Not too long ago digital audio was the big thing. And Compact Disc soon replaced vinyl records as the perfect medium for recording music. The technology was a huge breakthrough for the music industry. They could sell music that was practically perfect. There is no such thing as hiss on a digital CD. A CD could theoretically last for a hundred years or more and be played back thousands of times without any degradation in quality! The same revolution is now happening with TV and video. In fact, most of the technology for digital video has existed for many years now, but it is only in the early 21st century that digital video has really taken off. So what exactly is digital and why is everyone turning to it?

All of our old audio and video storage methods are what we call analogue. Analogue describes a method of storage that is continuous whereas digital describes a method that uses exact blocks. The most obvious analogy is that between an analogue watch and a digital watch. Analogue watches are the ones we see with hands on them. The digital ones have electronic numbers. When an analogue watch moves from number 1 to number 2 it cannot jump directly from one to the other, it must move between them first. A digital watch, however, will literally jump magically from number 1 to number 2 and there is no transition needed.

A Compact Disc (CD) stores audio by converting a sound wave into a kind of graph where the low-level tones represent low numbers and high-level tones represent high numbers. These numbers are stored with a special numbering system known as binary. Binary is, in essence, digital in its purest form! At primary school we are taught to add, divide, multiply and so on using a system based on decimal called base 10. The binary system lets us do anything we could usually do in base 10 but it works on groups of only two numbers: 1 and 0! For example, the number ten in binary would typically be written:

00001010

Yes, it's actually quite amazing! Hours of audio recordings can be converted into a single list of millions of ones and zeros! This conversion process is called digitising.

A CD itself is little more than a plastic disc with a thin layer of aluminium sandwiched between it. A laser burns pits into the surface of the aluminium producing thousands of bumps and gaps. Each bump represents 1 and each gap represents 0. Since our audio recording has been converted into a long list of ones and zeros it is now possible to burn our digitised audio onto our CD. Then when we put this CD into a CD player, another laser will bounce off of the aluminium bumps and it is that sequence of ones and zeros that are converted back into sound again.

The difference between a CD and a normal magnetic tape is that the average magnetic tape will try to store the actual wave but a CD will only store numbers. This means that any audiotape you buy is only 'roughly' the same as the original and no two are exactly the same. But every digital CD will always be a perfect copy of the original! That is the beauty of digital.

The CD uses a digital storage system; it is not inherently digital. To illustrate what I mean, there are actually magnetic tapes that store information in a digital form. These magnetic storage tapes are called DAT's (Digital Audio Tape's). DAT's also produce perfect copies of the original too because they store it as numbers. So audio CDs are perfect because they are digital and not because they use a CD to record on.

Carrying the digital equation even further, just about any electrical device could be made to use the digital system. This is what computers are all about. Computers are built out of millions of transistors etched on chips of silicon by rays of high-powered light. These off and on switches are represented by ones and zeros and are how all information is stored and processed on a computer.

Digital television and digital TV are still transmitted using radio waves, but now they transmit it in digital code. Not to say that to use digital encoding makes it impossible for errors to exist because its not, but digital is an all or nothing affair. On the old analogue TV sets it was possible to get interference or very bad picture quality. This is not the case with digital. You either get a practically perfect picture or just none at all!

DVD's vs. VHS

When you first buy a movie on VHS the quality is great. But after you have played it a number of times you find that the picture tends to produce noise, starts to jump or loose audio synchronisation. And who of us hasn't had one of their favourite movies or cherished home video chewed up in a faulty VCR?!

Digital versions of VHS have been developed (called D-VHS). But converting the signal to digital on magnetic tape couldn't solve any of the problems associated with VHS because it was the magnetic tape that was the problem. Even a perfect digital copy could easily get chewed up or become unplayable because of tape degradation.

Wouldn't it be great if we could record a movie on a CD instead! The advantages of CD's over magnetic tapes are obvious. They are much cheaper and faster to produce (typically less than one-fifth the cost). They are smaller and lighter, making them easier to ship. They are more resistant to heat and water damage. They can't get chewed up in the CD player and they cannot degrade in quality every time they are played. The only problem they have is it is sometimes possible to scratch them and cause read errors. Nevertheless, since they are encased in a thick coating of plastic it is was possible to buff out these scratches and restore them to a perfect condition again. I remember repairing a CD myself that wouldn't even play. I used nothing but motor car T-cut (burnishing cream) and a soft cloth. Such a repair would have been impossible with magnetic tape.

Another downside to using CD's are that they aren't very easy to record to like VHS. But from the movie industry's point of view this makes it the perfect format with which to release new movies, because people wouldn't be able make copies for their friends. If they liked the movie enough their friend would need to buy another copy from the shops - 1+1=10!

