www.gusucode.com > 声音的处理有：LPC，FFT，共振峰，频谱源码程序 > siganlandsystemusingMatlab/SSUM/physmodel/ksstring/midird3.m
function [midi,info,ext,ms_per_quarter,ms_per_tick] = midird3(fname,txtname)
% function [midi,info,ext,ms_per_quarter,ms_per_tick] = midird3(fname,txtname)
%
% This function reads Standard MIDI Files (SMFs) and returns their contents
% in the two structures midi and info.
%
% midi is a struct array containing one field for each track of the
% midi file. Within each field, the midi notes are given in
% the format
%
% (delta time,absolute time, midi note number, note duration, note velocity,
% channel)
%
% info contains all sideinfo from the header chunk as well as meter and time
% information from the MIDI meta events
%
% ext is all extended information besides notes contained in the MIDI file.
% This is needed, e.g., to reproduce the binary MIDI files
% using midiwr.m
%
% -> All system exclusive data are stored in ext
%
% Format of ext: (track abstime [binary MIDI sequence])
%
% ms_per_quarter milliseconds per quarter note, if indicated by
% MIDI-file (set to 0, if no information on time-coding is
% found in MIDI-file)
%
% ms_per_tick milliseconds per MIDI tick, if indicated by
% MIDI-file (set to 0, if no information on time-coding is
% found in MIDI-file)
%
% Inputs: fname Name of input MIDI-File
%
% (optional) txtname Name of Output-Textfile
%
% If the optional second argument txtname is used, a text
% version of the MIDI-file is written to a file named textname
%
% Changes: * Frank Kurth, Feb., 26th, 2004: Rework to cope with wrongly
% formatted SMFs
% * Andreas Ribbrock, Apr., 14th, 2004: Stabilized w.r.t. wrongly
% formatted SMFiles
% * Frank Kurth, May, 11th, 2004: Incorporated functionality to
% read time-coding from SMF (by Hinnerk Feldwisch and Meinard M黮ler)
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%%%%%%%%%% Last changes by Frank Kurth, May, 11th, 2004
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%
VLQLEN = 4; % Length of variable length quantities, currently == 4
TUPLEN = 6;
% The following are define global for use in the subfunctions within
% this file:
global smf;
global abstime;
%global ext;
%global extptr;
% some constants
UNDEF = -1; NOTEON = 0; NOTEOFF = 1; POLYAT = 2; CONTROLCHANGE = 3; PROGCHANGE = 4;
CHANNELAT = 5; PITCHWHEEL = 6; EXCEPT = 7;
% -fk 25.02.04
data = zeros(1,2);
% open input file
fid = fopen(fname,'r');
if fid < 0
disp(['midird3: Error opening MIDI file: ' fname]);
return;
end
% check if output file (MIDIasText) is requested
if nargin > 1
TXT = 1;
fidtxt = fopen(txtname,'w');
if fid < 0
disp('midird3: Error opening output file!');
fclose(fid);
return;
end
else
TXT = 0;
end
% read full MIDI file
smf = [fread(fid,inf,'uint8')' zeros(1,10)];
ptr = 1;
extptr = 1;
status = 255;
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%
% Read MIDI Track header
%
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
ptr = NextValidHeader(ptr);
if(ptr <0 | ptr+4 > length(smf) | ptr+7 > length(smf))
disp('Midi file format error on line 99 of midird3');
fclose(fid);
info = cell(0,0);
midi = cell(0,0);
ext = cell(0,0);
return;
end
len = Read32(smf(ptr+4:ptr+7));
ptr = ptr + 8; % 'MThd'
if(ptr <0 | ptr+1 > length(smf))
disp('Midi file format error on line 110 of midird3');
fclose(fid);
info = cell(0,0);
midi = cell(0,0);
ext = cell(0,0);
return;
end
info.format = Read16(smf(ptr:ptr+1));
if(ptr <0 | ptr+2 > length(smf) | ptr+3 > length(smf))
disp('Midi file format error on line 118 of midird3');
