TxtData=\f002 You've heard multimedia computers sound like a symphony orchestra or even a rock 'n roll band...but how do they do it? \par To help you understand, we've created this notebook of computer music history, complete with explanations and examples of how your computer makes music.
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TxtData =\f002 Your PC can make music in three different ways: \par\par 1. You can play an \ATXht1\cf5\f001 Audio CD \ATXht0\plain\f002 in your CD Player. \par\par 2. You can play a \ATXht2\cf5\f001 Digital Audio Wave File \ATXht0\plain\f002. \par\par 3. You can play a \ATXht3\cf5\f001 MIDI Sequencer File \ATXht0\plain\f002. \par\par No matter which method you choose, you also have to \ATXht4\cf5\f001 Hear It \ATXht0\plain\f002 somehow.
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TxtData=\f002 Playing an audio CD on your \ATXht150\cf5\f001 CD-ROM\ATXht0\plain\f002 player can be as simple as pressing the play button on the software that your CD manufacturer included with the unit. \par This is sometimes a full-fledged version of a computer stereo system, complete with mixers, volume controls and controls for \ATXht145\cf5\f001 CD Audio \ATXht0\plain\f002, as well as \ATXht305\cf5\f001 MIDI \ATXht0\plain\f002 and \ATXht210\cf5\f001 digital audio \ATXht0\plain\f002 playback.
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TxtData=\f002\ATXht210\cf5\f001 Digital Audio\ATXht0\plain\f002 exists on your computer in files with the extension \ATXht600\cf5\f001 WAV \ATXht0\plain\f002... this stands for "wave file." \par All sound that you hear exists as sound waves traveling though the air. From the plucked string of a violin to the human voice, sound is made of groups of \ATXht605\cf5\f001 waveforms\ATXht0\plain\f002 superimposed upon each other and transmitted through the air.
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TxtData=\f002 When you record a live sound into your computer, your sound card is actually converting the sound waves into digital information. This is called \ATXht120\cf5\f001 Analog to Digital Conversion\ATXht0\plain\f002. \par When you play that WAV file back again, your sound card does the exact opposite, converting \ATXht215\cf5\f001 Digital to Analog\ATXht0\plain\f002.
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TxtData=\f002 MIDI (Musical Instrument Digital Interface) is a language your computer uses to play music. MIDI lists the order (sequence) of notes and rests in the music, as well as what instruments should play those notes. \par Your sound card receives the MIDI information and then synthesizes the sound waves for these notes.
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TxtData=\f002 Depending upon your sound cardÆs synthesis technique, sound quality can range from pretty great to pretty awful. \par Currently, wavetable sound cards and modules offer the best synthesis technique for converting MIDI data into sound, while older FM synthesis cards often produce instrumental sounds that are less than ideal.
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TxtData=\f002 Once your card has processed the appropriate type of sound, the analog electrical signals are sent to small output plugs that fit a pair of headphones. \par Some cards have a built-in amplifier that can drive a small pair of speakers, but in most cases youÆll need speakers that have their own amplification. \par Optionally, you can use adapter plugs to route your sound cardÆs output through your home stereo system for a really full sound.
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TxtData=\f002 But how can you make music with the computer? \par How does MIDI connect to your PC? \par How can you say something and have the computer play it back?
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TxtData=\f002 ItÆs pretty easy to record your own \ATXht600\cf5\f001 WAV\ATXht0\plain\f002 files to the hard disk. To start with, youÆll need to connect a microphone (or any other line device like a tape deck or electric guitar) to the \ATXht295\cf5\f001 microphone plug\ATXht0\plain\f002 (or auxiliary plug) on your sound card. \par Windows 3.1 and Windows 95 come with a recording utility called Sound Recorder. This program allows you to record directly to the hard disk. There are many other advanced programs that give you added functionality.
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TxtData=\f002 When you do digital recording youÆll find that the quality of your wave file depends upon two factors: the \ATXht485\cf5\f001 sample rate\ATXht0\plain\f002 and the \ATXht140\cf5\f001 bit resolution\ATXht0\plain\f002. \par The sample rate tells you how many digital recordings of the sound are taken each second -- higher rates yield more accurate recordings. The bit resolution tells you the level of detail of each sample -- the higher the resolution the better the sound. \par Watch Out! WAV files can be very large, taking up as much as 10 Mb per minute at CD quality recording levels.
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TxtData=\f002 Then thereÆs that MIDI keyboard you might own... how does that hook up? \par MIDI \ATXht280\cf5\f001 keyboards \ATXht0\plain\f002 and devices have their own special style of connections, so to hook these pieces into your PC youÆll need a \ATXht325\cf5\f001 MIDI Interface\ATXht0\plain\f002.\par Your sound card usually has a \ATXht255\cf5\f001 Game Port \ATXht0\plain\f002 that can be adapted to a MIDI Interface using a simple cable system and a \ATXht505\cf5\f001 software driver\ATXht0\plain\f002 . These are available from your sound card manufacturer or other third-party sources.
