BOOT CAMP 179 (14/06//01)

CAMCORDERS AND COMPUTERS part 2

Camcorders and computers seem like unlikely bedfellows but it's a marriage made in heaven. As we showed last week the new generation of digital camcorders are capable of recording professional quality video and audio but the key feature, as far as we are concerned, is that they talk the same language as computers. The picture quality of older analogue models (VHS-C/S-VHS-C and 8mm/Hi8 tape formats) was not that good to begin and it suffered horribly in the two-way conversion process, necessary to get recordings into and back out of a computer.

However, the question that we started to address last week is, what is the advantage of editing using a computer to edit video recordings? Anyone who has owned a camcorder will know that it is a relatively easy matter to edit video recordings using an ordinary VHS VCR simply by copying across the scenes you want, in the required order. The results can be quite good, especially if you start out with high quality source material and use a decent VCR. After all, the end result, an edited recording on tape, will be the same whether you use a VCR or a PC.

The fundamental differences are summed up in the terms 'linear' and 'non-linear', which are applied to tape-based and PC-based video editing respectively. Linear editing simply means that the scenes that you want in the finished recording are strung out along a length of tape and it takes a finite time to access each scene by winding the tape back and forth. That means that you can only do simple 'cuts' and 'fades' at the point where one scene ends and the next one begins, rather than the more elaborate 'transitions' used in professionally made TV programmes and movies whereby the end of one scene is gradually 'wiped'  'mixed' or 'cross-faded' into the next. (Actually you can, but you need at least two 'source' VCRs and some very fancy electronic gadgetry).

PC editing is non-linear; raw footage is downloaded onto the PCs hard disc drive. The drive can then access any part of the recording in a fraction of a second, so quickly in fact that there is no noticeable interruption in the picture as it jumps from one scene to the next, even if they originated at opposite ends of the tape on the original recording. Moreover, scenes can be joined together using a huge range of transitions and eye-catching special effects.

What makes this process even more interesting is that it is all digital, from start to finish, up to the point when the finished recording is copied on to VHS tape, though many users prefer to stay in the digital domain and record back onto digital tape, to maintain quality. In theory there will be no loss of quality and the parts of the recording that end up on the final edited copy will be perfect  'clones' of the original. In practice, depending on the PC hardware and software there may be some minor processing errors or 'digital artefacts' in the finished recording, though these tend to be much less noticeable than the significant increases in picture 'noise' and loss of detail that occurs with linear editing on domestic analogue video equipment.  

Editing on a PC is also a great deal quicker and easier than tape-based systems and most operations use familiar mouse click and drag and drop techniques. The majority of editing packages use a simple 'Timeline' presentation for the main editing screen, where scenes or 'clips' from the original recording are trimmed to size and joined together as a sequence of thumbnail images. The same Timeline also shows scene transitions and the audio soundtrack, which can also be edited and mixed. Most editing packages also have graphics and title facilities and a huge range of special effects that allow you do lots of fancy tricks with the picture (swirls, bursts, elaborate wipes etc.). Incidentally having so many 'toys' to play with can be curse as the temptation for newcomers is to go wild and a lot of first attempts often end up looking like a dogs dinner…

If you have a digital camcorder and a PC and you like the sound of non-linear editing then there are a few things that you should be aware of. The first is that you can't use any old PC, even if it's a reasonably recent model. The three man criteria are processing speed, memory and hard disc storage space. The first two are unlikely to be a problem if your PC is less than two years old, most editing software calls for a Pentium or Pentium class processor of 500MHz or faster and at least 128Mb of RAM. The hard disc requirements tend to be a little more demanding because of the huge amount of space that digital video data takes up, and the need to be able to get at it quickly. As a simple rule of thumb footage from a DV camcorder takes up around 3.5Mb per second, which roughly translates as 4 minutes per gigabyte. Put another way, 60 minutes of raw camcorder footage will require at least 15 gigabytes of free disc space, add to that what the program itself needs and the workspace it requires to process and render special effects, then there's Windows and any other applications you might have, and you won't be left with much change from 20 to 30 gigabytes. If the disc drive is heavily used for lots of other things then it can become slow and fragmented, which may result in reduced picture quality.

The simple solution is to add a second hard disc drive and use that exclusively for video editing, suitable drives are now available for less than £100. Serious and professional video movie makers tend to favour the system approach and buy or construct their PCs from the ground up with video editing in mind, using the best components. Basic editing packages, complete with software and all the necessary hardware to connect to a digital camcorder, can be put together for around £1000, though beware, if you get really hooked, the sky's the limit! If you want to get a taste of PC editing you could do worse than try one of the starter packages that work with analogue or digital camcorders and connect to the PC via the USB socket or parallel port. There are plenty of them choose from, selling for less than £100, including cleverly branded products designed to encourage kids to make their own movies and animation. If you've ever dreamed of getting into movies, this could be the start of something big…

Next week –  Top Ten Traumas

JARGON FILTER

DIGITAL ARTEFACTS

Processing errors in digital video recordings, typically the picture freezes momentarily or breaks up into large 'pixellated' blocks

RENDERING

Time needed to process a scene transition or special effect. Faster PCs can render effect in real time – i.e. instantly – slower machines may take several minutes to produce a simple wipe or fade

TRANSITION

The changeover point in an edited video recording or movie from one scene to the next, i.e. 'cut', 'wipe', 'mix' or 'fade'

TOP TIP

Excel users – and we happen to know there's quite a few of you out there -- here's a neat little trick that old hands are probably familiar with, but newcomers might find useful. If you have a column of numbers that you want to add up quickly, simply highlight them and the SUM of the numbers appears in the Status bar at the bottom of the screen. There's more, if you now right-click on the Status bar result you'll see a set of extra options, including Average, Count, Count Numbers, Min and Max.