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From: maverick@fir.Berkeley.EDU (Vance Maverick)
Newsgroups: sci.electronics,comp.music
Subject: Re: MIDI data compression idea
Keywords: MIDI
Message-ID: <8928@pasteur.Berkeley.EDU>
Date: 15 Nov 90 20:32:52 GMT
References: <1990Nov15.173346.11644@yenta.alb.nm.us>
Sender: news@pasteur.Berkeley.EDU
Reply-To: maverick@fir.Berkeley.EDU (Vance Maverick)
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> Aren't MIDI messages horrendously inefficient?  I seem to remember
> reading that normal note data, in order to be distinguishable from
> control messages, has to have the eighth bit turned off.  But the
> data is still logically grouped in eight-bit chunks, so you get
> something like this:
> 
> 0000xxxx
> 0000yyyy

No, note data is mostly 7 bits.  (Some other data, like bender values,
are 14 bits.)  For example, pitch and velocity both have range 0-127. 
So for most information, you're only "wasting" one bit in eight. 
Four-bit nibbles are used for status code (eight values, all with high
bit set) and channel numbers (a grossly inadequate sixteen).  And these
always share a byte, so it's pretty efficient on the whole.