cue2cu2.py

#!/usr/bin/env python3

# cue2cu2 - converts a cue sheet to CU2 format.
# Originally written by NRGDEAD in 2019. Use at your own risk.
# This program was written based on my web research and my reverse engineering of the CU2 format.
# Sorry, this is my first Python thingie. I have no idea what I'm doing. Thanks.
# WWW: https://github.com/NRGDEAD/Cue2cu2

# Copyright 2019-2020 NRGDEAD
# 
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
# 
#     http://www.apache.org/licenses/LICENSE-2.0
# 
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.

# Import functions or something?
import argparse
import os
import sys
import re

# Function to convert timecode/index position to sector count
def convert_timecode_to_sectors(timecode):
	minutes = int(timecode[0:2])
	seconds = int(timecode[3:5])
	sectors = int(timecode[6:8])
	minutes_sectors = int(minutes*60*75)
	seconds_sectors = int(seconds*75)
	total_sectors = int(minutes_sectors+seconds_sectors+sectors)
	return total_sectors

# Function to convert sectors to timcode
def convert_sectors_to_timecode(sectors):
	total_seconds = int(int(sectors)/75)
	modulo_sectors = int(int(sectors)%75)
	total_minutes = int(total_seconds/60)
	modulo_seconds = int(total_seconds%60)
	timecode = str(total_minutes).zfill(2)+":"+str(modulo_seconds).zfill(2)+":"+str(modulo_sectors).zfill(2)
	return timecode

# Function to convert sectors to timcode - but use MM:SS-1:75 instead of MM:SS:00. Thanks for finding that oddity, bikerspade!
def convert_sectors_to_timecode_with_alternative_notation(sectors):
	total_seconds = int(int(sectors)/75)
	modulo_sectors = int(int(sectors)%75)
	total_minutes = int(total_seconds/60)
	modulo_seconds = int(total_seconds%60)
	if modulo_sectors == 0:
		modulo_sectors = int(75)
		if modulo_seconds != 0:
			modulo_seconds = modulo_seconds - 1
		else:
			modulo_seconds = 59
			total_minutes = total_minutes - 1
	timecode = str(total_minutes).zfill(2)+":"+str(modulo_seconds).zfill(2)+":"+str(modulo_sectors).zfill(2)
	return timecode

# Function to get the total runtime timecode for a given filesize
def convert_bytes_to_sectors(filesize):
	if filesize % 2352 == 0:
		return int(int(filesize)/2352)
	else:
		error("The filesize of the binary file or --size parameter indicates that this is not a valid image in MODE2/2352")

# Function to get the total runtime timecode for a given file
def convert_filesize_to_sectors(binaryfile):
	if os.path.exists(binaryfile):
		return convert_bytes_to_sectors(os.path.getsize(binaryfile))
	else:
		error("Cue sheet refers to a binary file, "+binaryfile+", that could not be found. To manually override, use the --size parameter. See --help.")

# Function to add two timecodes together
def timecode_addition(timecode, offset):
	result = convert_timecode_to_sectors(timecode)+convert_timecode_to_sectors(offset)
	if result > int("449999"):
		result = int("449999") 
	return convert_sectors_to_timecode(result)

# Function to substract timecodes
def timecode_substraction(timecode, offset):
	result = convert_timecode_to_sectors(timecode)-convert_timecode_to_sectors(offset)
	if result < int("0"):
		result = int("0") 
	return convert_sectors_to_timecode(result)

# Function to throw an error and exit when something went wrong
def error(message):
	if message:
		print("Cue2cu2: Error while processing "+cuesheet+": "+message+".", file=sys.stderr)
		sys.exit(-1)
	else:
		print("Cue2cu2: Error while processing "+cuesheet+".", file=sys.stderr)
		sys.exit(-1)

# Function to warn about something, but continue
def warning(message):
	if args.quiet == False:
		if message:
			print("Cue2cu2: Warning while processing "+cuesheet+": "+message+".", file=sys.stderr)
		else:
			print("Cue2cu2: Undefined warning while processing "+cuesheet+".", file=sys.stderr)