fclose(fid);
info = cell(0,0);
midi = cell(0,0);
ext = cell(0,0);
return;
end
info.ntrks = Read16(smf(ptr+2:ptr+3));
if smf(ptr+4) < 0
info.division.up = double(uint8(smf(ptr+4)));
info.division.low = smf(ptr+5);
info.division.main = inf;
else
info.division.main = Read16(smf(ptr+4:ptr+5));
info.division.up = inf;
info.division.low = inf;
end
if TXT
fprintf(fidtxt,'MIDI Header Chunk\n\n');
fprintf(fidtxt,'MIDI File Format: %d \n',info.format);
fprintf(fidtxt,'No. of Tracks: %d\n',info.ntrks);
if smf(ptr+4) < 0
fprintf(fidtxt,'Time Division: (%d,%d)\n',[info.division.up info.division.low]);
else
fprintf(fidtxt,'Time Division: %d\n',info.division.main);
end
end
ptr = ptr + len; % 32BitLength, the length should be 6 in SMFs
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%
% Read Tracks
%
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
midi = cell(1,info.ntrks);
abstime = 0;
for k = 1:info.ntrks
if(ptr < 1 | ptr > length(smf))
disp('Midi file format error on line 162 of midird3');
fclose(fid);
info = cell(0,0);
midi = cell(0,0);
ext = cell(0,0);
return;
end
ptr = NextValidHeader(ptr);
if(ptr < 1 | ptr > length(smf))
disp('Midi file format error on line 171 of midird3');
fclose(fid);
info = cell(0,0);
midi = cell(0,0);
ext = cell(0,0);
return;
end
ptrackstart = ptr;
if TXT
fprintf(fidtxt,'---------------------------------------------------------------------------\n');
fprintf(fidtxt,'MIDI Track Chunk #%d\n\n',k-1);
end
s = char(smf(ptr:ptr+3));
%s = sprintf('%s',smf(ptr:ptr+3))
if(~strcmp(s,'MTrk'))
s = sprintf('midird3: MTrk expected, %s found!',smf(ptr:ptr+3));
disp(s);
return;
end
tracklen = Read32(smf(ptr+4:ptr+7)); % track length
ptr = ptr + 8; % track start after header
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% start: process track
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
notes = zeros(tracklen,TUPLEN); % faster to create array at once
notepos = 1;
runningstatus.cmd = UNDEF;
runningstatus.channel = UNDEF;
actnotes = ones(1,TUPLEN)*-1;
uniqueID = -2;
if info.format ~= 2 % Note: abstime (here) is independent of the
abstime = 0; % time signature which is eventually
end % present in the MIDI file (Meta Event)
% abstime only counts delta ticks
while ptr <= ptrackstart + 8 + tracklen % start: track loop
if(ptr+VLQLEN-1 <0 | ptr+VLQLEN-1 > length(smf))
disp('Midi file format error on line 215 of midird3');
fclose(fid);
info = cell(0,0);
midi = cell(0,0);
ext = cell(0,0);
return;
end
if(ptr <1 | (ptr+VLQLEN-1) > length(smf))
info = cell(0,0);
midi = cell(0,0);
ext = cell(0,0);
disp('Midi file format error on line 224 of midird3');
fclose(fid);
return;
end
[delta,offs] = readvarlenintern(smf(ptr:ptr+VLQLEN-1));
if(delta == 0 & offs == 0)
info = cell(0,0);
midi = cell(0,0);
ext = cell(0,0);
disp('Midi file format error on line 234 of midird3');
fclose(fid);
return;
end
abstime = abstime + delta;
ptr = ptr+offs;
eventstring = sprintf('%d\t\t\t\t',delta);
next = double(uint8(smf(ptr)));
if(bitand(next,128)) % status byte found if expn TRUE
% evaluate new command (->running status)
status = next;
if TXT
eventstring = [eventstring sprintf('Status %x ',next)];
end
channel = bitand(next,15);
switch bitand(next,240) % &F0
case 144, % $90, NOTEON
runningstatus.cmd = NOTEON;
runningstatus.channel = channel;
ptr = ptr + 1;
case 128 % $80, NOTEOFF
runningstatus.cmd = NOTEOFF;
runningstatus.channel = channel;
ptr = ptr + 1;
case 160, % $A0, POLYAT
runningstatus.cmd = POLYAT;
