Timing of MIDI events in seconds

midi_timings.py

#!/usr/bin/env python2.7

import sys
import midi

def getTempoMap(pattern, maxTick=None):
    #create a first tempo (default to 120, if there is no tempo event)
    tempoMap = [[0, .5 / pattern.resolution]]
    lastTick = 0
    for track in pattern:
        for event in track:
            if maxTick is not None and event.tick > maxTick:
                continue
            if isinstance(event, midi.SetTempoEvent):
                #set the first tempo event if tick=0
                if not event.tick:
                    tempoMap[0][1] = 60. / pattern.resolution / event.bpm
                #set duration of the previous tempo event
                else:
                    tempoMap[-1][0] = event.tick
                    tempoMap.append([0, 60. / pattern.resolution / event.bpm])
        lastTick = max(lastTick, event.tick)

    #set duration of last tempo change based on latest event tick
    tempoMap[-1][0] = lastTick
    return list(sorted(tempoMap, key=lambda e: e[0]))


#return timing of a single event, from a given the pattern,
#using the track and event number
def getEventTime(pattern, trackId, eventId):
    relative = pattern.tick_relative
    pattern.make_ticks_abs()
    maxTick = pattern[trackId][eventId].tick
    tempoMap = getTempoMap(pattern, maxTick)
    pattern.make_ticks_rel()

    tick = time = 0
    tempoMap = iter(tempoMap)
    nextTick, tickLength = tempoMap.next()

    while nextTick < maxTick:
        time += (nextTick - tick) * tickLength
        tick = nextTick
        nextTick, tickLength = tempoMap.next()

    #restore previous status
    if not relative:
        pattern.make_ticks_abs()
    #add remaining ticks
    return time + (maxTick - tick) * tickLength


#with a given pattern and track number, return a list of (event, time)
def getTrackTimings(pattern, trackId, noteOff=False):
    relative = pattern.tick_relative
    pattern.make_ticks_abs()
    tempoMap = getTempoMap(pattern)
    pattern.make_ticks_rel()

    eventType = midi.NoteEvent if noteOff else midi.NoteOnEvent

    tick = time = 0
    tempoMap = iter(tempoMap)
    nextTick, tickLength = tempoMap.next()

    notes = []
    iterEvents = iter(pattern[trackId])
    event = iterEvents.next()
    while True:
        try:
            while tick + event.tick < nextTick:
                time += event.tick * tickLength
                tick += event.tick
                if isinstance(event, eventType):
                    notes.append((event, time))
                event = iterEvents.next()
            remaining = nextTick - tick
            time += remaining * tickLength
            tick += remaining

            nextTick, tickLength = tempoMap.next()

            #check for other tempo changes
            while tick + (event.tick - remaining) > nextTick:
                remaining = nextTick - tick
                time += remaining * tickLength
                tick += remaining
                nextTick, tickLength = tempoMap.next()

            time += (event.tick - remaining) * tickLength
            tick += (event.tick - remaining)

            if isinstance(event, eventType):
                notes.append((event, time))

            event = iterEvents.next()

        except StopIteration:
            if not relative:
                pattern.make_ticks_abs()
            return notes

getNote = lambda n: ['C', 'C#', 'D', 'D#', 'E', 'F', 'F#', 'G', 'G#', 'A', 'A#', 'B'][n % 12] + str(n // 12 - 2)

pattern = midi.read_midifile(sys.argv[1])
timings = getTrackTimings(pattern, 1)
for event, time in timings:
    print('Note {} plays at {:.02f} seconds'.format(getNote(event.pitch), time))