# Parsing arguments with argparse
parser = argparse.ArgumentParser(description="Cue2cu2 converts a cue sheet to CU2 format")
parser.add_argument("-c","--compat", action="store_true",  help="Enables compatibility mode, aims to be bit-identical to what Systems Console would produce (default)")
parser.add_argument("-nc","--nocompat", action="store_true", help="Disables compatibility mode, produces a CU2 sheet without offset correction. Included for user experiments")
parser.add_argument("-f","--format", type=int, help="Specify CU2 format revision: 1 for Systems Console up to 2.4 (and sort of 2.5 to 2.7), 2 for 2.8 and probably later versions (default: 2)")
parser.add_argument("-s","--size", type=int, help="Manually specify binary filesize in bytes instead of obtaining it from the binary file")
parser.add_argument("-n","--name", type=str, help="Specify output filename instead of obtaining it from the cue sheet")
parser.add_argument("-o","--offset", type=str, help="Specify timecode offset for audio tracks and track end. Format: [+/-]MM:SS:ss, as in Minutes (00-99), Seconds (00-59), sectors (00-74). Example: -o=-00:13:37. Note: resulting output range is limited to 00:00:00 - 99:59:74")
parser.add_argument("-os","--offset-select", type=str, help="Select the variables the offset will be applied to instead of the default audio tracks, pregaps, and track end only. Capitalization and order is arbitrary. Variables are represented by single letters: A (audio tracks), P (pregaps), E (track end), S (size), D (data1). Example to select everything: -os PASED")
parser.add_argument("-1","--stdout", action="store_true",  help="Output to stdout instead of a CU2 file named after the binary image file")
parser.add_argument("-q","--quiet", action="store_true",  help="Suppress warning messages")
parser.add_argument("cuesheet")
args = parser.parse_args()

# Make this a little more handy
cuesheet = args.cuesheet

# Configure compatibility mode
compatibility_mode = bool(True) # Default value
if args.nocompat:
	compatibility_mode = bool(False)
if args.compat:
	compatibility_mode = bool(True)
if args.compat == args.nocompat == True:
	error("Can not enable and disable compatibility mode at the same time, d'uh")

# Configure CU2 format revision
format_revision = int(2) # Default value
if args.format or str(args.format) == "0":
	if args.format == int(1):
		format_revision = int(1)
	elif args.format == int(2):
		format_revision = int(2)
	else:
		error("CU2 format revision must be either 1 or 2. Supplied: "+str(args.format))

# Should we output to the filesystem or stdout?
if args.stdout:
	stdout = bool(True)
else:
	stdout = bool(False)

# Do we get the filesize for the binary file from the file listed in the cue sheet or from an argument?
if args.size:
	filesize = int(args.size)
else:
	filesize = bool(False)

# Do we have an output filename? If not, we'll think about one later
if args.name:
	cu2sheet = args.name
else:
	cu2sheet = bool(False)

# Do we want to apply an offset to the timecodes?
if args.offset:
	offset_supplied = bool(True)
	# Is this a valid timecode with optional sign?
	if re.compile("^[+-]{0,1}[0-9]{2}:[0-5][0-9]:[0-7][0-9]$").match(args.offset) and int(args.offset[::-1][0:2][::-1]) <= int("74"):
		# Do we add or substract the timecode?
		if args.offset[0] == str("+"):
			offset_mode_is_add = bool(True)
			offset_timecode = str(args.offset[1:9])
		elif re.compile("^[0-9]$").match(args.offset[0]):
			offset_mode_is_add = bool(True)
			offset_timecode = str(args.offset)
		elif args.offset[0] == str("-"):
			offset_mode_is_add = bool(False)
			offset_timecode = str(args.offset[1:9])
	else:
		error("Supplied offset is invalid. Format: [+/-]MM:SS:ss, as in Minutes (00-99), Seconds (00-59), sectors (00-74)")
else:
	offset_supplied = bool(False)

# "Decode" the variable selection string and throw an error if there's something unexpected in it
if args.offset_select:
	if re.compile("^[DdAaPpEeSs]{1,5}$").match(args.offset_select) and offset_supplied == True:
		# Look for individual letters and set variables accordingly
		if re.compile(".*[Dd].*").match(args.offset_select):
			offset_data1 = bool(True)
		else:
			offset_data1 = bool(False)
		if re.compile(".*[Aa].*").match(args.offset_select):
			offset_audio = bool(True)
		else:
			offset_audio = bool(False)
		if re.compile(".*[Pp].*").match(args.offset_select):
			offset_pregaps = bool(True)
			if format_revision == int(1):
				warning("An offset was to be applied to the pregaps, but format "+str(format_revision)+" does not support pregaps")

		else:
			offset_pregaps = bool(False)
		if re.compile(".*[Ee].*").match(args.offset_select):
			offset_end = bool(True)
		else:
			offset_end = bool(False)
		if re.compile(".*[Ss].*").match(args.offset_select):
			offset_size = bool(True)
		else:
			offset_size = bool(False)
	elif offset_supplied == False:
		error("Offset selection supplied but no offset")
	else:
		error("Badly formatted offset selection string. Accepted are only the letters A, E, S, and D")
else: # The default values
	offset_data1 = bool(False)
	offset_audio = bool(True)
	if format_revision == int(2):
		offset_pregaps = bool(True)
	else:
		offset_pregaps = bool(False)
	offset_end = bool(True)
	offset_size = bool(False)

