note

So your midi controller sends notes and controls on channels to a sound module.
What EXACTLY is a note then...?

Each time you press or release a key on your controller, a little "event" is
sent across the midi wire containing the note info.
Let's say you played a c major chord and held it for a second.
The activity on the midi cable would look something like this:

   1 4c Down 100
   1 4e Down  98
   1 4g Down  98
   ...a second goes by with no activity...
   1 4c Up    64
   1 4g Up    64
   1 4e Up    64

   - channel:
     1 means you used channel 1 and the sound for the chord will be whatever
     sound is assigned to channel 1.  Probably piano.

   - note:
     4c means octave 4 note C (middle C)

   - Down/Up:
     Down means the key was pressed.
     You get a seperate event with "Up" when the key is released later.

   - velocity:
     100 is the "velocity" - how fast (or hard) the key was pressed.
     1   for VERY softly - probably no sound.
     127 for banged on as HARD as possible - loud!
     Some keyboards also give a velocity on the key up event.
     Some just always set it to 0 or 64.


Note that...
   in this example, you pressed the C note a little harder than the
   other 2 in the chord.
   Also note that you let up on the G a little earlier than the E.
   Possibly by a few microseconds.  Midi timing is usually VERY precise.


Time too:
   When these note down (note on) and note up (note off) events are stuffed
   into a file, the exact time that EACH event happened is stuffed in too.
   This let's a midi sequencer (a music program) repeat your EXACT performance.


Really exact?
   Well, some would argue that this isn't an EXACT replication since your
   keypresses are turned into 1..127
   Not the possibly more subtle velocities YOU are capable of.
   But, well, I'll let you decide about that.
   To me, 1..127 seems pretty dang dead on.


Octaves:
   Synth manufacturers often don't agree on how to number octaves.
   =I= use the most standard convention I've come across...
      middle C's octave is 4.
      Note that octaves start at 0.
      And this full octave of notes isn't available on your garden variety
                                                                88 key keyboard.
   Just be careful reading octave numbers in the docs for your synth.


How midi compares to sheet music:
   Midi is "super sheet music" - an EXACT performance of a song.
   Sheet music doesn't go down to EXACT timing.
   It also doesn't specify EXACTLY how hard to press and release each note.
   There are timing and dynamics markings on sheet music, but these are pretty
      general and left up to you for an actual interpretation.

   So a midi file can specify EVERYTHING that sheet music does.
   but fortunately and unfortunately, it's tough to convert this "performance"
   back to sheet music.  Sheet music shows notes in "perfect durations".
   You may want to play the note a bit earlier than when the metronome clicks.
   And you may want to play legato or stacatto - different durations.

   You want your performance to be expressive, not just an exact match to the
                                                                    sheet music.
   Often, you'll have ONE midi file of "just the sheet music" to learn.
   And ANOTHER midi file of your performance with "expressive" notes.

Next up, drum notes