The Birth of CD Movies

Would it surprise you to hear that such CD movies existed even before audio CD's and have been around as long as VHS video recorders?! It's true! In 1978 the first Compact Disc Video (CDV) was developed and released by Philips and MCA. It was named LaserVision or LaserDisc and was able to fit 60 minutes of video on each side. It used an analogue storage method rather like vinyl records but the quality was great, certainly superior to any VHS video. Perhaps, like me, you remember the advert on TV of the swimmer diving into a pool. They paused it and it looked really clear like a photograph. The quality was so good that some people continue to use LaserDisc to this day!

The only problem with LaserDisc was that it didn't really catch on. Firstly, it proved far too expensive for most people to buy. The selection of movies was also limited and each movie required flipping the disc over half way through to continue watching. Add to that that each Disc was as large as a dinner plate and you have a rather unpopular format.

VHS on the other hand was a relatively cheap, convenient alternative that seemed to produce pretty good picture quality without the hassle or price of LaserDisc. And of course you could record to videotape whereas you could only watch LaserDiscs.

Video CDs

After the success of audio CD's in the early 80's attention was again turned towards the possibility of putting videos on CD again. By early 1984 JVC, Philips, SONY and Matsushita had developed a format that could fit 74 minutes of near-VHS quality video on a single audio CD! It was called Video CD (VCD) and later (as more features were added) CD-i. It used a new form of video compression known as Mpeg (pronounced em-peg).

Video compression is actually nothing new. VHS videos have always needed signal compression so that they were able to fit on such small magnetic tapes. This is done by filtering out parts of the picture and sound that you wouldn't notice missing. The Mpeg video compression was a breakthrough because it was many times better than anything else that had previously existed!

Again Video CDs proved quite unpopular in the western half of the world. But strangely enough they were embraced with open arms in Southeast Asia. In fact in to this day you can still buy a Video CD player and get almost any movie on Video CD there. Westerners didn't see the point in Video CD's. Although they never degraded in quality, they were barely as good as VHS video in quality. You couldn't record to them, and since 74 minutes was the maximum they could hold you needed to swap the discs by hand half way through the movie.

The DVD Revolution

In the early 1990s several companies pulled their talents in order to create an audio CD that was able to hold a lot more than the ones we were previously used to. These companies included such electronics giants as: JVC, Hitachi, Matsushita, Mitsubishi, Pioneer, Sony, Philips, Thomson, Time Warner and Toshiba. There was a huge potential market for this kind of thing, not only in the potential uses for audio and video storage but also because audio CDs had long been used by the home PC user to store and read data.

A new production system was devised. It used lasers of smaller wavelengths to burn much tighter tracks on the CD and dual-layer technology, which enabled each CD to hold two layers of information as opposed to the conventional one. In short, it was a CD revolution. Whereas a standard CD could only hold roughly 650 megabytes of information, the average DVD could hold 9.4 gigabytes! For the layman this is 14 times the size of a standard CD. And using the Mpeg compression again this meant they could now theoretically fit about 17 hours of VHS quality video on it!

By 1996 the standard for this new format was finalised. They called it DVD to mean Digital Video Disc, but then changed it to mean Digital Versatile Disc because it could be used as a data CD as well.

Obviously a 17-hour VHS quality video would be lovely, but since the average movie is only about 120 minutes long it was decided to bump up the quality a notch. The average DVD would now hold a maximum of only eight hours but it would be near studio quality video (that is based on the CCIR-601 TV picture standard). Needless to say the picture was amazing! Much better than a standard TV and many times that of a VHS videotape!

To achieve this they used Mpeg compression again, but this time it was the second edition of the format known as Mpeg-2. This compression system was redesigned and optimised specifically to handle TV signals much better than the previous version.

The sVCD

And here is where I enter the scene...oh wait! There was actually another format developed. It was called the Super Video CD (sVCD). This has a weird history because it appeared in 1998 which was two years after DVDs had been finalised.

So why make another format if DVDs were so good? Basically because the Chinese government weren't as stupid as the rest of the world. While most of the world were still using VHS tapes China were proudly selling millions of Video CD's. The western companies probably assumed that they would be the first to replace their Video CDs with DVDs. But China could see that DVD's were far too tightly controlled. The DVD consortium itself was a closed body of foreign companies and DVD's were non-negotiable formats that required region locks and high royalties to fix prices. For a country that had been leading the way in Video CD's such a deal must have sounded quite insulting. So instead, the Chinese government developed the Super Video CD, which they probably hoped would force the west to lower DVD prices.