# Now, onto the actual work

# Copy the cue sheet into an array so we don't have to re-read it from disk again and can navigate it easily
try:
	with open(cuesheet,"r") as cuesheet_file:
		cuesheet_content = cuesheet_file.read().splitlines()
		cuesheet_file.close
except:
	error("Could not open "+str(cuesheet))

# Check the cue sheet if the image is supposed to be in Mode 2 with 2352 bytes per sector
for line in cuesheet_content:
	cuesheet_mode_valid = bool(False)
	if re.compile(".*[Mm][Oo][Dd][Ee]2/2352.*").match(line):
		cuesheet_mode_valid = bool(True)
		break
if cuesheet_mode_valid == False: # If it's not, we can't continue
	error("Cue sheet indicates this image is not in MODE2/2352")

# Make sure this not a multi bin image, but does include exactly one FILE statement
files = int(0)
for line in cuesheet_content:
	if re.compile("[ \t]*[Ff][Ii][Ll][Ee].*").match(line):
		files += 1
if not files == int(1):
	error("The cue sheet is either invalid or part of an image with multiple binary files, which are not supported by this version of Cue2cu2")

# Extract the filename of the main image or binary file
for line in cuesheet_content:
	if re.compile("[ \t]*[Ff][Ii][Ll][Ee].*[Bb][Ii][Nn][Aa][Rr][Yy].*").match(line):
		binaryfile = str(line)[6:][::-1][8:][::-1]
		break
	else:
		error("Could not find binary file")

# Now obtain the variables to be used for the output and add them to said output

output = str()

# Get number of tracks from cue sheet
ntracks = 0
for line in cuesheet_content:
	if re.compile("[ \t]*[Tt][Rr][Aa][Cc][Kk].*").match(line) and not re.compile("[ \t]*[Ff][Ii][Ll][Ee].*[Tt][Rr][Aa][Cc][Kk].*").match(line): # Thanks for finding that bug, staticanime!
		ntracks += 1
output = output+"ntracks "+str(ntracks)+"\r\n"

# Get the total runtime/size
if not filesize == False:
	size = convert_sectors_to_timecode(convert_bytes_to_sectors(filesize))
else:
	size = convert_sectors_to_timecode(convert_filesize_to_sectors(binaryfile))
# Add the two seconds for compatibility if needed
if compatibility_mode == True and format_revision == int(1):
	size = timecode_addition(size,"00:02:00")
# Apply offset if supplied
if offset_supplied == True and offset_size == True:
	if offset_mode_is_add == True:
		size = timecode_addition(size, offset_timecode)
	elif offset_mode_is_add == False:
		size = timecode_substraction(size, offset_timecode)

output = output+"size      "+size+"\r\n"

# Get data1 - well, this is always the same for our kind of disc images, so...
# At some point I should do this the proper way and grab it from Track 1.
data1 = "00:00:00"
if compatibility_mode == True:
	data1 = timecode_addition(data1,"00:02:00")
# Apply offset if supplied
if offset_supplied == True and offset_data1 == True:
	if offset_mode_is_add == True:
		data1 = timecode_addition(data1, offset_timecode)
	elif offset_mode_is_add == False:
		data1 = timecode_substraction(data1, offset_timecode)
output = output+"data1     "+data1+"\r\n"