runningstatus.channel = channel;
ptr = ptr + 1;
case 176, % $B0, CONTROLCHANGE
runningstatus.cmd = CONTROLCHANGE;
runningstatus.channel = channel;
ptr = ptr + 1;
case 192, % $C0, PROGCHANGE
runningstatus.cmd = PROGCHANGE;
runningstatus.channel = channel;
ptr = ptr + 1;
case 208, % $D0, CHANNELAT
runningstatus.cmd = CHANNELAT;
runningstatus.channel = channel;
ptr = ptr + 1;
case 224, % $E0, PITCHWHEEL
runningstatus.cmd = PITCHWHEEL;
runningstatus.channel = channel;
ptr = ptr + 1;
case 240, % $F0, EXCEPT
runningstatus.cmd = EXCEPT;
end % switch
end % if
% according to the MIDI-BNF there may be real-time events
% before each of the data bytes: we have overread them
statusnibble = bitand(double(uint8(next)),240)/16;
if statusnibble<=14
data = [];
offset = 0;
if (statusnibble == 12) | (statusnibble == 13)
bytes = 1;
else
bytes = 2;
end
%[data,offset,eventstring] = GetDataBytes(bytes,ptr,eventstring,k);
%%%%%%%%%%%%%%%%%%%%%%%
data = zeros(1,2); offset = 0;
found = 0;
while found < bytes
if(double(uint8(smf(ptr+offset)))<248)
data(found+1) = double(uint8(smf(ptr+offset)));
found = found + 1;
else
eventstring = [eventstring sprintf('Sys Realtime: %x ',double(uint8(smf(ptr+offset))))];
ext(extptr).track = k;
ext(extptr).abstime = abstime;
ext(extptr).midistring = smf(ptr+offset);
extptr = extptr + 1;
end
offset = offset + 1;
end
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
ptr = ptr + offset;
end
flag = 0;
if (runningstatus.cmd == NOTEON) & (data(2)==0)
runningstatus.cmd = NOTEOFF;
flag = 1;
end
switch runningstatus.cmd
case NOTEON,
idx12 = max(find(actnotes(:,3)==data(1)& actnotes(:,6)==runningstatus.channel));
% note number
if ~isempty(idx12)
idx = find(actnotes(idx12,4)==notes(:,4)); % compare temporary unique ID
notes(idx,4) = abstime-notes(idx,2); % new abstime
[sx,sy] = size(actnotes);
if(idx12 == sx)
actnotes = [actnotes(1:idx12-1,:)];
else
actnotes = [actnotes(1:idx12-1,:); actnotes(idx12+1:sx,:)];
end
end
if notepos == 1
Delta = abstime;
else
Delta = abstime - notes(notepos-1,2);
end
actnotes = [actnotes; Delta abstime data(1) uniqueID data(2) ...
runningstatus.channel];
notes(notepos,:) = [Delta abstime data(1) uniqueID data(2) ...
runningstatus.channel];
notepos = notepos + 1;
uniqueID = uniqueID - 1;
if TXT
eventstring = [eventstring sprintf('NOTE ON, Channel %d, Note # %d, Velocity %d ', ...
[runningstatus.channel data(1) data(2)])];
end
case NOTEOFF,
idx12 = max(find(actnotes(:,3)==data(1)& actnotes(:,6)==runningstatus.channel));
posn = max(1,notepos-7);
if ~isempty(idx12)
idx = find(actnotes(idx12,4)==notes(posn:notepos,4))...
+ posn-1; % compare temporary unique ID
if isempty(idx)
idx = find(actnotes(idx12,4)==notes(1:posn,4));
end
notes(idx,4) = abstime-notes(idx,2); % new abstime
[sx,sy] = size(actnotes);
if(idx12 == sx)
actnotes = [actnotes(1:idx12-1,:)];
else
actnotes = [actnotes(1:idx12-1,:); actnotes(idx12+1:sx,:)];
end
end
if TXT
eventstring = [eventstring sprintf('NOTE OFF, Channel %d, Note # %d, Velocity %d ', ...
[runningstatus.channel data(1) data(2)])];
end
if flag == 1
flag = 0;
runningstatus.cmd = NOTEON;
end
case POLYAT,
eventstring = [eventstring sprintf('POLYPHONIC AFTERTOUCH, Channel %d, Note # %d, AT-Pressure %d ', ...
[runningstatus.channel data(1) data(2)])];
ext(extptr).track = k;
ext(extptr).abstime = abstime;
ext(extptr).midistring = [status data(1) data(2)];
extptr = extptr + 1;
case CONTROLCHANGE,
eventstring = [eventstring sprintf('CONTROL CHANGE, Channel %d, Controller %d, Value %d ', ...
