KaraokeTestudaiBackend/subtitle_generator.py

# Substation Alpha (ASS) generation

# Colour values are &HAABBGGRR, &HBBGGRR, or &HAA.
# Alpha is actually inverted, i.e. transparency - FF is transparent, 00 is opaque.

ass_preamble = '''[Script Info]
ScriptType: v4.00+
WrapStyle: 0
ScaledBorderAndShadow: yes
YCbCr Matrix: TV.709
PlayResX: {PlayResX}
PlayResY: {PlayResY}

[V4+ Styles]
Format: Name, Fontname, Fontsize, PrimaryColour, SecondaryColour, OutlineColour, BackColour, Bold, Italic, Underline, StrikeOut, ScaleX, ScaleY, Spacing, Angle, BorderStyle, Outline, Shadow, Alignment, MarginL, MarginR, MarginV, Encoding
Style: Default,Arial,72,&H002A0A00,&H000019FF,&H00FFFFFF,&H00000000,0,0,0,0,100,100,0,0,1,2.5,0,8,30,30,25,1
Style: Kanji,Migu 1P,{KanjiSize},&H{KaraokeColourPast},&H{KaraokeColourFuture},&H00FFFFFF,&H00000000,0,0,0,0,100,100,0,0,1,4.0,0,2,30,30,25,1
Style: Furigana,Migu 1P,{FuriSize},&H{KaraokeColourPast},&H{KaraokeColourFuture},&H00FFFFFF,&H00000000,0,0,0,0,100,100,0,0,1,2.5,0,2,30,30,0,1
Style: Romaji,Migu 1P,{RomajiSize},&H{KaraokeColourPast},&H{KaraokeColourFuture},&H00FFFFFF,&H00000000,0,0,0,0,100,100,0,0,1,2.5,0,8,30,30,25,1
Style: Translation,Migu 1P,{TranslationSize},&H00FFFFFF,&H000019FF,&H00000000,&H00000000,0,1,0,0,100,100,0,0,1,1.0,3,8,30,30,25,1

[Events]
Format: Layer, Start, End, Style, Name, MarginL, MarginR, MarginV, Effect, Text
'''

format_defaults = {
	'PlayResX': 1280,
	'PlayResY': 720,
	'TranslationSize': 48,
	'RomajiSize': 60,
	'KanjiSize': 72,
	'FuriSize': 36,
	'KaraokeColourFuture': '000019FF',
	'KaraokeColourPast': 'E02A0A00',
}

def seconds_to_timestamp(t: float) -> str:
	minutes, seconds = divmod(t, 60)
	hours, minutes = divmod(minutes, 60)
	return f'{int(hours):02}:{int(minutes):02}:{seconds:05.2f}'

from format import LyricTrack
from japanese_converters import kana_to_syllable_list
def generate_ass(filename: str, lyric_track: LyricTrack, format_overloads: dict = None):
	format_dict = format_defaults.copy()
	if format_overloads:
		format_dict.update(format_overloads)
	preamble = ass_preamble.format(**format_dict)

	# Kanji Furigana layout stuff
	size_kanji_x = format_dict['KanjiSize']  # TODO: work out scaling factor for fullwidth from point size
	size_furi_x = format_dict['FuriSize']  # TODO: work out scaling factor for fullwidth from point size
	res_x = format_dict['PlayResX']

	with open(filename, 'w') as file:
		file.write(preamble)
		t = 68.0  # placeholder
		for line in lyric_track.lines:
			t0 = seconds_to_timestamp(t)
			timestamps = line.get_timestamps(0.5, t)
			centiseconds = line.get_karaoke_centiseconds(0.5)
			t = timestamps[-1] + 1.0  # placeholder
			t1 = seconds_to_timestamp(t)
			sub_preamble = f'Dialogue: 0,{t0},{t1}'

			# Translation line is easy and static
			file.write(f'{sub_preamble},Translation,,,,,,{line.translated_line}\n')

			# Romaji line is also easy, just intersperse durations
			romaji_line = f'{{\\k{centiseconds[0]}}}'
			i = 0  # syllable counter
			for syl in line.romaji_syllables:
				if not syl.strip():
					romaji_line += f'{{\\k0}}{syl}'
					continue
				romaji_line += f'{{\\K{centiseconds[i+1]-centiseconds[i]}}}{syl}'
				i += 1
			file.write(f'{sub_preamble},Romaji,,,,,,{romaji_line}\n')