In actual fact sVCD's presented very little competition to DVD. The Super Video CD did produce slightly better quality than VHS video but they used the same old 74 minute audio CD's to store them. They upgrade the compression system to use Mpeg-2 like DVD's, but in essence they were just making Mini-DVD's. The worst thing about sVCD's were that movies still had to be split across at least two CD's. I think this was its major failing. If they could have managed to produce VHS quality video on a single CD, then I'm sure it could have made a much better stand against DVD's than it actually did!

Digital Video on the PC

And here is where I enter the scene. A friend of mine was given a copy of a pirated movie from America. The weird thing was it was recorded on two small CD's. I was amazed! How could they fit a whole movie on such small CDs when only a few minutes of video capture seemed to fill an entire gigabyte! This is how I got into using Mpeg compression for making movies. I joined the on line video discussion groups and learned how it was done.

DVD movies appeared shortly after and the discussion soon turned to how we could decode them and make video clips for our use on the Internet or if it was possible to create Video CDs out of them. The reason we wanted to rip DVD was more because it was a challenge. There was no real possibility of making pirate Internet movies from DVDs even if that had been the reason any of us had wanted to convert them. By the time a DVD was released the movies were already a least year old and had all their sales already in both the Cinema and video shops. Very few people on the Internet would have wanted to spend ten hours downloading an old movie anyway!

At first everyone was using Mpeg-1 (VCD) compression to make their movies. This meant that with a fast enough connection you could send a fiend your latest movie within about five or ten hours of downloading. For me would have taken days to send large files like that across the Internet because of my very slow Internet connection. So I concentrated on making better Video CD rather than Internet movies like everyone else.

MPEG-4

In October 1998 the MPEG organisation released specifications for a new compression format they had been working on called Mpeg-4. It was the most advanced compression system they had ever built and was designed specifically for high quality Internet streaming video. For those of you who have been living on Mars with your eyes closed and your fingers in your ears, Streaming Video was a way of putting a movie on an Internet Website so that visitors could play it almost instantaneously. In other words, they didn't need to wait hours for it to download to view it. Of course, to make streaming movies produced a very bad quality picture when it is compared to VCD's. This is obvious, you cannot show in real time what would normally take many hours to download. Instead streaming movies needed to be compressed to the point that they could be downloaded almost as fast as they played.

I know what you're thinking, 'what happened to Mpeg-3?' Well, that was designed for the new High Definition TV's (HDTV) that were being developed. Half way through the project they decided that there was no need to improve on Mpeg-2 for high quality broadcasts, so Mpeg-3 was put on the back burner and they turned their attention to making a format for Internet streaming instead.*

Microsoft, in a desperate attempt to corner the Internet video market, got their hands on an early release of the Mpeg-4 specifications and produced a half-mpeg-4 format that we now know as ASF (Advanced Streaming Format) or WMV (Windows Media Video). The picture quality was great and beat anything else that existed at least when it came to streaming video!

The Problem With ASF?

Trading movies on the Internet had become quite popular at about this time (at least for those who knew how to do it). We all developed methods to convert DVDs to Mpeg-1 VCD either to trade, impress our friends or just for home backup purposes. But since ASF was so much better than Mpeg-1 for low bitrate compression everyone wanted a way to convert a DVDs to ASF - but there were problems!

Microsoft put a 'lock' on ASF files so no one could edit, copy, convert or even make them with anything but Windows Media Encoder. It was possible for software developers to buy a licence to add ASF support to their software but they still had to add this no edit 'lock' to all ASF files as part of the agreement. And no one could find any software except Media Encoder that could produce ASF files.

This made life very hard for us. We could convert the DVD to both Mpeg and AVI without too much trouble but we couldn't convert directly to ASF. Why not convert to AVI first and then convert that to ASF then, you say? This proved practically impossible too! Firstly a DVD was usually at least 4 Gigabytes (GB) per movie. This meant that before they even started to convert the DVD to AVI they needed more than 4 GB of free Hard Disk space. Secondly converting a DVD to uncompressed AVI takes around 1.7GB per minute of video! So if you wanted to convert the movie The Matrix to uncompressed AVI it would take at least 222 Gigabytes of space! Most people back then had a maximum hard disk space of 10 GB and the average was 6 GB!

Okay then, perhaps we could have converted it to another compressed format first and then to ASF? For example, it was theoretically possible to convert a DVD to high quality MJPEG first and then convert that to ASF. This was not an easy task either. MJPEG could keep pretty good quality but we were still looking at at least 6 GB or more for a whole movie! What is more, compressing into another format first damages the picture quality. So the picture would look worse if we converted it to MJPEG first. Finally, how long do you think it would take to convert to MJPEG and then to ASF? We are not talking about a couple of hours of trouble here we are talking a couple of days in some instances! Make no mistake, producing any Internet sized movie was a big task.

