[linux-audio-dev] Basic MIDI question

[Lars Luthman]

On Mon, 2006-07-24 at 16:38 -0400, Lee Revell wrote:
> I've never been a MIDI expert but I'm now having to learn.  I have a
> question about this excerpt of a MIDI file viewed with hexedit.
> 
> 00001BB0   22 80 3D 35  31 80 3A 39  0E 80 37 31  03 80 31 1F  ".=51.:9..71..1.
> 00001BC0   81 0C 90 30  5B 00 90 3C  79 81 70 90  39 73 00 90  ...0[..<y.p.9s..
> 00001BD0   36 69 4B 80  36 43 0A 80  3C 26 01 80  30 44 0A 80  6iK.6C..<&..0D..
> 00001BE0   39 42 82 08  90 37 63 00  90 43 7B 81  70 90 3E 5E  9B...7c..C{.p.>^
> 00001BF0   00 90 3A 66  08 80 37 30  02 80 43 32  31 80 3E 11  ..:f..70..C21.>
> 
> Take the sequence "80 3D 35  31 80 3A 39  0E 80 37 31  03 80 31 1F" in
> the first line for example.  I know that 0x80 is note-off, and 0x3D are
> note number and 0x35 the velocity of the note-off.  But what the heck is
> the next byte, 0x31?  The MIDI standard says note-off is one status byte
> followed by 2 data bytes!

That's the standard for MIDI that is sent realtime over a wire. When it
is stored in a file you also need some sort of timestamp for each event.
The extra byte is the number of clock ticks to wait before you play the
event (since the last event).

-- 
Lars Luthman - please encrypt any email sent to me if possible
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