[runningstatus.channel data(1) data(2)])];
ext(extptr).track = k;
ext(extptr).abstime = abstime;
ext(extptr).midistring = [status data(1) data(2)];
extptr = extptr + 1;
switch(data(1))
case 7,
eventstring = [eventstring sprintf('(Main Volume) ')];
case 39,
eventstring = [eventstring sprintf('(Main Volume) ')];
end
if((data(1)>=hex2dec('7B')) & (data(1)<=hex2dec('7F'))) % this implies/includes ALL NOTES OFF
[lx,ly] = size(actnotes);
for kk=2:lx
idx = find(actnotes(kk,4)==notes(:,4)); % compare temporary
notes(idx,4) = abstime-notes(idx,2); % new abstime % uniqueID
end
actnotes = ones(1,TUPLEN)*-1;
end
case PROGCHANGE,
eventstring = [eventstring sprintf('PROGRAM CHANGE, Channel %d, Program # %d ', ...
[runningstatus.channel data(1)])];
ext(extptr).track = k;
ext(extptr).abstime = abstime;
ext(extptr).midistring = [status data(1)];
extptr = extptr + 1;
case CHANNELAT,
eventstring = [eventstring sprintf('CHANNEL AFTERTOUCH, Channel %d, AT-Pressure # %d ', ...
[runningstatus.channel data(1)])];
ext(extptr).track = k;
ext(extptr).abstime = abstime;
ext(extptr).midistring = [status data(1)];
extptr = extptr + 1;
case PITCHWHEEL,
eventstring = [eventstring sprintf('PITCH WHEEL CHANGE, Channel %d, MSB: %d, LSB: %d ', ...
[runningstatus.channel data(1) data(2)])];
ext(extptr).track = k;
ext(extptr).abstime = abstime;
ext(extptr).midistring = [status data(1) data(2)];
extptr = extptr + 1;
case EXCEPT,
switch(next)
case 240, % $F0, SysExclusive
[len,offs] = readvarlenintern(smf(ptr+1:ptr+VLQLEN));
eventstring = [eventstring sprintf('SysEx %x, Length %d ', ...
[next len])];
ext(extptr).track = k;
ext(extptr).abstime = abstime;
ext(extptr).midistring = smf(ptr:ptr+offs+len);
extptr = extptr + 1;
ptr = ptr + 1 + offs + len;
case 255, % $FF Meta event
metacmd = double(uint8(smf(ptr+1)));
[len,offs] = readvarlenintern(smf(ptr+2:ptr+VLQLEN+1));
eventstring = [eventstring sprintf('Meta %x ', ...
[next])];
ext(extptr).track = k;
ext(extptr).abstime = abstime;
ext(extptr).midistring = smf(ptr:ptr+offs+len+1);
extptr = extptr + 1;
if ((smf(ptr+1)>0) & (smf(ptr+1)<8))
eventstring = [eventstring smf(ptr+2+offs:ptr+1+offs+len)];
end
switch(smf(ptr+1))
case 0,
eventstring = [eventstring sprintf('Sequence %d ',Read16(smf(ptr+3:ptr+4)))];
case 47 % hex2dec('2F'),
eventstring = [eventstring sprintf('End of Track')];
[lx,ly] = size(actnotes);
for kk=2:lx
idx = find(actnotes(kk,4)==notes(:,4)); % compare temporary
notes(idx,4) = abstime-notes(idx,2); % new abstime % uniqueID
end
actnotes = ones(1,TUPLEN)*-1;
case 81, % hex2dec('51'),
eventstring = [eventstring sprintf('Set Tempo %x%x%x ',...
[double(uint8(smf(ptr+3:ptr+5)))])];
case 84, % hex2dec('54'),
eventstring = [eventstring sprintf('SMPTE Offset %x %x %x %x ',...
[double(uint8(smf(ptr+3:ptr+6)))])];
case 88, % hex2dec('58'),
eventstring = [eventstring sprintf('Time Signature %x %x %x %x ',...
[double(uint8(smf(ptr+3:ptr+6)))])];
case 89, % hex2dec('59'),
eventstring = [eventstring sprintf('Key Signature sf: %d mi: %d ',[smf(ptr+3:ptr+4)])];
case 127, % hex2dec('7F'),
eventstring = [eventstring sprintf('Sequencer specific Meta, Length %d ',[len])];
end
ptr = ptr + 2 + offs + len;
case 247, % $F7, SysExclusive
[len,offs] = readvarlenintern(smf(ptr+1:ptr+VLQLEN));
eventstring = [eventstring sprintf('SysEx %x, Length %d ', ...
