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computers and creating 3D computer animation in sync with music.
Computer-Music.com is also the home page of Donald S. Griffin, an
experienced professional composer, sound effects designer and audio consultant
with an emphasis on computer games, video games and internet music and
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Article #1:
Composing Music Using Computers
An Introduction
By Donald S. Griffin 10-10-96
- Welcome To A Brave New (Musical) World
- Understanding MIDI
- Understanding Digital Audio
- Making Music using MIDI and Digital Audio
Other articles in this series:
Welcome To A Brave New (Musical) World
Composing music has always been a giant step forward even for an accomplished musician. Most people seem to think that composing music is the same as playing it except that you are writing it instead of reading it but that is exactly what makes the two activities so different, almost opposite. A musician spends many thousands of hours over many years training his/her body and mind to react to the sheet music with complex sets of reflexes that allow them to break up the very complicated task of playing the music into larger sections that they already know how to do without thinking. This is similar to the way you read whole words, not the individual letters in the words. This allows you to use your mind to comprehend what you are reading instead of spending all your effort putting words together from letters. Music is a lot like reading three or four or even five separate lines of text all at the same time with the additional requirement that you not slow down and that you physically respond to every word. This is no simple task and takes seemingly forever to get good at. In fact, nearly every musician in the world is constantly practicing and improving no matter how good they are. My father was fond of quoting a famous clarinetist who is supposedly said "I don't play the clarinet anymore. I play the music." Overcoming the need to constantly think about what you are doing gives you the opportunity to be think and be creative about how you do it. Just this goal is enough to keep most musicians busy for the rest of their lives.
Now consider how different writing a story is from reading a story. A story writer has to understand how the way words are put together effects the reader. A composer has to understand how musical sounds effect the listener. Just as with the musician who must master the basics of music to free up his/her mind for more creative interpretation of the written music, a composer music find a way to organize his/her musical thoughts so that the details of putting notes on paper don't become overwhelming.
When I was the 7th or 8th grade I had a new music teacher whose family often formed a Dixieland Jazz band. Dixieland Jazz is one of the purest forms of Jazz in that very little is agreed upon in advance and there is usually no sheet music at all. The key to doing this is called improvisation, making up notes to fit as you play. He started by writing a C scale on a sheet of music paper to allow me a small connection to my familiar world of the written note. He then said "I will play a pattern of chords on the piano while you play any of the notes on the page in any order and rhythm you want." It was just that simple and complex at the same time. It was also a pivotal point in my life. It turned me from one who reads into one who writes. I got better at improvisation and it didn't take long to realize if it was good enough to play then it was good enough to write down and play again. I also felt the need to improvise more than one note at a time, chords. Maybe its a lucky thing I didn't already play piano or the urge to write for groups of musicians may never have come to me. The need to figure out what notes went together and why led me to take guitar classes in school and reverse engineer the songs. I was told where to hold my hands to play the chords but I had to figure out for myself why. As my compositions became more complex and I was writing for combos then 9 saxes then a whole Big Band (about 20 musicians) the task of loading the whole tune up to that point into my memory and maintaining that sound picture in my mind before I could continue revising it became horrendous. It was great training but I hated it. I would spend 2 to 4 months writing a conductor's score then hand copying all the individual instrument parts from that score being careful to make it so readable that a musician wouldn't make a mistake and ruin my music. Then I had to photo copy each part, knowing full well not to trust musicians. Eventually the day would come when I would get some unsuspecting Big Band to read through once, then record my music. Only at that moment would I know for sure what it sounded like. Often they would call me to their chairs to point out a note that they thought must be a mistake. Usually it was not but verifying that fact often wasted valuable time. When it was a mistake it only showed up in playing because it was not until then that I could hear it myself. What I needed was a robotic jazz band that would play the right notes on the right instruments with impeccable skill and always be at my beckon call. I'm not kidding when I say the I really had those exact thoughts years before anyone had a home computer.
I had written some 20 odd big band scores and was doing pretty well when my father brought home a Texas Instruments TI-99 4/A home computer with 16k of ram and a cassette deck to save programs on. It had a simple synthesizer that could play up to four notes (sine waves) at once but only if you typed in line after line of code saying the frequency (which you looked up on a chart) for each simultaneous note and the duration in milliseconds. Each command was a slice of time so if one note was longer than the next you had to put the time they played together as one command then extra length of the longer note as an additional line of code. My father was blown away when I sat down in one continuous session typed in a long tune from top to bottom without any editing and it played right the first time. I still have it on tape and it took me years to realize how amazing and how pitiful it was at the same time.
