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Drop of 0.87 release.

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Ross Duggan
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========================
MIDIUtil Class Reference
========================
--------------
class MIDIFile
--------------
A class that represents a full, well-formed MIDI pattern.
This is a container object that contains a header, one or more
tracks, and the data associated with a proper and well-formed
MIDI pattern.
Calling
MyMIDI = MidiFile(tracks, removeDuplicates=True,  deinterleave=True)
normally
MyMIDI = MidiFile(tracks)
Arguments
o tracks: The number of tracks this object contains
o removeDuplicates: If true (the default), the software will
remove duplicate events which have been added. For example,
two notes at the same channel, time, pitch, and duration would
be considered duplicate.
o deinterleave: If True (the default), overlapping notes
(same pitch, same channel) will be modified so that they do
not overlap. Otherwise the sequencing software will need to
figure out how to interpret NoteOff events upon playback.
================
Public Functions
================
---------------------------------------------------
addNote(track, channel, pitch,time,duration,volume)
---------------------------------------------------
Add notes to the MIDIFile object
Use
MyMIDI.addNotes(track,channel,pitch,time, duration, volume)
Arguments
o track: The track to which the note is added.
o channel: the MIDI channel to assign to the note. [Integer, 0-15]
o pitch: the MIDI pitch number [Integer, 0-127].
o time: the time (in beats) at which the note sounds [Float].
o duration: the duration of the note (in beats) [Float].
o lume: the volume (velocity) of the note. [Integer, 0-127].
----------------------------------
addTrackName(track, time,trackName)
----------------------------------
Add a track name to a MIDI track.
Use
MyMIDI.addTrackName(track,time,trackName)
Arguments
o track: The track to which the name is added. [Integer, 0-127].
o time: The time at which the track name is added, in beats
[Float].
o trackName: The track name. [String].
---------------------------
addTempo(track, time,tempo)
---------------------------
Add a tempo event.
Use
MyMIDI.addTempo(track, time, tempo)
Arguments
o track: The track to which the event is added. [Integer, 0-127]
o time: The time at which the event is added, in beats. [Float]
o tempo: The tempo, in Beats per Minute. [Integer]
-----------------------------------------------
addProgramChange(track, channel, time, program)
-----------------------------------------------
Add a MIDI program change event.
Use
MyMIDI.addProgramChange(track,channel, time, program)
Arguments
o track: The track to which the event is added. [Integer, 0-127]
o channel: The channel the event is assigned to. [Integer, 0-15]
o time: The time at which the event is added, in beats. [Float]
o program: the program number. [Integer, 0-127]
--------------------------------------------------------------
addControllerEvent(track, channel,time,eventType, paramerter1)
--------------------------------------------------------------
Add a MIDI controller event.
Use
MyMIDI.addControllerEvent(track, channel, time, eventType, \
parameter1)
Arguments
o track: The track to which the event is added. [Integer, 0-127]
o channel: The channel the event is assigned to. [Integer, 0-15]
o time: The time at which the event is added, in beats. [Float]
o eventType: the controller event type.
o parameter1: The event's parameter. The meaning of which varies
by event type.
---------------------------------------------------------------------
changeNoteTuning(track, tunings, sysExChannel=0x7F, realTime=False, \
tuningProgam=0)
---------------------------------------------------------------------
Change a note's tuning using sysEx change tuning program.
Use
MyMIDI.changeNoteTuning(track,[tunings],realTime=False, \
tuningProgram=0)
Arguments
o track: The track to which the event is added. [Integer, 0-127].
o tunings: A list of tuples in the form (pitchNumber,
frequency).  [[(Integer,Float]]
o realTime: Boolean which sets the real-time flag. Defaults to false.
o sysExChannel: do note use (see below).
o tuningProgram: Tuning program to assign. Defaults to
zero. [Integer, 0-127]
In general the sysExChannel should not be changed (parameter will
be depreciated).
Also note that many software packages and hardware packages do not
implement this standard!
---------------------
writeFile(fileHandle)
---------------------
Write the MIDI File.
Use
MyMIDI.writeFile(filehandle)
Arguments
o filehandle: a file handle that has been opened for binary
writing.
-------------------------------------
addSysEx(track, time, manID, payload)
-------------------------------------
Add a SysEx event
Use
MyMIDI.addSysEx(track,time,ID,payload)
Arguments
o track: The track to which the event is added. [Integer, 0-127].
o time: The time at which the event is added, in beats. [Float].
o ID: The SysEx ID number
o payload: the event payload.
Note: This is a low-level MIDI function, so care must be used in
constructing the payload. It is recommended that higher-level helper
functions be written to wrap this function and construct the payload
if a developer finds him or herself using the function heavily.
---------------------------------------------------------
addUniversalSysEx(track,  time,code, subcode, payload, \
sysExChannel=0x7F,  realTime=False)}f
---------------------------------------------------------
Add a Universal SysEx event.
Use
MyMIDI.addUniversalSysEx(track, time, code, subcode, payload, \
sysExChannel=0x7f, realTime=False)
Arguments
o track: The track to which the event is added. [Integer, 0-127].
o time: The time at which the event is added, in beats. [Float].
o code: The event code. [Integer]
o subcode The event sub-code [Integer]
o payload: The event payload. [Binary string]
o sysExChannel: The SysEx channel.
o realTime: Sets the real-time flag. Defaults to zero.
Note: This is a low-level MIDI function, so care must be used in
constructing the payload. It is recommended that higher-level helper
functions be written to wrap this function and construct the payload
if a developer finds him or herself using the function heavily. As an
example of such a helper function, see the changeNoteTuning function,
both here and in MIDITrack.