That was the main reason everyone hated ASF. But there were still other practical reasons why ASF's were a bad format. People were complaining about audio synchronisation problems. And after about version 4 of Media Encoder it became difficult to choose custom sizes and settings. It may have been a bit more user friendly (not!) but it also became more restrictive too.

The ASF format as a whole was wrapped up in bulky packets of information that helped them to stream video across the Internet. Because we wanted to have the highest quality video that could fit on a single CD, if we encoded a movie at say 700 kilobits per second (kbps) for a 600+ MB movie, we would end up with a 700+ MB movie instead! The extra padding seemed to make the Mpeg-4 file up to a hundred megabytes larger than was necessary! Since it was practically impossible to stream such a large ASF file anyway, all this extra bulk was just a waste. If it were somehow possible to use just Mpeg-4 without all the bulky ASF padding then we could make better quality movies in much smaller sizes.

There were programmers willing to help create applications to support ASF, but none of them wanted to follow Microsoft's ASF restrictions. Microsoft wouldn't stand for anyone who tried to support any part of the ASF format! For example, Avery Lee had produced what we all consider the best free video editing application ever made for the PC. The application was called VirtualDub and has so many features that many prefer it over such expensive video editing applications as Adobe Premiere! Concerning ASF support Avery Lee commented:

What Was DIVX?

When DVD's first appeared a system of pay-per-view DVD rental was developed by Circuit City Los Angeles entertainment law firm Ziffren, Brittenham, Branca & Fischer. They called it DIgital Video eXpress or DIVX for short.

DIVX was at best a bad implementation of a good idea and at worst an evil scheme designed to exploit the buyer! It was basically a DVD rental system a bit like Sky Box Office. You bought a DIVX player which was a DVD player with a modem connected to your phone line. Then you were allowed to buy any DIVX movie you liked for about $4.50. You could take the movie home and watch it as many times as you liked for a period of 48 hours. Then, every time you wanted to watch that movie again you would be charged $3.25. Then your DIVX player would send a note to the central DIVX computer through the phone line and unlock it for 48 hours.

The idea sounded good because you didn't need to worry about taking the 'rented' movie back to the shop late. It was also possible to order a movie and have it delivered to you rather than having to move your lazy ass!

Nevertheless most people hated the idea with a vengeance! Each disc cost more than a normal rental. It wasn't a true DVD, just a cheap cut down disc. They didn't have any extras, no widescreen and no alternative language support - you got the movie and that was it! You couldn't take the movie to watch at a friend's house because the DIVX needed to be unlocked. If your friend had a DIVX player they'd need to pay to watch it. You could "buy" the movie, which meant it was always unlocked, but you couldn't sell or give the movie to anyone else because they couldn't play it.

The telephone connection also allowed the makers of DIVX to track what movies you were watching and build up statistical data on viewing habits and tastes. Most considered this an invasion of privacy. Who wants the world to know how many times a day you watched 'Attack of the surfing, killer-bikini vampire women'?! Of course, saying that, Sky Digital and many Cable companies do pretty much the same thing!

Although DIVX got full backing by Twentieth Century Fox, Disney (Buena Vista), Universal, MGM, DreamWorks SKG and Paramount, in June 16, 1999 the DIVX scheme was discontinued.

Who was Gej?

Jerome Rota was a 26 year old French hacker, but we all knew him by his Newsgroup and IRC name Gej. Aware of the problems we had with ASF files, Gej decided it was time to hack the ASF codec and make a new one that would allow us to use the Mpeg-4 compression without any more restrictions. And by the summer of 1999 Gej, with a little help from a German hacker called Max Morice, succeeded! The final codec was amazing! It didn't incorporate any of the bulky extras from ASF. This meant it actually produced slightly better quality video for the same sized ASF movie! In a sarcastic pop at the old Circuit City DIVX Gej decided to call this new hacked ASF DivX ;-).

DivX allowed the Mpeg-4 part of ASF to be encoded as an AVI file. This was important because it meant that almost every video editing application in existence on the PC would now support DivX. It also meant that we could substitute the ASF audio for just about any audio format we liked. Since the ASF audio kept going out of synchronisation with the picture most decided that Mp3 audio should be used instead*. This fixed audio synchronisation and it also allowed us to choose higher quality audio than the current ASF format offered.

*As you probably already know Mp3 has revolutionised audio for the PC. It can compress CD quality audio from 50MB per track to 5MB with no noticeable loss in quality.

Since we were now working with AVI files we could also choose any resolution we wanted for the picture dimensions. To our amazement even at full DVD resolutions (720 x 480) the video quality was still great. It was much better than the Mpeg-1 VCD formats in most scenes even though VCD's was considered VHS quality video! Although commercial Video CD's needed two CD's per movie we could get near-VHS quality video on a single CD!