[next len])];
ext(extptr).track = k;
ext(extptr).abstime = abstime;
ext(extptr).midistring = smf(ptr:ptr+offs+len);
extptr = extptr + 1;
ptr = ptr + 1 + offs + len;
case 241, % $F1, System Common (undef.)
eventstring = [eventstring sprintf('System Common %x ', ...
[next])];
ptr = ptr + 3;
ext(extptr).track = k;
ext(extptr).abstime = abstime;
ext(extptr).midistring = 241;
extptr = extptr + 1;
case 242, % $F2, Song Position Pointer (SPP)
eventstring = [eventstring sprintf('Song Position Pointer %x ', ...
[next])];
ptr = ptr + 3;
ext(extptr).track = k;
ext(extptr).abstime = abstime;
ext(extptr).midistring = smf(ptr:ptr+2);
extptr = extptr + 1;
case 243, % $F3, Sys Common; Song Select (Song #)
eventstring = [eventstring sprintf('Song Select %x ', ...
[next])];
ptr = ptr + 2;
ext(extptr).track = k;
ext(extptr).abstime = abstime;
ext(extptr).midistring = smf(ptr:ptr+1);
extptr = extptr + 1;
case 244, % $F4, Sys Common - undefined
eventstring = [eventstring sprintf('System Common (undef.) %x ', ...
[next])];
ptr = ptr + 3;
ext(extptr).track = k;
ext(extptr).abstime = abstime;
ext(extptr).midistring = smf(ptr:ptr+2);
extptr = extptr + 1;
case 245, % $F5, Sys Common - undefined
eventstring = [eventstring sprintf('System Common (undef.) %x ', ...
[next])];
ptr = ptr + 3;
ext(extptr).track = k;
ext(extptr).abstime = abstime;
ext(extptr).midistring = smf(ptr:ptr+2);
extptr = extptr + 1;
case 246, % $F6, Sys Common Tune Request
eventstring = [eventstring sprintf('System Common Tune Request %x ', ...
[next])];
ptr = ptr + 1;
ext(extptr).track = k;
ext(extptr).abstime = abstime;
ext(extptr).midistring = smf(ptr);
extptr = extptr + 1;
case 248, % $F8, Sys Real Time
eventstring = [eventstring sprintf('System Real Time %x ', ...
[next])];
ptr = ptr + 1;
ext(extptr).track = k;
ext(extptr).abstime = abstime;
ext(extptr).midistring = smf(ptr);
extptr = extptr + 1;
case 249, % $F9, Sys Real Time
eventstring = [eventstring sprintf('System Real Time %x ', ...
[next])];
ptr = ptr + 1;
ext(extptr).track = k;
ext(extptr).abstime = abstime;
ext(extptr).midistring = smf(ptr);
extptr = extptr + 1;
case 250, % $FA, Sys Real Time
eventstring = [eventstring sprintf('System Real Time %x ', ...
[next])];
ptr = ptr + 1;
ext(extptr).track = k;
ext(extptr).abstime = abstime;
ext(extptr).midistring = smf(ptr);
extptr = extptr + 1;
case 251, % $FB, Sys Real Time
eventstring = [eventstring sprintf('System Real Time %x ', ...
[next])];
ptr = ptr + 1;
ext(extptr).track = k;
ext(extptr).abstime = abstime;
ext(extptr).midistring = smf(ptr);
extptr = extptr + 1;
case 252, % $FC, Sys Real Time
eventstring = [eventstring sprintf('System Real Time %x ', ...
[next])];
ptr = ptr + 1;
ext(extptr).track = k;
ext(extptr).abstime = abstime;
ext(extptr).midistring = smf(ptr);
extptr = extptr + 1;
case 253, % $FD, Sys Real Time
eventstring = [eventstring sprintf('System Real Time %x ', ...
[next])];
ptr = ptr + 1;
ext(extptr).track = k;
ext(extptr).abstime = abstime;
ext(extptr).midistring = smf(ptr);
extptr = extptr + 1;
case 254, % $FE, Sys Real Time
eventstring = [eventstring sprintf('System Real Time %x ', ...
