src/midi.h

   1 /*
   2    Epichord - a midi sequencer
   3    Copyright (C) 2008  Evan Rinehart
   4
   5    This program is free software; you can redistribute it and/or
   6    modify it under the terms of the GNU General Public License
   7    as published by the Free Software Foundation; either version 2
   8    of the License, or (at your option) any later version.
   9
  10    This program is distributed in the hope that it will be useful,
  11    but WITHOUT ANY WARRANTY; without even the implied warranty of
  12    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13    GNU General Public License for more details.
  14
  15    You should have received a copy of the GNU General Public License
  16    along with this program; if not, write to
  17
  18    The Free Software Foundation, Inc.
  19    51 Franklin Street, Fifth Floor
  20    Boston, MA  02110-1301, USA
  21 */
  22
  23 /* midi junk
  24
  25 notes on timing
  26 the sequencer will use some number of ticks per beat which
  27 corresponds to its minimum allowed note length.
  28
  29 a beat is divided into four parts at the regular zoom.
  30 in 4/4 time this corresponds to 1/16 notes.
  31 lets make the shortest note 1/TICKS_PER_BEAT note.
  32 this means there are TICKS_PER_BEAT 'ticks' per beat.
  33
  34 to convert from time in us into ticks do
  35
  36 ticks = time * BPM * TPB / (1000000 * 60);
  37
  38
  39 */
  40
  41 #ifndef midi_h
  42 #define midi_h
  43
  44 #define MIDI_NOTE_ON 0x90
  45 #define MIDI_NOTE_OFF 0x80
  46
  47 //encodes data in e as a midi event placed in buf
  48 int midi_encode(mevent* e, int chan, char* buf, size_t* n);
  49
  50 //decodes midi data and creates a new mevent
  51 int midi_decode(char* buf, mevent* e);
  52
  53 #endif