# Get the track and pregap lengths
pregap_command_used_before = bool(False) # In case we later find the PREGAP command, which would be bad
for track in range(2, ntracks+1): # Why do I have to +1 this? Python is weird
	# Find current track number in cuesheet_content
	current_track_in_cuesheet = -1;
	for line in cuesheet_content:
		current_track_in_cuesheet += 1
		if re.compile(".*[Tt][Rr][Aa][Cc][Kk] 0?"+str(track)+".*").match(line):
			break
	# See if the next line is index 00, and if so, get and output the pregap if the CU2 format requires it
	if re.compile(".*[Ii][Nn][Dd][Ee][Xx] 0?0.*").match(cuesheet_content[current_track_in_cuesheet+1]) and format_revision == int(2):
		pregap_position = cuesheet_content[current_track_in_cuesheet+1][::-1][:8][::-1][:9]
		if compatibility_mode == True:
			# Add the famous two second offset for PSIO and convert to alternative notation used by Systems Console for tracks
			pregap_position = convert_sectors_to_timecode_with_alternative_notation(convert_timecode_to_sectors(timecode_addition(pregap_position,"00:02:00")))
		# Apply offset if supplied
		if offset_supplied == True and offset_pregaps == True:
			if offset_mode_is_add == True:
				pregap_position = timecode_addition(pregap_position, offset_timecode)
			elif offset_mode_is_add == False:
				pregap_position = timecode_substraction(pregap_position, offset_timecode)
		output = output+"pregap"+str(track).zfill(2)+"  "+pregap_position+"\r\n"
	# Check if this cue sheet uses the PREGAP command, which is bad. We can continue, but...
	elif re.compile(".*[Pp][Rr][Ee][Gg][Aa][Pp].*").match(cuesheet_content[current_track_in_cuesheet+1]) and format_revision == int(2):
		if pregap_command_used_before == False:
			warning("The PREGAP command is used for track "+str(track)+", which requires the software to insert data into the image or disc. This is not supported by Cue2cu2. The pregap will be ignored and a zero length pregap will be noted in the CU2 sheet in order to continue, but the resulting bin/CU2 set might not work as expected or not at all. If possible, please try a Redump compatible version of this image")
			pregap_command_used_before = bool(True)
		elif pregap_command_used_before == True:
			warning("The PREGAP command is also used for track "+str(track)+".")
		if re.compile(".*[Ii][Nn][Dd][Ee][Xx] 0?1.*").match(cuesheet_content[current_track_in_cuesheet+2]):
			pregap_position = cuesheet_content[current_track_in_cuesheet+2][::-1][:8][::-1][:9]
			if compatibility_mode == True:
				# Add the famous two second offset for PSIO and convert to alternative notation used by Systems Console for tracks
				pregap_position = convert_sectors_to_timecode_with_alternative_notation(convert_timecode_to_sectors(timecode_addition(pregap_position,"00:02:00")))
			# Apply offset if supplied
			if offset_supplied == True and offset_pregaps == True:
				if offset_mode_is_add == True:
					pregap_position = timecode_addition(track_position, offset_timecode)
				elif offset_mode_is_add == False:
					pregap_position = timecode_substraction(track_position, offset_timecode)
			output = output+"pregap"+str(track).zfill(2)+"  "+pregap_position+"\r\n"
	elif format_revision == int(2):
		error("Could not find pregap position (index 00) for track "+str(track))
	# Else-If is it index 01? If so, output track start, or get it from the following line
	if re.compile(".*[Ii][Nn][Dd][Ee][Xx] 0?1.*").match(cuesheet_content[current_track_in_cuesheet+1]):
		track_position = cuesheet_content[current_track_in_cuesheet+1][::-1][:8][::-1][:9] # I have no idea what I'm doing
	elif re.compile(".*[Ii][Nn][Dd][Ee][Xx] 0?1.*").match(cuesheet_content[current_track_in_cuesheet+2]):
		track_position = cuesheet_content[current_track_in_cuesheet+2][::-1][:8][::-1][:9]
	else:
		error("Could not find starting position (index 01) for track "+str(track))
	if compatibility_mode == True:
		# Add the famous two second offset for PSIO and convert to alternative notation used by Systems Console for tracks
		track_position = convert_sectors_to_timecode_with_alternative_notation(convert_timecode_to_sectors(timecode_addition(track_position,"00:02:00")))
	# Apply offset if supplied
	if offset_supplied == True and offset_audio == True:
		if offset_mode_is_add == True:
			track_position = timecode_addition(track_position, offset_timecode)
		elif offset_mode_is_add == False:
			track_position = timecode_substraction(track_position, offset_timecode)
	output = output+"track"+str(track).zfill(2)+"   "+track_position+"\r\n"

# Add the end for the last track
if compatibility_mode == True and format_revision == int(1):
	track_end = convert_sectors_to_timecode_with_alternative_notation(convert_timecode_to_sectors(timecode_addition(size,"00:04:00")))
elif compatibility_mode == True and format_revision == int(2):
	track_end = convert_sectors_to_timecode_with_alternative_notation(convert_timecode_to_sectors(timecode_addition(size,"00:02:00")))
else:
	track_end = size
# Apply offset if supplied
if offset_supplied == True and offset_end == True:
	if offset_mode_is_add == True:
		track_end = timecode_addition(track_end, offset_timecode)
	elif offset_mode_is_add == False:
		track_end = timecode_substraction(track_end, offset_timecode)
output = output+"\r\ntrk end   "+track_end


if compatibility_mode == False and stdout == False:
	output = output + "\r\n"

# We are now ready to output our CU2 sheet
if stdout == True:
	if compatibility_mode == True:
		warning("Piping stdout to a file will add a proper linebreak to the last line. While not a problem per se, the CU2 sheet will not be bit identical to Systems Console output")
	print(output)
else:
	# Unless an output file name was specified, derive it from the binary file's filename
	if not cu2sheet:
		cu2sheet = binaryfile[::-1][4:][::-1]+".cu2"
	try:
		cu2file = open(cu2sheet,"wb")
		cu2file.write(output.encode())
		cu2file.close
	except:
		error("Could not write to "+str(cu2sheet))