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TxtData=\f002 Once you have your interface hooked up youÆre ready to record your musical ideas via MIDI. This means using a sequencing program of some type.\par \ATXht495\cf5\f001 Sequencers\ATXht0\plain\f002 can be used to record your keyboard playing. They use the large number of sounds available on your sound card to reproduce your music. If your sound card is \ATXht260\cf5\f001 General MIDI\ATXht0\plain\f002 compatible, then youÆll have 128 different instruments to choose from as well as many different percussion sounds.
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TxtData=\f002 For those of you interested in the full extent of your PCÆs capabilities, thereÆs a whole world of MIDI devices and programs that can be run from your computer once youÆve gotten your interface set up. \par \ATXht220\cf5\f001 Drum machines \ATXht0\plain\f002 , \ATXht615\cf5\f001 wind controllers \ATXht0\plain\f002, \ATXht265\cf5\f001 guitar controllers \ATXht0\plain\f002, specialized sound modules, \ATXht380\cf5\f001 multi-port interfaces \ATXht0\plain\f002, and \ATXht455\cf5\f001 programmable mixers \ATXht0\plain\f002 just scratch the surface of the possibilities with MIDI and your PC.
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TxtData=\f002 MIDI (Musical Instrument Digital Interface) is a recent innovation in the world of electronic music. Electronic music has been around since the end of the 19th century with the development of the first vinyl recordings. What we now know as electronic music evolved from the ability to play new and unique sounds via synthesizers. \ATXht550\cf5\f001 Synthesizers \ATXht0\plain\f002 created new sounds from standard \ATXht605\cf5\f001 waveforms\ATXht0\plain\f002. But they were tricky to set up and change around, and they couldnÆt communicate very well with other synths.
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TxtData=\f002 Musicians were using synthesizers to create new electronic sounds, but they also wanted to be able to record, play back and change their music 100% electronically. \par Synths basically pushed around electrical signals, so when someone played a piece of music, musicians recorded the order (sequence) of electrical signals going on inside the synth. To repeat the music, all they had to do was reproduce those exact electrical signals again, in sequence. To play the music backwards, they merely had to produce the sequence of signals backwards. \par Electrical signal languages, which translated musical symbols into synth signals, developed in this fashion.
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TxtData=\f002 MIDI evolved in response to a whole industry of manufacturers who developed very different languages for electronic music. With different languages, a sequence that was recorded on one manufacturerÆs synth often sounded stiff, unmusical, or just plain wrong on a different manufacturerÆs equipment. \par MIDI set the standards by which electronic music was transmitted from machine to machine, synth to synth, sequencer to sequencer. Music would always record and play back the same way.
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TxtData=\f002 LetÆs explore what a MIDI sequence looks like using a simple piece of music... "Row, Row, Row Your Boat". \par One instrument starts playing "Row, Row, etc..", then two measures later another instrument starts the tune, and so on. \par Each of the four different melodies would be placed on a different \ATXht575\cf5\f001 track \ATXht0\plain\f002 in the sequence. This track would be like the music for that melody. Contained within each track is a record of what notes were played when.
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TxtData=\f002 To get each of these four tracks to play on a different instrument, youÆd have to assign them each to a different MIDI \ATXht155\cf5\f001 channel \ATXht0\plain\f002. \par The \ATXht260\cf5\f001 General MIDI \ATXht0\plain\f002 convention allows for the use of 16 channels simultaneously. With each channel playing a different instrument, itÆs like having a small orchestra playing.
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TxtData=\f002 Suppose that you wanted to have a Drum Kit (Bass Drum, Snare, High Hat, Ride Cymbal, Crash Cymbal, and Snare with Brushes) banging along with your song,"Row, Row". \par These percussion instruments are not included in the 128 General MIDI instruments. General MIDI handles non-pitched percussion in a special way -- it reserves Channel 10 for them. Any tracks which are set to Channel 10 play percussion sounds. \par You can put each part of the kit in a separate track, or put them all together into one track. Just make sure that theyÆre set to Channel 10 or you wonÆt hear the drums.
