Computer-Music.com contains articles and product reviews related to making music using 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 sound effects. For pricing and contract availability send email to: DGriffin (@) Computer-Music (.) com

Computer-Music.com  contains articles and product reviews related to making music using 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 sound effects. For pricing and contract availability send email to: DGriffin (@) Computer-Music (.) com



 

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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'. When I wrote this in 1996 I said "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." Since then things have changed somewhat. Most games come on a CDROM which holds about 650 megabytes of data or roughly 65 minutes of 'CD quality' music. Unfortunately a single CDROM will not hold both 650 megabytes of game data and an additional 650 megabytes of music 'Red Book' CD music. In game development there have always been battles between audio people and graphics people. Usually the the audio guy gets the left-over space on the disc. Today's high speed, high memory, graphics cards and PCs with more memory have allowed games to include more and larger textures and 3D objects with more and more polygons. This continues to pressure the audio people to take less space on the CD. Because of this CDROM use has not exactly freed up game audio to be simply CD audio. Instead there has been an ebb and flow greater space becomes available to audio people temporarily, only to be taken away by the unending hunger the graphics department. While description of the various techniques currently used to make better game audio is beyond the scope of this article, I can say that MIDI is just as important as it ever was at least in the development of game audio and often in its execution during game play. For those not interested in computer games you may be surprised that MIDI has not lost any of its popularity in the give years sine I first wrote this article. It is simply being used in more and more complex ways.

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. In 1995 I said "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." Today backward compatibility consists primarily of some sort very basic General MIDI synthesizer using sampled audio rather than FM synthesis. This capability is either a chip on the motherboard or part of your sound card. I think I can safely say that the low quality $18 FM chips used in the older sound cards are officially dead. However, higher quality implementations of FM synthesis are still quite viable and useful components of many modern music studios. In addition, with today's faster CPUs you can often settle for a software-based synthesizer which only needs a sound card (or sound support built onto your motherboard) with simple audio output. Software based synthesizers are simply computer code running in your CPU but they share memory CPU load with all of your other programs so you may not want to go this route if you need every bit of CPU power for fast game play. Another downside for software synthesis is that there is usually a greater delay than with hardware synthesis. The time between when you press a note on your keyboard and when you finally hear it from your speakers. This should eventually become a moot point with faster computers and sound cards. 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 than one relying on a software synthesis program because generating music on your sound card will not slow down your CPU. For a while many sound cards had 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. This was because FM was still considered a basic MIDI capability while sample based or 'wave table' synthesis was considered an extra. Since then sample based synthesis is considered a basic feature and any card with daughter card support would provide this so you could add some kind of special capability such as a physical modeling synthesis card or an effects unit (Reverb and Chorus). As of this writing the 'SoundBlaster Live!' card from Creative Labs seems to be the most generally useful card for gamers and basic music work. It is quite a bit better in audio quality than preceding generations of cards from this company so you should not automatically discount it as being of low quality based on what you heard in the past. Today other companies also offer quite good sound cards at the consumer level because the technology to manufacture good quality circuits at an affordable price has finally arrived. This means that the 'professional' quality cards are not merely good, they are REALLY good. Since I originally wrote this article it has become a reality that you can have a professional quality music production suite built almost entirely within a single PC chassis or plugged directly in to it via USB and Fire Wire devices. All controlled directly from your software. What hardware is still outside the PC chassis often has digital audio inputs and outputs so it can handle passing data to and from the computer with not loss in quality. Reducing the number of components outside of the computer saves you lots of money because each of those components needs its own chassis, power supply, buttons carries with it greater development and shipping costs.

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 or loaded into RAM by the program. 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. To this I should add that lots of game audio now consists of music recordings produced in a music studio which may be played as a standard CD 'Red Book' audio track, or loaded into memory and played back as a compressed audio file like an MP3, or part of heavily compressed movie file. This causes the quality of even pre-recorded audio to vary quite a bit. Recent advances in interactive and algorithmic music technology are again requiring MIDI in order to handle music that changes from  moment to moment in response to changing game situations. Luckily this new age of MIDI is controlling software synthesizers with uniform sound from player to player so everybody hears the same quality that the designer intended. I am happy to say that modern computer users tend to go for somewhat better speakers. But I am saddened to say that even the best speakers intended for computer use tend to produce less than half of the quality of even a cheap home entertainment system. While most computer components get cheaper and cheaper via the rapid advances in chip technology, speakers benefit from this to a much lesser degree therefore higher quality speakers will continue to be expensive for the foreseeable future.

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. If you have a sound card like this then you can simply buy a MIDI In/Out cable that plugs into the sound card's joystick port and voila! you have a place to plug in your MIDI keyboard. However I am quickly seeing more and more audio functions being combined in increasingly powerful audio devices so you will likely end up buying at least one device that includes a better quality (lower latency) MIDI port as part of its Swiss-Army-Knife-like combination of features. For example, as of this writing, one company was still struggling to release a USB device that is a stand-alone 16 channel audio mixer, a 24 bit / 96 kilohertz digital audio interface, 2 high quality MIDI ports, (2-in/2-out) and a MIDI control interface. This unit includes both analog and SP/DIF digital audio connectors. But USB is effectively a narrower pipe than we would like to handle all this data so it is likely that the coming Fire Wire and later USB2 audio devices will be what the great numbers of computer music users will flock to.

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