#!/usr/bin/python

# Python script to tranlate black frame listing produced by mencoder with 
# "-vf blackframe" into a list of times suitable for use as a chapter list
# with dvdauthor.

# Feel free to redistribute, modify, or do whatever you want to do with this 
# file.  I don't care.

import sys

framerate = 25.0
threshold_length = 10
data = "0"
lasttime = ["00", "00", "00"]

def secs_diff (time1, time2):
	return (int(time2[2]) - int(time1[2])) + 60*(int(time2[1]) - int(time1[1])) + 3600*(int(time2[0]) - int(time1[0]))

def time_from_frame (frameno):
	seconds = frameno / framerate
	intsec = int(seconds)
	thou = int((seconds - intsec) * 1000)
	hours = intsec / 3600
	minutes = (intsec / 60) % 60
	seconds = intsec % 60
	return "%02d:%02d:%02d.%03d" % (hours, minutes, seconds, thou)

groupstart = -2
grouplen = 0

if len(sys.argv) > 1:
	framerate = float(sys.argv[1])
if len(sys.argv) > 2:
	threshold_length = int(sys.argv[2])

for line in sys.stdin:
	if line[0:12] != "Black frame:":
		continue

	splitln = line.strip().split (' ')
	if len(splitln) < 5:
		print "malformed line: " + line
		continue

	frameno = int(splitln[3])
	#print frameno,groupstart,grouplen
	if frameno != groupstart + grouplen + 1:
		if grouplen > threshold_length:
			time = time_from_frame (groupstart + grouplen/2)
			th = time.split('.')

			timea = th[0].split (':')
			if secs_diff (lasttime, timea) < 30:
				print "skipping " + time + " (delta t = " + repr(secs_diff (lasttime, timea)) + ")"
			else:
				print "group from " + str(groupstart) + " (" + time_from_frame(groupstart) + ") to " + str(groupstart+grouplen) + " (" + time_from_frame(groupstart+grouplen) + ")"
				if time.startswith("00:"):
					time = time[3:]

				data += ", " + time
				lasttime = timea
		groupstart = frameno
		grouplen = 0
	else:
		grouplen = grouplen + 1
print data