diff util/matlab_midi/writemidi.m @ 81:a30e8bd6d948

matlab_midi scripts

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/util/matlab_midi/writemidi.m	Mon Mar 28 17:35:01 2011 +0100
@@ -0,0 +1,143 @@
+function rawbytes=writemidi(midi,filename,do_run_mode)
+% rawbytes=writemidi(midi,filename,do_run_mode)
+%
+% writes to a midi file
+%
+% midi is a structure like that created by readmidi.m
+%
+% do_run_mode: flag - use running mode when possible.
+%    if given, will override the msg.used_running_mode
+%    default==0.  (1 may not work...)
+%
+% TODO: use note-on for note-off... (for other function...)
+%
+
+% Copyright (c) 2009 Ken Schutte
+% more info at: http://www.kenschutte.com/midi
+
+
+%if (nargin<3)
+do_run_mode = 0;
+%end
+
+
+% do each track:
+Ntracks = length(midi.track);
+
+for i=1:Ntracks
+
+  databytes_track{i} = [];
+  
+  for j=1:length(midi.track(i).messages)
+
+    msg = midi.track(i).messages(j);
+
+    msg_bytes = encode_var_length(msg.deltatime);
+
+    if (msg.midimeta==1)
+
+      % check for doing running mode
+      run_mode = 0;
+      run_mode = msg.used_running_mode;
+      
+      % should check that prev msg has same type to allow run
+      % mode...
+      
+      
+      %      if (j>1 && do_run_mode && msg.type == midi.track(i).messages(j-1).type)
+%	run_mode = 1;
+%      end
+
+
+msg_bytes = [msg_bytes; encode_midi_msg(msg, run_mode)];
+    
+    
+    else
+      
+      msg_bytes = [msg_bytes; encode_meta_msg(msg)];
+      
+    end
+
+%    disp(msg_bytes')
+
+%if (msg_bytes ~= msg.rawbytes)
+%  error('rawbytes mismatch');
+%end
+
+    databytes_track{i} = [databytes_track{i}; msg_bytes];
+    
+  end
+end 
+
+
+% HEADER
+% double('MThd') = [77 84 104 100]
+rawbytes = [77 84 104 100 ...
+	    0 0 0 6 ...
+	    encode_int(midi.format,2) ...
+	    encode_int(Ntracks,2) ...
+	    encode_int(midi.ticks_per_quarter_note,2) ...
+	   ]';
+
+% TRACK_CHUCKS
+for i=1:Ntracks
+  a = length(databytes_track{i});
+  % double('MTrk') = [77 84 114 107]
+  tmp = [77 84 114 107 ...
+	 encode_int(length(databytes_track{i}),4) ...
+	 databytes_track{i}']';
+  rawbytes(end+1:end+length(tmp)) = tmp;
+end
+
+
+% write to file
+fid = fopen(filename,'w');
+%fwrite(fid,rawbytes,'char');
+fwrite(fid,rawbytes,'uint8');
+fclose(fid);
+
+% return a _column_ vector
+function A=encode_int(val,Nbytes)
+
+for i=1:Nbytes
+  A(i) = bitand(bitshift(val, -8*(Nbytes-i)), 255);
+end
+
+
+function bytes=encode_var_length(val)
+
+binStr = dec2base(round(val),2);
+Nbytes = ceil(length(binStr)/7);
+
+binStr = ['00000000' binStr];
+bytes = [];
+for i=1:Nbytes
+  if (i==1)
+    lastbit = '0';
+  else
+    lastbit = '1';
+  end
+  B = bin2dec([lastbit binStr(end-i*7+1:end-(i-1)*7)]);
+  bytes = [B; bytes];
+end
+
+
+function bytes=encode_midi_msg(msg, run_mode)
+
+bytes = [];
+
+if (run_mode ~= 1)
+  bytes = msg.type;
+  % channel:
+  bytes = bytes + msg.chan;  % lower nibble should be chan
+end
+
+bytes = [bytes; msg.data];
+
+function bytes=encode_meta_msg(msg)
+
+bytes = 255;
+bytes = [bytes; msg.type];
+bytes = [bytes; encode_var_length(length(msg.data))];
+bytes = [bytes; msg.data];
+