What is General MIDI

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What is General MIDI

Post by exxos » Fri Jan 12, 2018 9:28 pm

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The General MIDI (GM) standard has been with us for a number of years now, and many people do not give it a second thought, bypassing the sound set for whatever else their keyboard or synthesizer of choice offers. Indeed, many systems have stopped offering the GM sound set, or have demoted it to an arbitrary sound bank for use with MIDI files bought off the internet for entertainers to use in holiday camps. Which is a shame as it reduces the format to a disposable set of sounds that it is perceived that no one uses.

This in part is true, but more due to lack of imagination and a misunderstanding of the sound sets purpose, caused in part by the industry that wanted the idea in the first place.

During the late 80's and early 90's, MIDI had become the standard for music communication and was available to the home enthusiast, right through to the very top of the professional music creators. Within the space of a few years it had swept aside all of the older incompatible standards that had gone before. The problem was that someone taking a song file to a friends house (Or a professional studio) would have trouble playing that song on a friends (Or a studio's) equipment if they did not have the same or a similar equipment setup. Most manufacturers had their own sound sets in different locations to one another and there was no common format or standard shared between them. Indeed different instruments from the same manufacturer would often have different sounds in different memory locations, making transferring songs between setups a potentially long and tedious process.

Users made their thoughts known and the manufacturers got together to discuss a standard as they did in the early 80's when they conceived the original MIDI specifications. After a while they agreed on what would become known as the General MIDI standard.

The idea was to have similar sounds in the 128 specified locations in the MIDI specification and a minimum number of notes that could be played (Which was 24 notes) and pre-set options for digital effects, so it did not matter who manufactured the keyboard or sound module, you would have a similar sound when you played your track, assuming you had composed it on a general MIDI device and was played back on another one.

But... What if you wanted more sounds?

Well, MIDI has always had the ability to adapt and has had gaps in its command lists for command extensions, A bank switch command was introduced so that you could select more than 128 sounds, so the GM soundset can be bypassed if you want to get to your systems more exotic sound sets.

But how did they come to agree on the sounds?

Well, they didn't really, various suggestions were put forward and Yamaha had tried to preempt the standard by creating one of their own in their Yamaha PSS and PSR series of keyboards (See the Yamaha PSS-680 retro review for Yamaha's proposed list of sounds) but the governing body for the MIDI standard decided that the default voice list from the Roland MT-32 would be the best fit for the General MIDI spec, with a few alterations.

Not many companies were happy with this, not even Roland, but this is what the initial standard was based on, a synthesizer module that had been out of production for nearly 4 years at that point in time. Begrudgingly it was accepted and put onto home keyboards and some professional synthesizers, though the synthesizers, but quite often the sounds used were dull and varied in quality from manufacturer to manufacturer, sometimes from device to device from the same manufacturer. This was not good for the GM standard and it seen got a bad reputation and became the butt of many musician jokes.

This wasn't really fair though as many devices had some high quality GM sound sets, but the one claim that GM could not defend itself against was that it stifled sound and music creativity, why would someone create their own sounds or music when they could effectively get pre-packaged modules and floppy disks with pre-composed music? Again in fairness, the fist argument could be leveled against most synthesizers of the time. Many still had their pre-set sounds installed when they were sold on as the user had either no need, no time or did not know how to create their own sounds. The second argument though could be heard in holiday camps and clubs throughout the world as second rate singers relied on cheap GM sound modules and pre-bought collections of the current hist to provide lackluster performances of various chart hits.

Roland though decided to think a little different and provided the XG extension to the GM standard, providing additional banks of sounds with similar groupings to the existing standard, and provided this on their Sound Canvas range of sound modules. This re-invigorated the GM sound module market to the point that Yamaha did a similar thing, providing additional banks of sounds that both complemented and expanded the GM sound set. Welcome as these innovations were, it was bringing the MIDI world back full circle where sound sets on different systems were different and songs were difficult to transfer between different machines. Worse still, some sequencers still did not support bank switching fully, so users would have to do switching from their modules front panels or just stick with the GM sounds and hope they were a pretty good set, while wasting up to 2/3 of the sound library the machine offered.

by the late 90's though, most of these issues had been fixed, the overall quality of sounds had improved and most soundcards supported the format, allowing the humble PC or Mac to become a GM instrument. On the soundcards though, the GM sound sets could be supplemented or replaced by soundfonts, which were a library of sounds that were either available for free, or could be purchased from companies such as Creative Labs. Even the Atari Falcon had software written for it to turn it into a GM compatible sound module, and by all accounts the sound quality was pretty good.

But the format was still the same as it was when it was first defined, and pretty much the same as it was in 1987 with the Roland MT-32. So in time for the new millennium, a new enhanced General MIDI specification was proposed, General MIDI 2, the imaginatively named sequel.

Well, that was the plan.

GM2 has not won many followers, at least in the high end synthesizer market, though it does sometimes feature on some home keyboards. GM does still show up from time to time, though it's importance has waned as the software studio has taken hold.

There are some notable GM keyboards which went beyond the basic specification and provided a wealth of sounds and features, for example Yamaha's excellent DJX series which took the sound generator of the CX-1 and placed it into a home keyboard with tweakable filters and assignable ribbon controller.

General MIDI was a good idea in principle, but had its roots too far in the past. The world had moved on from the MT-32 by the time the specification had been decided, never mind brought to market, but the principles and idea's behind it were sound, it was the execution that initially failed it as there were no guidelines governing the quality of the sound set, just what sound should go where. The spawning of the General MIDI files market, reducing hit records to the lowest common denominator of sounds didn't help the formats image and sometimes had the unfortunate side effect of making competent performers sound less professional than they really were, depending greatly on the instrument they used and how much time they spent customising the files to their own performance.

While many derided the format in the more professional music press, many people did use the format and when used properly on some of the better quality systems, it did was capable of producing a full professional sound. It was even possible to buy GM sound sets to make the Roland MT-32 and its more professional cousins, the D-10, D-20 and D-110 GM compatible.

Below is the overall governing format for the General MIDI standard, showing the groupings, the sound list and the rhythm section definition.

gm.png (401.67 KiB) Viewed 1200 times
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