to the computer and I set my editing software (Pinnacle Studio) to record. Switch on the vhs tape and the video is recorded directly onto the computer.

Dazzle has a standalone device that will do this same job ie analogue to digital conversion. I have also just found an interesting gadget which appears to be a stand alone analogue to digital MPEG2 converter designed to fit as a card onto a notebook. Essentially you could plug your svideo out from the laparoscopy/endoscopy stack to this device and record MPEG2 video in real time directly to your notebook hard disk. Ultimately this might be the ideal and low cost solution for in theatre recording directly onto a notebook.

Back to camcorders, you can pay many thousands of pounds and not get these features but you can pay as little as £300 and get them all eg the CanonMV500i (the"i" is very important). Try Simply, Dabs, Jessops , RGB direct

Examples of low cost camcorders with all features include the JVC GRD70EK (£310), Canon MV600i (£430) and Sony DCRTV19 (£450). (Typical prices from www.rgbdirect.co.uk <http://www.rgbdirect.co.uk>) However, make absolutely certain before you buy. You may of course want to pay more than £300 for other reasons. Some people drive a Porsche!

Some Digital Camcorder with all four connection features