feat(scripts): unified Python toolchain, stdlib only
Replaces the scattered TypeScript/shell helpers with one Python toolchain that runs as plain files (`python3 scripts/tools.py <tool> ...`) with no third-party dependencies. New tools - `_common.py` shared plumbing (Report, run, ffmpeg discovery, argparse ergonomics) - `hwprobe.py` what this machine can actually encode (software + hardware) - `srt2ass.py` SRT -> ASS, the missing step between lrc2srt and baking - `ffmpeg_tools.py` mux / bake / still / strip / probe, with hardware encode - `bom_gen.py` BOM generator, ported from scripts/bom-gen.ts - `tools.py` dispatcher so any tool is one command away - `README.md` usage for all of the above Rewritten - `lrc2srt.py` now handles multiple timestamps per line, timestamp-less cue lines and blank/comment lines, and survives malformed input. The legacy version emitted an empty cue plus a stray cue for every line. Hardware encoding This host is AMD (Strix Halo, VCN 4.0.5), so nvenc in the legacy notes is reference only. `hwprobe.py` probes and reports what genuinely works here: VA-API via /dev/dri/renderD128 gives h264_vaapi, hevc_vaapi and av1_vaapi. `ffmpeg_tools.py --video auto` picks the hardware encoder when the render node is usable and falls back to libx264/libx265 when it is not. Two bugs found and fixed while wiring this up: - the VA-API capability probe fed frames straight to the encoder without `format=nv12,hwupload`, so ffmpeg failed with "Function not implemented" and the toolchain silently fell back to software on a machine where hardware works. VA-API encoders only accept GPU-resident frames; the probe now uploads. - `bake --video copy` only failed when the copied stream happened to be VA-API. Burning subtitles always changes pixels, so it now refuses `copy` outright with a clear message. Also makes -q/-n usable on either side of the mode word, and ignores __pycache__ in .gitignore.
This commit is contained in:
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"""Convert an SRT subtitle file to ASS (Advanced SubStation Alpha).
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Stdlib only. Handles the constructs that actually appear in song subtitles:
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multi-line cues, ``{\\an8}``-style override blocks passed through untouched,
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and the SRT quirks (CRLF, BOM, cue numbers, blank-line separators).
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Usage::
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python3 scripts/srt2ass.py song.srt song.ass
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python3 scripts/srt2ass.py lyrics/*.srt --out-dir build/ # batch
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python3 scripts/srt2ass.py song.srt --style-font "Noto Sans" --style-size 64
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"""
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from __future__ import annotations
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import argparse
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import os
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import re
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import sys
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from dataclasses import dataclass
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if __package__ in (None, ""):
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sys.path.insert(0, os.path.dirname(os.path.abspath(__file__)))
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from _common import ( # type: ignore[import-not-found]
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Die,
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Report,
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add_common_arguments,
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glob_files,
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main_wrapper,
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)
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else: # pragma: no cover
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from ._common import (
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Die,
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Report,
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add_common_arguments,
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glob_files,
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main_wrapper,
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)
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# --------------------------------------------------------------------------- #
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# Timestamps
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# --------------------------------------------------------------------------- #
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_SRT_TIME_RE = re.compile(
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r"(?P<h>\d{1,2}):(?P<m>\d{2}):(?P<s>\d{2})[,.](?P<ms>\d{1,3})"
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)
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def parse_srt_time(stamp: str) -> float:
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"""``00:01:02,500`` (or ``00:01:02.5``) to seconds."""
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match = _SRT_TIME_RE.search(stamp.strip())
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if not match:
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raise Die(f"unparseable SRT timestamp: {stamp!r}")
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ms = match.group("ms").ljust(3, "0")[:3]
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return (
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int(match.group("h")) * 3600
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+ int(match.group("m")) * 60
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+ int(match.group("s"))
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+ int(ms) / 1000
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)
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def format_ass_time(seconds: float) -> str:
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"""Seconds to ASS ``H:MM:SS.cc`` (centiseconds, single-digit hour)."""
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if seconds < 0:
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seconds = 0.0
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total_cs = int(round(seconds * 100))
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hours, remainder = divmod(total_cs, 360_000)
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minutes, remainder = divmod(remainder, 6_000)
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secs, centis = divmod(remainder, 100)
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return f"{hours}:{minutes:02d}:{secs:02d}.{centis:02d}"
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# --------------------------------------------------------------------------- #
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# Parsing
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# --------------------------------------------------------------------------- #
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@dataclass
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class Cue:
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index: int
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start: float
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end: float
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lines: list[str]
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def text(self, line_sep: str = r"\N") -> str:
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return line_sep.join(self.lines)
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def strip_bom(text: str) -> str:
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return text[1:] if text.startswith("\ufeff") else text
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def parse_srt(content: str) -> list[Cue]:
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"""Parse SRT text into cues. Tolerates CRLF, BOM, and missing cue numbers."""