[next])];
ptr = ptr + 1;
ext(extptr).track = k;
ext(extptr).abstime = abstime;
ext(extptr).midistring = smf(ptr);
extptr = extptr + 1;
end
otherwise,
disp('midird3: Undefined running status!');
disp('Position:');
ptr
if TXT
eventstring = [eventstring sprintf('\n')];
fprintf(fidtxt,eventstring);
fprintf(fidtxt,'Code at Errorposition: %x \n',smf(ptr:ptr + 10));
fclose(fidtxt);
end
fclose(fid);
return;
end % switch running status
if TXT
eventstring = [eventstring sprintf('\n')];
fprintf(fidtxt,eventstring);
end
end % End: track loop
midi{k} = notes(1:notepos-1,:);
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% end: process track
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
ptr = ptrackstart + 8 + tracklen; % fwd to next track/chunk
end
if TXT
fclose(fidtxt);
end
fclose(fid);
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% extract tick resolution
%
% ms_per_tick milliseconds per tick
% ticks_per_quarter ticks per quarter note
% ms_per_quarter milliseconds per quarter note
%
% Determines the time per tick from the binary MIDI-data in ext.
% Additional functionality by Hinnerk Feldwisch and Meinard M黮ler
% added to midird3 by Frank Kurth, 11.05.2004
%
%>>>BEGIN>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
ticks_per_quarter = info.division.main;
exe = [];
for I=1:length(ext)
ex=ext(I);
if(max(abs(ex.midistring(1:2)-[255 81]))==0)
exe = ex.midistring(4:end);
end
end
if(length(exe) == 3)
microsec_per_quarter = (exe(1) * 256 + exe(2)) * 256 + exe(3);
else
microsec_per_quarter = 0; % return zero, if no time-coding was found
end
ms_per_quarter = microsec_per_quarter/1000; % == 0, if no time-coding was found !
ms_per_tick = ms_per_quarter/ticks_per_quarter; % == 0, if no time-coding was found !
%<<<END<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%
% End of main program
%
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%
% At the moment, we know Chunks with the IDs 'MThd' and 'MTrk'
% The following function sets the pointer to the starting index within smf
% (it is assumed that the MIDI file is a contiguous sequence of chunks)
%
function p = NextValidHeader(pt)
global smf;
s = char(smf(pt:pt+3));
%s = sprintf('%s',smf(pt:pt+3));
% DDD
%disp(s);
% DDD
while(~strcmp(s,'MThd') & ~strcmp(s,'MTrk'))
if(pt < 1 | (pt+3) > length(smf))
p = -1;
return;
end
len = Read32(smf(pt:pt+3));
pt = pt + 4 + 4 +len; % HeaderId + 32BitLength + Length
if pt > length(smf)
p = -1;
return
end
end
p = pt;
return;
%
% Read 4 Byte Word
%
function val = Read32(stream)
val = double(uint8(stream(1)));
for k = 2:4
val = val*256 + double(uint8(stream(k)));
end
return;
%
% Read 2 Byte Word
%
function val = Read16(stream)
val = double(uint8(stream(1)))*256 + double(uint8(stream(2)));
return;
%
% overread real time messages
%
function [dat,offs,evstring] = GetDataBytes(byte,pt,evstring)
global smf;
global abstime;
dat = zeros(1,2);
offs = 0;
found = 0;
while found < byte
if(double(uint8(smf(pt+offs)))<248)
dat(found+1) = double(uint8(smf(pt+offs)));
found = found + 1;
else
evstring = [evstring sprintf('Sys Realtime: %x ',double(uint8(smf(pt+offs))))];
end
offs = offs + 1;
end
return;
%
% readvarleninternIntern
%
function [value,len] = readvarlenintern(stream)
% function [value,len] = readvarlenintern(stream) read MIDI variable length quantity number
%
% 'value' returns the resulting Number, len is the number of values read from the
% input smf-stream 'stream'
%
len = 1;
value = 0;
if(len > length(stream))
value = 0;
len = 0;
return;
end
act = double(uint8(stream(len)));
value = act;
if(bitand(act,128))
value = bitand(act,127);
while bitand(act,128)
len = len + 1;
if(len > length(stream))
value = 0;
len = 0;
return;
end
act = double(uint8(stream(len)));
value = value * 128 + bitand(act,127);
end
end