			# Now for the kanji and furi lines...
			kanji_plain_str = ''.join([b.kanji for b in line.furi_blocks])
			full_kanji_width = len(kanji_plain_str) * size_kanji_x
			kanji_line = f'{{\\k{centiseconds[0]}}}'
			kanji_line_progress = 0  # increment as we go, to track furi position
			furi_lines = []
			i = 0  # syllable counter
			for furi_block in line.furi_blocks:
				if len(furi_block.furi) == 0:  # kana or punctuation, nice and simple!
					syls = kana_to_syllable_list(furi_block.kanji)
					for syl in syls:
						if len(syl.strip()) == 0:  # don't time spaces
							kanji_line += f'{{\\k0}}{syl}'
							kanji_line_progress += len(syl)
						else:
							kanji_line += f'{{\\K{centiseconds[i+1]-centiseconds[i]}}}{syl}'
							kanji_line_progress += len(syl)
							i += 1
				else:  # Kanji block
					i0 = i  # Store this to later calculate block time for the kanji
					syls = kana_to_syllable_list(furi_block.furi)
					furi_line = f'{{\\k{centiseconds[i]}}}'
					furi_chars = 0
					for syl in syls:
						furi_line += f'{{\\K{centiseconds[i+1]-centiseconds[i]}}}{syl}'
						furi_chars += len(syl)
						i += 1
					# Need to calculate kanji block position and span to typeset the furigana above it
					k = furi_block.kanji
					k_start = kanji_line_progress
					kanji_line_progress += len(k)
					k_end = kanji_line_progress
					target_middle_x = (size_kanji_x * (k_end+k_start)/2) - (full_kanji_width/2)  # x=0 at center
					furi_width = furi_chars * size_furi_x
					margin_l = 0 if target_middle_x < 0 else int(target_middle_x*1.57)
					margin_r = 0 if target_middle_x > 0 else int(-target_middle_x*1.57)
					furi_lines.append(f'{sub_preamble},Furigana,,{margin_l},{margin_r},,,{furi_line}\n')
					kanji_line += f'{{\\K{centiseconds[i]-centiseconds[i0]}}}{k}'
			file.write(f'{sub_preamble},Kanji,,,,,,{kanji_line}\n')
			for line in furi_lines:
				file.write(line)

example_layout = r'''
Dialogue: 0,0:01:08.00,0:01:26.00,Kanji,,,,,,{\k0}{\K100}雨{\K100}や{\K100}雪{\K100}が{\K100}天{\K100}から{\K100}降{\K100}って{\K100}地{\K100}を{\K100}潤{\K100}し　{\K100}芽{\K100}を{\K100}出{\K100}さ{\K100}せ{\K100}る
Dialogue: 0,0:01:08.00,0:01:26.00,Furigana,,   0,1130,,,{\k0}{\K100}あめ
Dialogue: 0,0:01:08.00,0:01:26.00,Furigana,,   0, 900,,,{\k200}{\K100}ゆき
Dialogue: 0,0:01:08.00,0:01:26.00,Furigana,,   0, 700,,,{\k400}{\K100}てん
Dialogue: 0,0:01:08.00,0:01:26.00,Furigana,,   0, 370,,,{\k600}{\K100}ふ
Dialogue: 0,0:01:08.00,0:01:26.00,Furigana,,   0,   0,,,{\k800}{\K100}ち
Dialogue: 0,0:01:08.00,0:01:26.00,Furigana,, 260,   0,,,{\k1000}{\K100}うるお
Dialogue: 0,0:01:08.00,0:01:26.00,Furigana,, 570,   0,,,{\k1200}{\K100}め
Dialogue: 0,0:01:08.00,0:01:26.00,Furigana,, 800,   0,,,{\k1400}{\K100}だ
Dialogue: 0,0:01:08.00,0:01:26.00,Translation,,,,,,Rain and snow fall from the heavens. Moisten the earth and make it sprout
Dialogue: 0,0:01:08.00,0:01:26.00,Romaji,,,,,,{\K0}{\K100}ame {\K100}ya {\K100}yuki {\K100}ga {\K100}ten {\K100}kara {\K100}fu{\K100}tte {\K100}chi {\K100}wo {\K100}uruo{\K100}shi {\K100}me {\K100}wo {\K100}da{\K100}sa {\K100}se{\K100}ru
'''