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TxtData=\f002 But music calls for much more than just a series of notes and rests. How about how loud or soft the music is? How about different types of sounds from the same instrument ("pizzicato" or "tremolo" in the strings)? How about bending the pitch? MIDI is designed to capture many of these musical subtleties through the use of values for \ATXht415\cf5\f001 parameters, \ATXht180\cf5\f001 controllers \ATXht0\plain\f002 and \ATXht425\cf5\f001 patch changes\ATXht0\plain\f002. \par For example, how loud or soft a note is in MIDI is determined by a \ATXht580\cf5\f001 velocity \ATXht0\plain\f002 value. If the note gets louder or softer as it holds, then these are recorded as \ATXht175\cf5\f001 continuous controller \ATXht0\plain\f002 changes. Another type of continuous controller can track pitch bending. In the case of changing instrument sounds, you can place a patch change within any track at any time.
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TxtData=\f002 As you advance, you might want to incorporate your MIDI work into more professional recordings. \par YouÆll need to \ATXht545\cf5\f001 synchronize \ATXht0\plain\f002 your MIDI song to \ATXht500\cf5\f001 SMPTE \ATXht0\plain\f002 if you plan on using \ATXht195\cf5\f001 DAT \ATXht0\plain\f002 machines, video editors, and other similar equipment. \par A slightly different approach of high-end sequencing programs is to give the sequencer both digital and MIDI capabilities. Then you can have a complete recording studio in one package.
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TxtData=\f002 This is the complete General MIDI Instrument list. Any of these 128 instruments may be used on Channels 1 through 9 and 11 through 16.
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TxtData=\f002 In General MIDI, any channel can play one instrument at a time, except Channel 10. It can play 47 different instruments at the same time -- the non-pitched percussion instruments. \par Each of these 47 instruments is assigned to a specific note.The diagram details the General MIDI percussion patch map on a standard keyboard. \par Note that Middle C is marked for your reference; it plays a Middle C on any channel except Channel 10, where it plays a Hi Bongo drum.
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TxtData=\f002 What is synthesis? \par The word comes from the Greek word meaning "to put together." \par Plants use photosynthesis. They convert sunlight into energy using chlorophyll, and combine that energy with nutrients in the soil to make their food. \par In music, synthesis refers to the creation of complex sounds from simpler sounds.
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TxtData=\f002 Sound is really just a bunch of waves being carried to our ears through the air. One way to think of it is as ripples on a pond. When you throw a stone into the pond it creates waves, which carry across the water to the shore. \par \ATXht515\cf5\f001 Sound waves \ATXht0\plain\f002 come in many varieties and shapes. The sounds you hear every day are extremely complex waveforms \ATXht0\plain\f002 made up of many \ATXht570\cf5\f001 tones \ATXht0\plain\f002 and \ATXht410\cf5\f001 overtones\ATXht0\plain\f002.
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TxtData=\f002 In the middle of the 20th century musicians invented synthesizers to literally put together musical sounds. \par Synthesizers use a technique called \ATXht100\cf5\f001 additive synthesis\ATXht0\plain\f002, creating complex \ATXht605\cf5\f001 waveforms \ATXht0\plain\f002 by adding together many simpler waveforms. The simple waveforms are produced by small tone generators called \ATXht200\cf5\f001 digital controlled oscillators\ATXht0\plain\f002. The synthesizer then repeats these waveforms for as long as the note should last. \par Sound synthesis has come quite far and modern synths can produce instrumental sounds with remarkable accuracy.
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TxtData=\f002 PC sound cards have built-in synthesizers. The standard PC sound card uses \ATXht240\cf5\f001 FM synthesis\ATXht0\plain\f002, just like a synthesizer, to produce its sounds. \par Basic SoundBlaster-compatible cards have only 3 or 4 digital oscillators creating all of their sounds. This can be limiting to the musical quality of what you hear because real musical instruments produce very rich waveforms, more complex than can be synthesized using oscillators.
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TxtData=\f002 A more advanced method of sound synthesis is called \ATXht610\cf5\f001 wavetable synthesis\ATXht0\plain\f002. \par Wavetable synthesis begins by taking a digital recording of an instrument. A small portion of this recording is selected and set to be the \ATXht478\cf5\f001 sample \ATXht0\plain\f002 . This sample is similar to the complex waveforms created using oscillators in FM synthesis but is much more accurate. The sample is then repeated, or \ATXht290\cf5\f001 looped\ATXht0\plain\f002, for as long as the sound should last.
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TxtData=\f002 Wavetable synthesis exists on many expensive sound cards. These cards include memory chips which hold the megabytes of memory needed for of the samples and processors to provide the computing muscle to move these samples quickly. \par Another approach has been to use the incredible power of the Pentium« processor to handle this workload. This is available from many vendors in a technique called \ATXht508\cf5\f001 software wavetable synthesis.\ATXht0\plain\f002.
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TxtData=\f002 Software wavetable synthesis brings the quality of wavetable instruments to your computerÆs motherboard. This means superior sound and savings for the consumer. \par But donÆt just take our word for it, hearing is believing!
