MSB & LSB applications

“Through reading various publications I have gained a pretty good understanding of MIDI. One of my last areas of question pertains to MSB/LSB. I understand that they are used in tandem to create a greater number of variations of a given parameter, however is there any occasion where I might utilize them? Can you give me an example to illustrate?” For a thorough explanation we went to our Director of Soundware Engineering, Daniel Fisher. He says:As you’ve probably already learned, most MIDI Control/Note data is described with values between 0 and 127. This provides fairly good resolution as it can describe notes beyond either end of an 88-note keyboard and can also make reasonably smooth real time changes in Volume, Pan, Timbre, Vibrato Rate/Depth, etc.But one aspect of music where your ears are particularly adept is the detection of subtle changes in Pitch (Frequency). In fact your ears are so good at it that they can hear the stair-stepping that occurs as a Pitch Bent note bends upwards or downwards across one whole step (And, if your Pitch Bend Range is +/- One Octave, it’s painfully obvious).To satisfy your ears’ pitch sensitivity it was decided to break each individual segment of Pitch Bend into an additional 128 little steps. This now provides 128 x 128 steps of resolution (16,384 steps) which results in a smoother, more natural Pitch Bend.How do you utilize this? That’s easy… just move the Pitch Bend Wheel. You’ll automatically be sending both MSB (Most Significant Byte) and LSB (Least Significant Byte) information. Low-cost synthesizers may only read the MSB thus giving you only 128 distinct values. Better synths will apply both the MSB and LSB to Pitch Bend giving you 16,384 steps.The official MIDI Spec has set aside LSB values for Continuous Controllers ranging between CC#0 to CC#31 (which are themselves used as MSB values). The LSB values for those are defined by the value of CC#32 through CC#63. These are paired off like: CC#0 = MSB & CC#32 = LSB, CC#1 = MSB & CC#33 = LSB, etc.For now, there’s not much you can do with this if your Controller doesn’t send LSB or if your synth doesn’t receive LSB on Continuous Controllers. The one exception is CC#0/CC#32 which is Bank Change MSB/LSB.Unfortunately, each synth company independently interpreted which CC# was MSB and which CC# was LSB. So now most synths just listen to both CC#0 and CC#32 and pretend both of them are MSB for Bank Change (a.k.a. Bank Select). This will cause problems in the future someday when synths have hundreds of Banks. (Maybe they’ll learn from the Y2K problems…).Ed – For more info on bank change commands and issues check out the following TTOTD from the archives.http://insync.sweetwater.com/ttotd/06-18-98.html§http://insync.sweetwater.com/ttotd/07-01-98.html§http://insync.sweetwater.com/ttotd/07-02-98.html§http://insync.sweetwater.com/ttotd/03-16-99.html

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