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:
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
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.
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 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.
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.
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.*
*Actually, the Mpeg compression organisation
(MPEG stands for Motion Picture Experts Group) plan another
format called Mpeg-7. Since Mpeg-3 no longer existed they thought
it might be best to follow a new numbering system of 1, 2, 4,
8 (which was the number system used by computers), but instead
they chose lucky 7! Mpeg-7 will not be a new compression format
used as a replacement for any of the others but rather a standard
that glues them all together.
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
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:
"I reverse engineered the ASF file format. This was done
legally; I created my own content in both AVI and ASF form
and compared the results at the byte level, without disassembling
the ASF file format drivers themselves. I don't see what intellectual
property Microsoft could claim in ASF, it being a universally
unimaginative and poorly-designed format.
Microsoft most likely had a bone with VirtualDub because
its ASF support had two important features that the people
in Redmond did not want available. The first is that, since
VirtualDub treated ASF essentially as a poor man's AVI, it
was capable of processing ASF files in Direct Stream Copy
mode, meaning it could rip the frames out to AVI at over 4,000
frames per second. The DirectShow filters force real-time
conversion, and the DirectShow AVI output filter mucks the
audio synchronization. The second is that, more generally,
it allowed compressed ASF files to be transcoded to other
I received a polite phone call from a fellow at Microsoft
who works in the Windows Media group. He informed me that
Microsoft has intellectual property rights on the ASF format
and told me that, although I had reverse engineered it, the
implementation was still illegal since it infringed on Microsoft
patents. I have asked for the specific patent numbers, since
I find patenting a file format a bit strange. At his request,
and much to my own sadness, I have removed support for ASF
in VirtualDub 1.3d, since I cannot risk a legal confrontation.
This unfortunately means that I can no longer redistribute
versions of VirtualDub older than V1.3d. (I did appreciate,
though, that I heard this through the programming staff and
not the legal department)".
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
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 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!
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