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Improve conversion by incorporating color and alignment #17

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68c0aaa
Fix missing positioning
Lucki Mar 9, 2025
ef6f198
Assign colors
Lucki Mar 9, 2025
ad837f4
Assign background colors
Lucki Mar 9, 2025
598e780
Text alignment
Lucki Mar 10, 2025
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112 changes: 95 additions & 17 deletions src/ttml2ssa.py
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Original file line number Diff line number Diff line change
Expand Up @@ -41,8 +41,6 @@ class Ttml2Ssa(object):
'FILM2PAL' : 24/25
}

TOP_MARKER = '{\\an8}'

def __init__(self, shift=0, source_fps=23.976, scale_factor=1, subtitle_language=None):
self.shift = shift
self.source_fps = source_fps
Expand Down Expand Up @@ -72,9 +70,11 @@ def __init__(self, shift=0, source_fps=23.976, scale_factor=1, subtitle_language
self._top_regions_ids = []

self._allowed_style_attrs = (
'backgroundColor',
'color',
'fontStyle',
'fontWeight',
'textAlign',
)

## This variable stores the language ID from the xml file.
Expand Down Expand Up @@ -203,8 +203,8 @@ def extract_rate(s):

# Grab <style>s
# https://www.w3.org/TR/ttml1/#styling-attribute-vocabulary
for styles_container in ttml_dom.getElementsByTagName('styling'):
for style in styles_container.getElementsByTagName('style'):
for styles_container in ttml_dom.getElementsByTagNameNS('*', 'styling'):
for style in styles_container.getElementsByTagNameNS('*', 'style'):
style_id = getattr(
style.attributes.get('xml:id', {}), 'value', None)
if not style_id:
Expand All @@ -214,16 +214,16 @@ def extract_rate(s):
self._italic_style_ids.append(style_id)

# Grab top regions
for layout_container in ttml_dom.getElementsByTagName('layout'):
for region in layout_container.getElementsByTagName('region'):
for layout_container in ttml_dom.getElementsByTagNameNS('*', 'layout'):
for region in layout_container.getElementsByTagNameNS('*', 'region'):
region_id = getattr(
region.attributes.get('xml:id', {}), 'value', None)
if region_id:
# Case 1: displayAlign is in layout -> region
if region.getAttribute('tts:displayAlign') == 'before':
self._top_regions_ids.append(region_id)
# Case 2: displayAlign is in layout -> region -> style
for style in region.getElementsByTagName('style'):
for style in region.getElementsByTagNameNS('*', 'style'):
if style.getAttribute('tts:displayAlign') == 'before':
self._top_regions_ids.append(region_id)

Expand Down Expand Up @@ -287,13 +287,15 @@ def _get_tt_style_attrs(self, node, in_head=False):
return style


def _extract_dialogue(self, nodes, styles=[]):
def _extract_dialogue(self, nodes, styles=[], ass_styles=[]):
"""Extract text content and styling attributes from <p> elements.

Args:
nodes (xml.dom.minidom.Node): List of <p> elements
styles (list): List of style signifiers that should be
applied to each node
ass_styles (list): List of ASS style signifiers that should be
applied to each node

Return:
List of SRT paragraphs (strings)
Expand All @@ -303,6 +305,7 @@ def _extract_dialogue(self, nodes, styles=[]):

for node in nodes:
_styles = []
_ass_styles = []

if node.nodeType == node.TEXT_NODE:
format_str = '{}'
Expand All @@ -317,6 +320,8 @@ def _extract_dialogue(self, nodes, styles=[]):
ot='<{}>'.format(style),
f=format_str)

if ass_styles:
dialogue.append('{' + ''.join(ass_styles) + '}')
dialogue.append(format_str.format(text))

elif node.localName == 'br':
Expand All @@ -330,9 +335,23 @@ def _extract_dialogue(self, nodes, styles=[]):
assoc_italic = style_attrs['style_id'] in self._italic_style_ids
if inline_italic or assoc_italic or node.parentNode.getAttribute('style') == 'AmazonDefaultStyle':
_styles.append('i')
inline_color = self._styles[style_attrs['style_id']]['color']
if inline_color != '':
rgba = Ttml2Ssa._hex_to_rgba(inline_color)
inline_color = Ttml2Ssa._rgba_to_bgr_asshex(rgba)
inline_color_alpha = Ttml2Ssa._rgba_to_alpha_asshex(rgba)
_ass_styles.append('\\1c' + inline_color)
_ass_styles.append('\\1a' + inline_color_alpha)
inline_bcolor = self._styles[style_attrs['style_id']]['background_color']
if inline_bcolor != '':
rgba = Ttml2Ssa._hex_to_rgba(inline_bcolor)
inline_bcolor = Ttml2Ssa._rgba_to_bgr_asshex(rgba)
inline_bcolor_alpha = Ttml2Ssa._rgba_to_alpha_asshex(rgba)
_ass_styles.append('\\3c' + inline_bcolor)
_ass_styles.append('\\3a' + inline_bcolor_alpha)

if node.hasChildNodes():
dialogue += self._extract_dialogue(node.childNodes, _styles)
dialogue += self._extract_dialogue(node.childNodes, _styles, _ass_styles)

return ''.join(dialogue)