I've spent a lot of words up to this point because I was afraid that without that background you would not appreciate just how colossal an improvement MIDI sequencing is. Today MIDI Sequencing software gives me everything I wanted in 'the old days' and then some. I can hear my music the second I create it. I have a nearly infinite variety of musical instruments at my disposal and I can try out new ideas that I can't hear in my head to see if they have merit with very little effort. I can easily print out conductors scores or individual musicians parts which I rarely do since my musicians are usually electronic. After hearing a finished tune I can easily make major changes and hear it again with no muss and no fuss. If I had access to these amazing tools when I was just starting out there is no telling what I could have learned or how fast I would have gotten to this point. It was very useful to learn how to do it in my head but. Let me put it this way: Long walks are healthy but how many of you walk to work every day? With today's MIDI and digital audio sequencing software anyone with a computer, a sound card, speakers, and some time can learn to be a musician and how to compose music without the need for the good graces of scores of musicians just to hear what you have written. In the following paragraphs I will explain what MIDI is and how it works and give a brief orientation on digital audio then explain how you would use this knowledge to make music using a MIDI sequencer.
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Understanding MIDI
MIDI (Musical Instruments Digital Interface) is a system for cross compatibility between unlike makes and models of synthesizers. MIDI data is not a recording of the music itself, rather it consists of simple instructions for playing music. When you play a MIDI file you are sending a stream of MIDI messages that 'play' your synthesizer chip much like the paper roll in a player piano. MIDI files are much, much smaller than digital sound recordings and MIDI data can be altered in meaningful ways 'on the fly' so MIDI is a powerful tool for providing interactive music in computer games because there is usually not space for digitally recorded music on the game disks or in memory and because it allows the music to change as you play the game.
General MIDI (GM) is set of guidelines for synthesizer design which allow one GM music file to play reasonably well on different models of synthesizers. GM was designed to allow friends to share MIDI music files without requiring all manufacturers to make their synthesizers sound exactly the same. Roland later designed an enhancement of GM called GS which is essentially 'GM with some extra stuff'. Any synthesizer which is GS compatible is, by definition, also GM compatible. Later Yamaha came out with their own idea how to extend the cross platform compatibility of MIDI files in a new standard called XG. Again any synthesizer that is XG can play GM files. Many sound cards in today's computers still have OPL-2 or OPL-3 FM synthesizer chips made by Yamaha or similar chips made by other companies. They are essentially FM synthesis in it's weakest form and not only sound cheap but are usually not capable of enough simultaneous tones to accurately play back many GM files even though they may claim to be using a GM sound set under windows. If you are picking a sound card and want to get good sounding MIDI music out of it you are better off if you choose one that has a 'wave table' synthesizer on board although the retro compatibility that an FM chip provides can't hurt if it is in addition to the wave synth and not instead of it. Many sound cards have pins to allow you to connect a wave table 'daughter card' (a card which plugs onto another card) that will add the synthesis ability of the daughter card without having to buy a whole new sound card while keeping whatever FM compatibility your current card provides as well as maintaining its digital audio capabilities. These daughter cards are often less than half the price of the stand-alone versions of the same synthesizers from the same manufacturers and are a great deal if you already have a sound card with daughter card connections. The AWE-32 from Creative Labs has daughter card connections even though it already has FM and a wave synthesizer. This is a good thing since the wave synth uses only 1 megabyte of ROM which is considered, by most industry professionals, to be inadequate space for storing a decent sounding General MIDI sound set . The AWE-32 has done an admirable job considering those constraints and has space for up to 28 megabytes of sample RAM but you have to buy and install the RAM chips and you have to load the new sound set onto the card each time you power-up the computer which is easy compared to acquiring a good sound set in the right file format. The AWE-32 is all-in-all a worthy device and I would recommend it if it fits your needs but you might want to consider adding a daughter card from Roland (now sold under the name Edirol), Yamaha, or Kurzweil in order to fully appreciate what MIDI can sound like.
