CUTTING EDGE

With the addition of the new Pinnacle Cinewave video capture card, an Apple G4 733MHz (seen here running Apple's own DVD Studio Pro software) is a digital media powerhouse, capable of working with uncompressed broadcast‑quality video and audio.

Video and audio technologies are converging in all sorts of ways: musicians can now consider creating demos on DVD, and developments in digital video may show the way for better ways of recording digital audio. Dave Shapton puts it all together.

Remember Zip drives? You've probably got one, possibly even attached to a sampler. About five years ago they were a great solution to all your storage problems. Seventy floppy‑disks' worth on a single Zip disk. Fantastic.

They're a bit slow, though, especially if you use the parallel–port version. I'd even prefer ironing to waiting for the 20 minutes that these things can take to copy 100Mb of data. That's over three hours per Gigabyte. (They go faster on some computers, depending on how your parallel port is set up.)

The only reason for talking about Zip drives (apart from wondering aloud why anyone would buy them, now that CD‑R blanks offer storage for a fraction of the price per Megabyte) is to provide a framework for comparison with a device I came across a couple of weeks ago at a product launch.

The beast in question was the new Apple G4 733 with a SuperDrive, the new Pioneer–sourced DVD‑R drive. It had eight 18Gb 15,000rpm (revolutions per minute) SCSI drives configured in a Raid level 0 array, which basically uses the drives in parallel, giving access to their combined data rates. It also had a Gigabyte of RAM. And that's the boring bit — because this particular Apple artifact also had the most powerful video capture card in the universe.

It's called the Cinewave and is made by Pinnacle, one of the more innovative manufacturers of professional digital video equipment. Cinewave is special because it not only works with uncompressed PAL and NTSC video, but with uncompressed High Definition video as well.

I know I'm always banging on about data rates and compression ratios in this column, but, like it or not, our experience of digital media (and hence, to some extent, the world out there) is completely bound up with how much data we can move around in a given time. This quantity is referred to as bandwidth, and it is easy to understand the most basic rule about it. There's never enough.

Because there's never enough, we have to squeeze our media data into a smaller volume, so that it can get from A to B using whatever bandwidth is available — and though compressed data can be good, it's never going to be as good as the original. That's not an issue with Cinewave, because it doesn't have to use compression.

This is great news for video makers, because it means that it's now possible for them to work with totally broadcast‑quality video (and audio, to some extent), with no fear whatsoever about quality issues.

Films Without Film?

Apple's i‑DVD program has a simple interface that aims, as this screen shot implies, to make child's play of creating your own DVDs.

Before I go on to explain what High Definition video (as mentioned above) actually is, and what it has to do with music and musicians, here's a bit of background about HDTV. A very little bit, in fact, because the history of TV broadcasting in the last 20 years is a litany of unsuccessful attempts to establish an HDTV standard, and I'm not going to waste any more of Cutting Edge's column space on it than I absolutely have to. The fact is that HDTV is something that the Americans have now, and we don't. (What we have instead is Widescreen TV, which is actually even lower quality than ordinary TV, because it works by taking a normal TV picture and stretching it. In other words, the same amount of information as before is spread over a bigger area.)

But that's not the end of HDTV for us. At least, not if we go to see the next edition of Star Wars. Amazingly, George Lucas is filming the next epic on HD video tape, and in selected cinemas it will be shown on video projectors. It will be the first major feature film whose images have never been anywhere near film stock. And, if he wanted to, George could edit his next episode on a desktop Mac running Final Cut Pro, in native HD resolution. To me, that's a pretty important marker in computing's historical timeline.

Remember those Zip drives that take up to 20 minutes to transfer 100Mb? Fair enough — that's a lot of data. It's equivalent to 70 floppy disks, and you can get a fair sized book on a single floppy, as long as it's in plain text. Now get this: High Definition Television gobbles up data at the rate of 125Mb per second. That's one and a quarter Zip disks, or around 100 floppy disks, every second of every minute of every hour.

Needless to say, at the Cinewave product launch the G4's drives were working so hard it looked as though they were formatting themselves! It's staggering to think that a data stream of 125Mb (or one gigabit) per second could supply over 700 simultaneous tracks of 16‑bit audio, or nearly eight thousand MP3 streams. Enough, in fact, to play an entire record collection simultaneously.

The G4/Cinewave combination is a stupendous technological achievement. HDTV on a desktop computer is something that would have seemed impossible even last year. It still seems impossible, but it isn't.