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=====================
Extending the Library
=====================
The choice of MIDI event types included in the library is somewhat
idiosyncratic; I included the events I needed for another software
project I was wrote. You may find that you need additional events in
your work. For this reason I am including some instructions on extending
the library. The process isn't too hard (provided you have a working
knowledge of Python and the MIDI standard), so the task shouldn't present
a competent coder too much difficulty. Alternately (if, for example,
you *don't* have a working knowledge of MIDI and don't desire to gain it),
you can submit new feature requests to me, and I will include them into
the development branch of the code, subject to the constraints of time.
To illustrate the process I show below how the MIDI tempo event is
incorporated into the code. This is a relatively simple event, so while
it may not illustrate some of the subtleties of MIDI programing, it
provides a good, illustrative case.
-----------------------
Create a New Event Type
-----------------------
The first order of business is to create a new subclass of the GnericEvent
object of the MIDIFile module. This subclass initializes any specific
instance data that is needed for the MIDI event to be written. In
the case of the tempo event, it is the actual tempo (which is defined
in the MIDI standard to be 60000000 divided by the tempo in beats per
minute). This class should also call the superclass' initializer with
the event time and set the event type (a unique string used internally by
the software) in the __init__() function. In the case of the tempo event:
class tempo(GenericEvent):
def __init__(self,time,tempo):
GenericEvent.__init__(self,time)
self.type = 'tempo'
self.tempo = int(60000000 / tempo)
Next (and this is an embarrassing break of OO programming) the __eq__()
function of the GenericEvent class should be modified so that equality
of these types of events can be calculated. In calculating equivalence
time is always checked, so two tempo events are considered the same if
the have the same tempo value. Thus the following snippet of code from
GenericEvent's _eq__() function accomplishes this goal:
if self.type == 'tempo':
if self.tempo != other.tempo:
return False
If events are equivalent, the code should return False. If they are not
equivalent no return should be called.
---------------------------
Create an Accessor Function
---------------------------
Next, an accessor function should be added to MIDITrack to create an
event of this type. Continuing the example of the tempo event:
def addTempo(self,time,tempo):
self.eventList.append(MIDITrack.tempo(time,tempo))
The public accessor function is via the MIDIFile object, and must include
the track number to which the event is written:
def addTempo(self,track,time,tempo):
self.tracks[track].addTempo(time,tempo)
This is the function you will use in your code to create an event of
the desired type.
-----------------------
Modify processEventList
-----------------------
Next, the logic pertaining to the new event type should be added to
processEventList function of the MIDITrack class. In general this code
will create a MIDIEvent object and set its type, time, ordinality, and
any specific information that is needed for the event type. This object
is then added to the MIDIEventList.
The ordinality (self.ord) is a number that tells the software how to
sequence MIDI events that occur at the same time. The higher the number,
the later in the sequence the event will be written in comparison to
other, simultaneous events.
The relevant section for the tempo event is:
elif thing.type == 'tempo':
event = MIDIEvent()
event.type = "Tempo"
event.time = thing.time * TICKSPERBEAT
event.tempo = thing.tempo
event.ord = 3
self.MIDIEventList.append(event)
Thus if other events occur at the same time, type which have an ordinality
of 1 or 2 will be written to the stream first.
Time needs to be converted from beats (which the accessor function uses)
and MIDI time by multiplying by the constant TICKSPERBEAT. The value
of thing.type is the unique string you defined above, and event.type
is another unique things (they can--and probably should--be the same,
although the coding here is a little sloppy and changes case of the
string).
----------------------------------------
Write the Event Data to the MIDI Stream
----------------------------------------
The last step is to modify the MIDIFile writeEventsToStream function;
here is where some understanding of the MIDI standard is necessary. The
following code shows the creation of a MIDI tempo event:
elif event.type == "Tempo":
code = 0xFF
subcode = 0x51
fourbite = struct.pack('>L', event.tempo)
threebite = fourbite[1:4] # Just discard the MSB
varTime = writeVarLength(event.time)
for timeByte in varTime:
self.MIDIdata = self.MIDIdata + struct.pack('>B',timeByte)
self.MIDIdata = self.MIDIdata + struct.pack('>B',code)
self.MIDIdata = self.MIDIdata + struct.pack('>B',subcode)
self.MIDIdata = self.MIDIdata + struct.pack('>B', 0x03)
self.MIDIdata = self.MIDIdata + threebite
The event.type string ("Tempo") was the one chosen in the processEventList
logic.
The code and subcode are binary values that come from the MIDI
specification.
Next the data is packed into a three byte structure (or a four byte
structure, discarding the most significant byte). Again, the MIDI
specification determines the number of bytes used in the data payload.
The event time should be converted to MIDI variable-length data with the
writeVarLength() function before writing to the stream (as shown above).
The MIDI standard utilizes a slightly bizarre variable length data
record. In it, only seven bits of a word are used to store data; the
eighth bit signifies if more bytes encoding the value follow. The total
length may be 1 to 3 bytes, depending upon the size of the value encoded.
The writeVarLength() function takes care of this conversion for you.
Now the data is written to the binary object self.MIDIdata, which is
the actual MIDI-encoded data stream. As per the MIDI standard, first we
write our variable-length time value. Next we add the event type code and
subcode. Then we write the length of the data payload, which in the case
of the tempo event is three bytes. Lastly, we write the actual payload,
which has been packed into the variable threebite.
Clear as mud!