MIDI is often knocked by people who don't know any better. I belong to several industry groups who routinely share jokes and laughable quotes about how MIDI supposedly sounds bad. In fact if you watch TV today and you hear music in a commercial or TV show or movie it was most likely produced using MIDI. In this case it is recorded and you are hearing the recording being played back as part of the TV sound track. MIDI in a computer game is actually being performed in real time on your computer's sound device as the software sends a stream of MIDI messages to your sound card. What makes the difference between the quality of MIDI music you hear on TV and the usually lesser quality heard on your computer comes from three things: 1) The quality of the synthesizer hardware in your computer. 2) The quality of the instrument samples on the sound ROM in your synthesizer. 3) The quality of the MIDI data (generated by the composer) being fed by the software to your computer's MIDI device which is either on your sound card or connected to your computer's MIDI interface via a MIDI cable. In short: MIDI is only as good as the software and hardware which are using it. MIDI is just a communications protocol.
The MPU-401 MIDI interface, designed by Roland, is the most commonly supported MIDI input/output format and as such is supported in nearly every new sound card as a means of getting MIDI data from your software to the synthesizer on your sound card.
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Understanding Digital Audio
To understand digital audio it helps to understand the difference between analog and digital as it refers to sound recording. Analog sound recordings are continuous representations of the changes in sound pressure (air pressure) to the diaphragm of the microphone that recorded them. How the sound gets from the microphone to an analog recording medium like a vinyl record or a cassette tape is not important here just that it is a continuous, unbroken stream. If an analog recording was to be represented by a graph you would have to put the pencil down and draw a smooth curving line without lifting your pencil. The actual recording has theoretically infinite detail since you can pick any two points on the line, no matter how close together and find a new point between them. This is not to say that analog recordings are of infinite quality. In practice every step along the recording chain is flawed so not every detail of the sound is accurately recorded.
Digital recording is not perfect either, just different. The key word in understanding digital versus analog is the word digit. Whereas an analog recording is stored on a medium that allows a continuous curve of changing sound pressure values a digital recording does not. Digital recordings are a series of snap shots of the sound pressure at a precise instant stored as a number, as digits in a computer. In a digital recording you can find two points right next to each other for which there is no value between them. A digital recording would be best graphed as a series of stair steps since it is not known what the values are between the points where the sound pressure was actually measured. If you measure the sound pressure often enough and accurately enough you can see a graph where the stair steps are so small they are almost invisible and the graph SEEMS to be of an analog recording. If you add to that the fact that the equipment that plays back digital recordings does some guess work to recreate the missing points in between each actually measured point you can get a pretty detailed picture of the sound with digital recording even though you didn't actually constantly measure the changes in sound pressure the way you would in analog recording.
Digital recording has several major advantages over analog recording. Digital recordings are numbers which means they can be manipulated buy computers. They can be stored as a list of numbers which will stay the same quality from copy to copy so long as nobody changes the numbers. Analog recordings lose some detail and gain some inaccuracies with each subsequent copy. With our present technology we are able to make and play back more accurate recordings using digital technology than analog.
In digital recording there are some decisions to be made that don't apply to analog. You have to choose how often you will record each sound pressure value and how big is the possible range of values you will allow for each measurement. If you are recording using an 8 bit number to represent each sound pressure measurement you can only have 256 possible values so you have to divide all possible sound pressure levels into 256 ranges. If a level falls between two of these possible values it has to be rounded off. This rounding off adds to the stair step effect and the sound can not be reproduced as accurately as if there were more possible values. This results in the recording sounding scratchy when played back and a loss of high pitches. The other common vertical resolution or bit depth or amplitude range is 16 bit recording. 16 bits offers a vast increase of sound pressure ranges from 256 to 65,536 which is what music CDs use. How often you record each measurement is called the sample rate or sample frequency. This is not the same as the sound frequency but they are related. The Nyquist theorem (pardon any mis-spelling) essentially says that the highest sound frequency that can be reconstructed from digital sound data is half the sampling frequency. Essentially that highest frequency is being graphed with only two points per cycle. If you want to reproduce sounds up to 22.05 kilohertz (22,050 cycles per second) you have to use a sample frequency of 44.1 kilohertz (44,100 samples per second.) This also points out the fact that the higher the sound frequency that is being recorded, the more vulnerable digital technology is to misrepresenting it during playback. In the above example (which is used in audio CDs) a sound at 22.050 Kilohertz would be reproduced by the computer producing only two points per cycle and the playback hardware would have to guess what the exact curve looked like when it was recorded. Because of the way that guessing works a flat horizontal line is often interpreted as a series of different frequencies at different amplitudes which would add together to produce something like that flat line if recorded at an inadequate resolution. The result is that any sound recorded without enough detail (without a high enough sample rate or enough bits for accurate values) tends to be reproduced as a terrible scratchy noise including high pitched sounds that were not in the original sound at all.
