"""Add subtitles to video files."""
import asyncio
from pathlib import Path
from typing import Optional, Literal
from ..config import config
def get_subtitle_style(font_size: int, style_type: str) -> str:
"""Get ASS subtitle style string.
Args:
font_size: Font size
style_type: Style type (outline, shadow, background, glow)
Returns:
ASS subtitle style string
"""
base_style = (
f"FontSize={font_size},"
"FontName=Arial,"
"PrimaryColour=&H00FFFFFF,"
"Bold=0,"
"Italic=0,"
"Alignment=2,"
"MarginV=30"
)
styles = {
"outline": ",Outline=2,OutlineColour=&H00000000,BorderStyle=1,Shadow=1,ShadowColour=&H80000000",
"shadow": ",Outline=1,OutlineColour=&H00000000,BorderStyle=1,Shadow=3,ShadowColour=&H80000000",
"background": ",BorderStyle=3,BackColour=&H80000000,Outline=0,Shadow=0",
"glow": ",Outline=3,OutlineColour=&H40000000,BorderStyle=1,Shadow=0",
}
return base_style + styles.get(style_type, styles["outline"])
async def ffmpeg_add_subtitles(
file_path: str,
subtitle_path: str,
style: Literal["outline", "shadow", "background", "glow"] = "outline",
font_size: int = 24,
output_path: Optional[str] = None,
) -> str:
"""Add subtitles to a video file (burn-in/hardcode).
Args:
file_path: Path to the input video file
subtitle_path: Path to the subtitle file (SRT, ASS, VTT)
style: Subtitle style - "outline" (default), "shadow", "background", or "glow"
font_size: Font size for subtitles (default: 24)
output_path: Optional output file path. If not specified, saves to default output directory.
Returns:
Path to the output video with subtitles
"""
video_path = Path(file_path).expanduser().resolve()
if not video_path.exists():
raise FileNotFoundError(f"Video file not found: {file_path}")
if not video_path.is_file():
raise ValueError(f"Not a file: {file_path}")
sub_path = Path(subtitle_path).expanduser().resolve()
if not sub_path.exists():
raise FileNotFoundError(f"Subtitle file not found: {subtitle_path}")
if not sub_path.is_file():
raise ValueError(f"Not a file: {subtitle_path}")
# Determine output path
if output_path:
out_path = Path(output_path).expanduser().resolve()
else:
output_dir = config.ensure_output_dir()
out_path = output_dir / f"{video_path.stem}_subtitled{video_path.suffix}"
# Get subtitle style
subtitle_style = get_subtitle_style(font_size, style)
# Escape paths for ffmpeg filter
sub_path_escaped = str(sub_path).replace("'", "'\\''").replace(":", "\\:")
subtitle_filter = f"subtitles='{sub_path_escaped}':force_style='{subtitle_style}'"
cmd = [
config.ffmpeg_path,
"-i", str(video_path),
"-vf", subtitle_filter,
"-c:v", "libx264",
"-preset", "medium",
"-crf", "23",
"-c:a", "copy",
"-y",
str(out_path),
]
proc = await asyncio.create_subprocess_exec(
*cmd,
stdout=asyncio.subprocess.PIPE,
stderr=asyncio.subprocess.PIPE,
)
stdout, stderr = await proc.communicate()
if proc.returncode != 0:
raise RuntimeError(f"ffmpeg add subtitles failed: {stderr.decode()}")
return f"Subtitles added successfully: {out_path}"