Expand All @@ -347,15 +366,32 @@ def _process_parag(self, paragraph):
begin in ms,
end in ms,
text content in Subrip (SRT) format,
position (top or bottom) where the text should appear
position (1..9) where the text should appear
"""

begin = paragraph.attributes['begin'].value
end = paragraph.attributes['end'].value

style = None
if 'style' in paragraph.attributes:
style = paragraph.attributes['style'].value

ms_begin = self._tc.timeexpr_to_ms(begin)
ms_end = self._tc.timeexpr_to_ms(end)

alignment = None
if style and 'text_align' in self._styles[style]:
alignment = self._styles[style]['text_align']

if alignment and alignment == 'center':
alignment = 0
elif alignment and alignment == 'left':
alignment = -1
elif alignment and alignment == 'right':
alignment = 1
else:
alignment = 0

dialogue = self._extract_dialogue(paragraph.childNodes)

# Trim lines and remove empty lines
Expand All @@ -367,7 +403,10 @@ def _process_parag(self, paragraph):
new_text += line
dialogue = new_text

position = 'top' if paragraph.getAttribute('region') in self._top_regions_ids else 'bottom'
# Region information is stored in a numpad layout with numbers 1 to 9
# 1 is the lower left and 9 is the upper right corner
position = 8 if paragraph.getAttribute('region') in self._top_regions_ids else 2
position += alignment

return ms_begin, ms_end, dialogue, position

Expand Down Expand Up @@ -420,7 +459,7 @@ def unescape_text(text):
entry = {}
entry['ms_begin'] = self._tc.timeexpr_to_ms(time1)
entry['ms_end'] = self._tc.timeexpr_to_ms(time2)
entry['position'] = 'top' if m.group('pos') and float(m.group('pos')) < 50 else 'bottom'
entry['position'] = 8 if m.group('pos') and float(m.group('pos')) < 50 else 2
text = ""
while i < len(lines):
line = lines[i].strip()
Expand Down Expand Up @@ -453,8 +492,10 @@ def generate_srt(self):
# Remove <c> </c> tags
text = re.sub('</??c.*?>', '', text)

if self.allow_top_pos and entry['position'] == 'top':
text = Ttml2Ssa.TOP_MARKER + text
position = entry['position']
if not self.allow_top_pos and entry['position'] > 6:
position = position - 6
text = '{\\an' + str(position) + '}' + text

res += srt_format_str.format(entry_count, \
self._tc.ms_to_subrip(entry['ms_begin']), \
Expand All @@ -479,7 +520,7 @@ def generate_vtt(self):
text = re.sub('</??c.*?>', '', text)

pos_str = 'line:90%,end'
if self.allow_top_pos and entry['position'] == 'top':
if self.allow_top_pos and entry['position'] > 6:
pos_str = 'line:10%,start'

res += vtt_format_str.format(self._tc.ms_to_subrip(entry['ms_begin']).replace(',','.'), \
Expand Down Expand Up @@ -516,8 +557,10 @@ def fix_timestamps_separation(entries, timestamp_min_sep):
('<.*?>', '')]:
text = re.sub(tag[0], tag[1], text)

if self.allow_top_pos and entry['position'] == 'top':
text = Ttml2Ssa.TOP_MARKER + text
position = entry['position']
if not self.allow_top_pos and entry['position'] > 6:
position = position - 6
text = '{\\an' + str(position) + '}' + text

res += ssa_format_str.format(self._tc.ms_to_ssa(entry['ms_begin']), self._tc.ms_to_ssa(entry['ms_end']), text)
return res
Expand Down Expand Up @@ -737,6 +780,41 @@ def string_to_color(self, text):
hex_number = "&H" + format(number, '08x').upper()
return hex_number

@staticmethod
def _hex_to_rgba(value: str) -> tuple[int, int, int, int]:
"""Convert a hex RGB(A) string into a RGBA tuple.

Possible string formats:
* ``#RRGGBBAA``
* ``#RRGGBB``
* ``RRGGBBAA``
* ``RRGGBB``
"""
value = value.lstrip('#')
lv = len(value)

if lv == 6: # RGB
r, g, b = tuple(int(value[i:i + 2], base=16) for i in range(0, lv, 2))
return (r, g, b, 255) # Default alpha to 255 (fully opaque)
elif lv == 8: # RGBA
r, g, b, a = tuple(int(value[i:i + 2], base=16) for i in range(0, lv, 2))
return (r, g, b, a)
else:
raise ValueError("Invalid hex color format. Must be 6 or 8 characters long.")

@staticmethod
def _rgba_to_bgr_asshex(rgba: tuple[int, int, int, int]) -> str:
"""Convert RGBA tuple to ASS inline BGR format: ``&HBBGGRR&``"""
return f'&H{rgba[2]:02X}{rgba[1]:02X}{rgba[0]:02X}&'

@staticmethod
def _rgba_to_alpha_asshex(rgba: tuple[int, int, int, int]) -> str:
"""Convert RGBA tuple to ASS inline alpha format: ``&HAA&``"""

# ASS transparency values are inverse to the usual values
# with 255 being fully transparent and 0 being fully opaque.
return f'&H{255 - rgba[3]:02X}&'

@staticmethod
def _snake_to_camel(s):
camel = ''
Expand Down