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content = strip_bom(content).replace("\r\n", "\n").replace("\r", "\n")
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blocks = re.split(r"\n\s*\n", content)
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cues: list[Cue] = []
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auto_index = 0
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for block in blocks:
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lines = block.strip("\n").split("\n")
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if not lines or not any(line.strip() for line in lines):
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continue
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index: int | None = None
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if lines[0].strip().isdigit():
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index = int(lines[0].strip())
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lines = lines[1:]
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if not lines:
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continue
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if "-->" not in lines[0]:
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# Not a cue (stray header, WEBVTT marker, ...). Skip it quietly.
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continue
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start_raw, _, end_raw = lines[0].partition("-->")
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start = parse_srt_time(start_raw)
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end = parse_srt_time(end_raw)
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body = [line for line in lines[1:] if line.strip()]
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if not body:
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# A cue with a timestamp but no text: pure gap in the lyrics. Emitting
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# it would produce an empty subtitle block, so drop it — the previous
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# cue simply holds until the next one.
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continue
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auto_index += 1
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cues.append(Cue(index=index or auto_index, start=start, end=end, lines=body))
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return cues
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# --------------------------------------------------------------------------- #
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# ASS output
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# --------------------------------------------------------------------------- #
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#: ASS uses US-ASCII-with-code-page-1252 in practice; karaoke/Japanese needs 1.
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ASS_CODEPAGES = {
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"ascii": 0,
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"latin1": 0,
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"cp1252": 0,
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"shift_jis": 1,
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"sjis": 1,
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"gbk": 134,
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"utf-8": 1,
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"utf8": 1,
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}
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ASS_HEADER = """[Script Info]
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; Generated by scripts/srt2ass.py — edit the source SRT, not this file.
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Title: {title}
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ScriptType: v4.00+
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WrapStyle: {wrap_style}
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ScaledBorderAndShadow: yes
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YCbCr Matrix: TV.709
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PlayResX: {width}
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PlayResY: {height}
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[V4+ Styles]
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Format: Name, Fontname, Fontsize, PrimaryColour, SecondaryColour, OutlineColour, BackColour, Bold, Italic, Underline, StrikeOut, ScaleX, ScaleY, Spacing, Angle, BorderStyle, Outline, Shadow, Alignment, MarginL, MarginR, MarginV, Encoding
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Style: Default,{font},{size},{primary},{secondary},{outline_colour},{back},{bold},{italic},0,0,100,100,{spacing},0,1,{border},{shadow},{alignment},{margin_l},{margin_r},{margin_v},{encoding}
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[Events]
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Format: Layer, Start, End, Style, Name, MarginL, MarginR, MarginV, Effect, Text
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"""
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@dataclass
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class AssStyle:
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"""The subset of the Default style we expose on the CLI."""
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font: str = "Arial"
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size: int = 48
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primary: str = "&H00FFFFFF" # white, fully opaque
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secondary: str = "&H000000FF"
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outline_colour: str = "&H00000000"
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back: str = "&H00000000"
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bold: int = -1
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italic: int = 0
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spacing: float = 0.0
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border: float = 2.0
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shadow: float = 1.0
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alignment: int = 2 # 2 = bottom centre
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margin_l: int = 40
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margin_r: int = 40
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margin_v: int = 60
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encoding: int = 1
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def render_ass(
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cues: list[Cue],
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*,
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style: AssStyle,
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width: int,
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height: int,
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title: str,
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wrap_style: int = 0,
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) -> str:
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header = ASS_HEADER.format(
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title=title.replace("\n", " ") or "Untitled",
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wrap_style=wrap_style,
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width=width,
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height=height,
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font=style.font,
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size=style.size,
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primary=style.primary,
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secondary=style.secondary,
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outline_colour=style.outline_colour,
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back=style.back,
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bold=style.bold,
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italic=style.italic,
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spacing=style.spacing,
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border=style.border,
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shadow=style.shadow,
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alignment=style.alignment,
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margin_l=style.margin_l,
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margin_r=style.margin_r,
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margin_v=style.margin_v,
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encoding=style.encoding,
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)
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events = []
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for cue in cues:
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text = cue.text()
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# ASS treats commas as field separators in the Text column, but only the
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# first 9 commas matter — ffmpeg/libass handles commas inside Text fine as
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# long as the Format line lists Text last, which it does above.
