rtmidi/simplemidi/midiparser.py

#!/usr/bin/python

from .midimessage import *

class MIDITrack:
	def __init__(self):
		pass

class InputStreamWrapper:
	def __init__(self, fd, mode="rb"):
		if isinstance(fd, str):
			fd=open(fd, mode)
		self.fd=fd
		self.buffer=[]
		self.n=0
		self.offset=0
		self.doRecord=False
		
	def close(self):
		self.fd.close()

	
	def read(self, n=-1):
		x=self.fd.read(n)
		self.offset+=n
		if self.doRecord: self.buffer+=x
		return x
	
	def record(self, rec=True):
		self.doRecord=rec

		

class MIDIChunk:
	def __init__(self, fd):
		self.fd=fd
		self.magick=""
		self.length=0
	
	def parse(self):
		pass
	
	def print(self):
		pass
	
	def readMagick(self):
		return self.fd.read(4).decode('ascii')
	
	def reverseMsb(self, x):
		out=0
		n=len(x)
		for i in reversed(range(n)):
			out+= (x[i]<< (8*(n-1-i)))
		return out
	
	def intN(self, n):
		return self.reverseMsb(self.fd.read(n))
	
	def int4(self):
		return self.intN(4)
		
	def int2(self):
		return self.intN(2)
		
	def byte(self):
		return self.intN(1)
		
	def skip(self, n=1):
		self.fd.read(n)

class MIDIHeaderChunk(MIDIChunk):
	def __init__(self, fd):
		MIDIChunk.__init__(self,fd)
		self.format=0
		self.tracks=0
		self.division=0
		MIDIHeaderChunk.FORMAT_SINGLE_CHANNEL=0
		MIDIHeaderChunk.FORMAT_MULTIPLE_CHANNEL=1
		MIDIHeaderChunk.FORMAT_MULTIPLE_INDEPENDANT_CHANNEL=2
		
		self.variableTicks=False
		self.ticksPerQuarter=0 # beat per quarter note
	
	def parse(self):
		f=self.fd
		self.magick=self.readMagick()
		if self.magick!="MThd":
			raise MIDIParserException("Bad header magick number")

		self.length=self.int4()
		self.format=self.int2()
		self.tracks=self.int2()
		self.division=self.int2()
		
		self.variableTicks=True if self.division & 0x8000 else False
		if not self.variableTicks:
			self.ticksPerQuarter= self.division & 0x7fff

class MIDITrackChunk(MIDIChunk):
	def __init__(self, fd, skipTrack=False):
		MIDIChunk.__init__(self,fd)
		self.time=0
		self.events=[]
		self.skipTrack=skipTrack
	
	def readDeltaTime(self):
		out=[]
		while True:
			x=self.byte()
			out.append(x&0x7F)
			if not (x&0x80):
				break
		n=len(out)
		ret=0
		for i in range(n):
			j=n-i-1
			ret+= ( (out[i]) <<(j*7) )
			
		self.time+=ret
		return ret
	
	def parse(self):
		f=self.fd
		self.magick=self.readMagick()
		if self.magick!="MTrk":
			raise MIDIParserException("Bad track magick number")
		self.length=self.int4()
		
		events=[]
		if self.skipTrack: self.fd.read(self.length)
		else:
			while True:
				delta=self.readDeltaTime()
				evt=self.readEvent()

				
				events.append((self.time, evt))
				if evt.isEndTrack():
					break
		return events
	

			
	def readEvent(self):
		return MidiMessage.parse(self.fd)
		
class MidiFile:
	def __init__(self, path):
		self.path=path
		self.tracksCount=0
		self.header=None
		self.tracks=[]
		self.loaded=False
	
	def parse(self):
		self.fd=0
		try:
			self.fd=open(self.path, "rb")
		except Exception as e:
			ERR(type(e).__name__+" : "+str(e))
			return e
		self.header=MIDIHeaderChunk(self.fd)
		self.header.parse()
		for t in range(self.header.tracks):
			track=MIDITrackChunk(self.fd)
			
			self.tracks.append(track.parse())
		self.fd.close()
		self.loaded=True
		
	def isLoaded(self):
		return self.loaded
		

if __name__=="__main__":	
	#path="/home/fanch/Documents/tabs/Johann Pachelbel - Canon In D (ver 6 by Ezechiel).mid"
	path="/home/fanch/Documents/tabs/Misc Traditional - Katyusha.mid"
	m=MidiFile(path)
	m.parse()