You might conclude from the above paragraph that you should always record digital audio at the very highest resolution possible but each sample has to be stored and takes valuable time from the computer to play back. For a typical CD recording at 16 bits and 44.1 Kilohertz the cost in disk space is just over 10 megabytes per minute if the recording is stereo. This is how a large capacity CD gives you 65 minutes of music. This is fine for a CD player since its computer is designed just for this task and has nothing better to do with its time but in computer applications and especially over the Internet the size of sound files and the time it takes to send them and the effort it takes for the computer feed them to the sound card for playback really matters. I recently downloaded a 10.5 megabyte file from the Internet using a dedicated Internet server (which is almost twice as fast as a service like Prodigy or America Online) and using a 28.8 modem connection it took just under 68 minutes. This means to hear a one minute sample of music over the Internet would take me over an hour! These numbers also point out that an hour worth of CD level sound for a computer game can easily take over the whole CD ROM! (Which I would gladly do if they would ever let me.)
What are you supposed to have learned from all this tech talk? Digital recording is good stuff but it has its limitations. Carefully consider what kind of sound you are recording and how good you want it to reproduce versus the needs of your situation for speed and files sizes. A tip is to always record at the maximum possible resolution then try different settings for reducing the file size by reducing either the bits to 8 or the sampling frequency to 22.050 (kHz) or 11.025 or less until you get the right balance of quality and size. As you reduce the resolution you will lose higher frequencies but not low frequencies leading to an overall dull and bass-ey sound and adding hiss and noise. There are numerous tools that will allow you to reduce digital recordings as much as possible with the least lost of sound quality. Often how you reduce the resolution is as important as amount of reduction you choose.
Making Music using MIDI and Digital Audio
There are many programs available for both Macs and PCs that allow you to compose, record, play back and print music in a variety of ways using MIDI and Digital Audio together. They can range from under well under $100 to over $800. They have a surprising variety approaches to the same problem and if has been my experience that none of them is without glaring flaws. Some, however; are excellent in spite of those flaws while others are just mediocre and flawed beyond comprehension. Most of the best programs are available at prices between $200 and $450 street price and I have found that I always need two complimentary programs to do everything I want to do. Make plans in your budget to eventually purchase a second or even third program as your skills improve and you develop a better idea of what features you will need. It is best to start with some research and try to get a program that has a good variety of capabilities (you may indeed need most of them right away) without being too complicated. It is hard to learn a whole new technology while still learning more about music while also trying to learn to compose and record music while wrestling with an overly complicated interface. It is also tragic when a beginner buys a cheap program thinking that it will be easier to learn not realizing that better programs best feature is how they lay things out logically and make everything more accessible. The beginner then gives up thinking MIDI is hard when the only real problem was badly conceived software. All software is written by programmers who tend to think at a very technical level and then convert that into a user interface instead of being a musician first, think of what would work best musically, designing an appropriate interface, THEN designing the code modules to back it up. Ask lots of questions until you are comfortable and don't expect everything to make sense immediately. MIDI is a whole new skill. I had to take time out of music for a year or two to feel comfortable working in this new medium but the results have been tremendous and I would never go back.
Although this is the first article on this site it will also probably turn out to be the largest. If you decide to take the plunge you can be assured the you will find more detailed articles on MIDI, digital audio, and the creative muse as well as reviews of hardware and software and my favorite tips. Feel free to submit questions by clicking on the address at the bottom of the page. Whether I answer your question at all or answer it with an email or with a whole article (in which case I will email you a notice when it is finished) and in what time frame the answer comes will depend on the relevance of the question to the focus of this site, whether it has already been answered in an article on this site, whether I have enough free time from composing, sound design and consulting to answer it promptly, and lastly, whether or not I can find out the answer my self. If I can find the information on another site I will post the name of the site and may establish a link to it.
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