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events.append(
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"Dialogue: 0,{start},{end},Default,,0,0,0,,{text}".format(
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start=format_ass_time(cue.start),
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end=format_ass_time(cue.end),
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text=text,
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)
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)
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return header + "\n".join(events) + "\n"
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# --------------------------------------------------------------------------- #
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# CLI
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# --------------------------------------------------------------------------- #
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def build_parser() -> argparse.ArgumentParser:
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parser = argparse.ArgumentParser(
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prog="srt2ass",
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description="Convert SRT subtitles to ASS, ready for ffmpeg's ass= filter.",
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epilog=(
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"Then bake with: ffmpeg -vf \"ass=out.ass\" -i in.mp4 ... "
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"(or scripts/ffmpeg_tools.py bake)"
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),
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)
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add_common_arguments(parser)
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parser.add_argument("inputs", nargs="+", metavar="INPUT", help="SRT file(s) to convert")
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parser.add_argument(
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"-o",
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"--output",
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metavar="FILE",
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help="output .ass path (single input only; default: alongside the input)",
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)
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parser.add_argument(
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"--out-dir",
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metavar="DIR",
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help="write every output into this directory (created if missing)",
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)
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style = parser.add_argument_group("style")
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style.add_argument("--style-font", default="Arial", help="font name (default: Arial)")
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style.add_argument("--style-size", type=int, default=48, help="font size (default: 48)")
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style.add_argument(
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"--style-alignment",
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type=int,
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default=2,
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choices=range(1, 10),
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metavar="N",
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help="ASS numpad alignment 1-9 (default: 2, bottom centre)",
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)
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style.add_argument("--style-margin-v", type=int, default=60, help="vertical margin (default: 60)")
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style.add_argument("--style-outline", type=float, default=2.0, help="outline width (default: 2)")
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style.add_argument("--style-shadow", type=float, default=1.0, help="shadow depth (default: 1)")
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style.add_argument("--style-bold", action=argparse.BooleanOptionalAction, default=True)
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style.add_argument("--style-italic", action=argparse.BooleanOptionalAction, default=False)
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canvas = parser.add_argument_group("canvas")
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canvas.add_argument("--width", type=int, default=1920, help="PlayResX (default: 1920)")
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canvas.add_argument("--height", type=int, default=1080, help="PlayResY (default: 1080)")
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canvas.add_argument(
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"--title",
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default=None,
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help="ASS Title field (default: the output filename)",
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)
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return parser
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def convert_one(src: str, dest: str, args: argparse.Namespace, report: Report) -> tuple[int, int]:
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try:
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with open(src, "r", encoding="utf-8-sig", errors="replace") as handle:
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content = handle.read()
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except OSError as exc:
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raise Die(f"cannot read {src}: {exc.strerror}") from exc
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cues = parse_srt(content)
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if not cues:
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report.warn(f"{src}: no cues parsed — is this really an SRT file?")
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style = AssStyle(
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font=args.style_font,
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size=args.style_size,
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alignment=args.style_alignment,
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margin_v=args.style_margin_v,
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border=args.style_outline,
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shadow=args.style_shadow,
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bold=-1 if args.style_bold else 0,
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italic=-1 if args.style_italic else 0,
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)
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title = args.title or os.path.splitext(os.path.basename(dest))[0]
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document = render_ass(
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cues,
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style=style,
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width=args.width,
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height=args.height,
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title=title,
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)
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if args.dry_run:
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report.info(f"[dry-run] would write {dest} ({len(cues)} cues)")
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return len(cues), 0
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os.makedirs(os.path.dirname(os.path.abspath(dest)), exist_ok=True)
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with open(dest, "w", encoding="utf-8", newline="\n") as handle:
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handle.write(document)
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report.ok(f"{src} -> {dest} ({len(cues)} cues)")
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return len(cues), 0
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@main_wrapper
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def main() -> int:
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args = build_parser().parse_args()
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report = Report(quiet=args.quiet)
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if args.output and len(args.inputs) > 1:
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raise Die("--output takes a single input; use --out-dir for batches")
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total = 0
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for src in args.inputs:
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if not os.path.isfile(src):
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raise Die(f"no such file: {src}")
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stem = os.path.splitext(os.path.basename(src))[0]
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if args.output:
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dest = args.output
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elif args.out_dir:
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dest = os.path.join(args.out_dir, stem + ".ass")
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else:
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dest = os.path.splitext(src)[0] + ".ass"
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cues, _ = convert_one(src, dest, args, report)
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total += cues
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if len(args.inputs) > 1:
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report.info(f"{total} cues across {len(args.inputs)} file(s)")
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return 0
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if __name__ == "__main__":
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raise SystemExit(main())
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Reference in New Issue
Block a user