Given MIDICSV output, convert MIDI timebase to a target timebase

midicsv_convert_timebases.py

#!/usr/bin/python

import csv
import sys

if len(sys.argv) < 2:
	print("midicsv_convert_timebases.py [to_timebase]")
	print()
	print("e.g. midicsv MYMIDI.mid | midicsv_convert_timebases.py 96 | csvmidi - > MYMIDI_corrected.mid")
	exit(0)

to_timebase = int(sys.argv[1].strip())

# CSV entry list.
command_bin = []

with sys.stdin as csvfile:
	reader = csv.reader(csvfile, delimiter=',')
	old_tick = -1
	
	from_timebase = -1
	
	for row in reader:
		track = int(row[0])
		tick = int(row[1])
		event = row[2].lower().strip()
		data = [x.strip() for x in row[3:]]
		
		if event == "header":
			from_timebase = int(data[2])
			data[2] = str(to_timebase)
		
		if from_timebase > 0:
			tick = round(tick/from_timebase*to_timebase)

		csv_string = "%d, %d, %s, %s" % (
			track, tick, event, ', '.join(data)
		)
		command_bin.append(csv_string)

sys.stdout.write(
	'\n'.join(command_bin)
)