Seeing Is Believing: Dv Projectors

The demonstration I saw could have been even better if Pinnacle had been able to use a projector capable of displaying the resolution of the video it was being fed. Coincidentally, I came across an ideal device when I visited JVC Professional recently.

JVC use a technology called D‑ILA in their video projectors, and they claim that it produces significantly better results than competing techniques. I must say that the pictures I saw were absolutely stunning, and when the mechanism was explained to me I realized that there are a few lessons that digital audio could learn from these video devices. (More of that later.)

JVC's projectors can display HDTV in the truest sense. They have plans to produce a model with a resolution of approximately 4000 pixels by 3000. (A pixel is a 'video atom', the smallest unit that can convey different information from the one next to it. The more pixels per unit of area, the higher the resolution of the device.) To put those figures into context, our domestic television standard specifies 768 x 576 active pixels.

One of these projectors costs about the same as a Ford Mondeo. That sounds like a lot, but it's not when you consider that this is essentially all you need to set up a cinema. Well, you need a building and a screen as well, but the point is that for about the same price as a small house (in the South East of England) you could set up an independent film theatre. Of course, you'd have to get your films transferred to a digital format, but over the next couple of years or so films will be distributed in a digital state anyway, possibly even by direct satellite link.

Movie Democracy?

To me, there's something about these HDTV developments that's even more exciting than the technology buzz: it's that at last there will be a way for talented film‑makers to get their works seen. Over the last few years, as mainstream films have become little more than vehicles for special effects, the chances for talented independent film producers to get their films distributed have continued to diminish. So it would be nice to think that the same frantic technological progress that is turning the popular cinema experience into little more than a theme‑park ride could also democratise film making and distribution.

With the ability to edit video at film resolution on the desktop, and the knowledge that they could show their work in a local independent, fully digital cinema, film‑makers would be much better able to get funding to pay the actors, and to hire the HDTV cameras, which cost around £600 per day. That may seem like a lot, but it's almost trivial compared to the cost of using film, and getting it edited conventionally.

All of this would be great news for musicians, because if you're anything like me, you'd love to write a film score.

A Sound Vision

I mentioned earlier that JVC's D–ILA video projectors use techniques that can teach us a thing or two about digital audio. I know it sounds like a bizarre connection, but whether we're talking about video projection or digital audio, what we're actually doing is converting digital media to analogue, and doing it, we hope, in the best possible way.

Until recently, the problem with digital video projectors has been that if you improve their optical performance all that happens is that you can see more clearly the pixels that make up the picture. That would be a bit like having loudspeakers so good that you could hear the individual samples. (You'd need ears that went up to 48kHz as well!). JVC's D‑ILA projectors get round this by actually abolishing the fixed pixel‑based structure completely. By using a free‑form 'lake' of liquid crystal, and stimulating it directly from the surface of a CMOS (Complementary Metal Oxide Silicon) imaging chip, their technology completely eliminates pixellation, since adjacent pixels simply 'blend' with each other. The effect is not hard to describe: it's just like looking at a 35mm transparency. To me, this is an almost ideal way to do digital–to–analogue conversion. Best of all, it's resolution independent. It doesn't matter how many pixels make up the video you feed into it — they all get smoothed out anyway.

What I'm describing here is nothing other than a low‑pass filtering process. It smoothes out the sharp transitions between the edges of the on‑screen pixels, and is related to what happens when we remove as much as possible of the original sampling frequency during reproduction of digital audio. With audio, the filtering process is carried all the way to the final stage of analogue reproduction: the loudspeaker. Speaker cones have a certain mass and that means that they have momentum, or a reluctance to stop moving. It is this unintentional side‑effect that prevents them from accurately reproducing any raw samples — which are essentially high–frequency square waves — that may be left in the audio signal. This won't, however, remove any artifacts such as aliasing that may have occurred upstream in the signal path, because they are the result of interaction between the wanted signal and the sampling frequency, and the effect of them is to produce nasty noises back in the audible spectrum.

We can learn from the way physical devices 'smooth out' digital's sharp edges. You see, it is possible to represent digital media as pure curves, rather than infinitely small dots in space and time (sampling, in other words). Postscript and TrueType fonts are typefaces described by curves, and not by a pattern of dots. Audio waveforms are already curves before we begin the process of trying to represent them digitally. Maybe we should be looking at techniques to keep them that way.