SMPTE.py

#! /usr/bin/env python
# -*- coding: utf-8 -*-

# Converts frames to SMPTE timecode of arbitrary frame rate and back.
# Copyright 2018, Igor Riđanović, Igor@hdhead.com, Meta Fide
# adapted by mivk, 2020

class SMPTE(object):
	'''Frames to SMPTE timecode converter and reverse.'''

	def __init__(self, *args):
		self.fps = args[0] if len(args) > 0 else 24
		self.df  = args[1] if len(args) > 1 else False

	def df_check(self):
		if self.df and ( self.fps == int(self.fps) or int(self.fps) not in (29, 59) ):
			import sys
			sys.stderr.write('Ignoring invalid drop-frame option with ' + str(self.fps) + " fps!\n")
			return False

	def getframes(self, tc):
		'''Converts SMPTE timecode to frame count.'''

		# Always round fractional frame rate.
		self.fps = int(round(self.fps))

		# Validate timecode
		if len(tc) != 11:
			raise ValueError ('Malformed SMPTE timecode', tc)
		if int(tc[9:]) >= self.fps:
			raise ValueError ('SMPTE timecode to frame rate mismatch.', tc, self.fps)

		# Calculate timecode to frames for fps time base
		min = int(tc[:2])*60 + int(tc[3:5])
		sec = int(tc[6:8])
		frm =	int((min*60 + sec) * self.fps + int(tc[9:]))

		# Drop frame adjustment
		if self.df and self.df_check():
			# Subtract 2 frames for each minute...
			dffrm =  frm - min * 2
			# ...except every 10 minutes.
			tens = min / 10
			dffrm += tens * 2
			return dffrm

		return frm


	def gettc(self, frames):
		'''Converts frame count to SMPTE timecode.'''

		# Always round fractional frame rate.
		self.fps = int(round(self.fps))

		frames = abs(frames)
		spacer = spacer2 = ':'

		# Drop frame adjustment
		if self.df and self.df_check():
			spacer2 = ';'
			minfactor    = self.fps * 60
			tenminfactor = self.fps * 600

			# Add 2 frames for each minute...
			frames += frames/minfactor * 2
			# ...except every ten minutes
			frames -= frames/tenminfactor * 2

		frHour = self.fps * 3600
		frSec = self.fps * 60
		hr = int(frames // frHour)
		mn = int((frames - hr * frHour) // frSec)
		sc = int((frames - hr * frHour - mn * frSec) // self.fps)
		fr = int(round(frames -  hr * frHour - mn * frSec - sc * self.fps))

		return(
				str(hr).zfill(2) + spacer +
				str(mn).zfill(2) + spacer +
				str(sc).zfill(2) + spacer2 +
				str(fr).zfill(2))