162 lines
3.7 KiB
Python
162 lines
3.7 KiB
Python
"""SRT Parser Module
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解析 SRT 字幕文件格式，将字幕转换为结构化的 Segment 对象。
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SRT 格式示例:
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1
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00:00:00,000 --> 00:00:05,000
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第一句字幕内容
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2
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00:00:05,000 --> 00:00:10,000
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第二句字幕内容
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"""
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from __future__ import annotations
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import re
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from dataclasses import dataclass
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from pathlib import Path
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from typing import List
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@dataclass
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class Segment:
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"""字幕分段数据结构
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Attributes:
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id: 字幕序号
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start_time: 开始时间（秒）
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end_time: 结束时间（秒）
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text: 字幕文本
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"""
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id: int
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start_time: float
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end_time: float
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text: str
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# SRT 块正则表达式
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# 格式: 序号\n时间码\n文本(可能多行)\n\n
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SRT_BLOCK_PATTERN = re.compile(
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r'(\d+)\s*\n'
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r'(\d{2}:\d{2}:\d{2},\d{3})\s*-->\s*(\d{2}:\d{2}:\d{2},\d{3})\s*\n'
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r'(.*?)(?=\n\n|\Z)',
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re.DOTALL
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)
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def parse_srt_time(time_str: str) -> float:
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"""解析 SRT 时间格式 (HH:MM:SS,mmm) 为秒数
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Args:
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time_str: SRT 时间字符串，如 "00:05:30,500"
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Returns:
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秒数，如 330.5
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Example:
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>>> parse_srt_time("00:05:30,500")
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330.5
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>>> parse_srt_time("01:02:03,004")
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3723.004
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"""
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# 分割时间和毫秒
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main_part, millis = time_str.rsplit(',', 1)
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hours, minutes, seconds = main_part.split(':')
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total_seconds = (
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int(hours) * 3600 +
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int(minutes) * 60 +
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int(seconds) +
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int(millis) / 1000
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)
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return total_seconds
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def parse_srt(content: str) -> List[Segment]:
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"""解析 SRT 格式字符串
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将 SRT 格式的字幕内容解析为 Segment 对象列表。
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Args:
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content: SRT 格式的字符串内容
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Returns:
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Segment 对象列表
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Raises:
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ValueError: 内容为空或格式无效
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Example:
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>>> content = "1\\n00:00:00,000 --> 00:00:05,000\\n第一句\\n\\n"
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>>> segments = parse_srt(content)
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>>> len(segments)
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1
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>>> segments[0].text
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'第一句'
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"""
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# 检查空内容
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if not content or not content.strip():
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raise ValueError("Empty SRT content")
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segments = []
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# 查找所有 SRT 块
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matches = SRT_BLOCK_PATTERN.findall(content)
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if not matches:
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raise ValueError("Invalid SRT format: no valid blocks found")
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for match in matches:
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try:
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segment_id = int(match[0])
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start_time = parse_srt_time(match[1])
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end_time = parse_srt_time(match[2])
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# 清理文本：移除前后空白，合并多行为单行
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text = ' '.join(match[3].strip().split())
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segment = Segment(
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id=segment_id,
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start_time=start_time,
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end_time=end_time,
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text=text
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)
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segments.append(segment)
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except (ValueError, IndexError) as e:
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# 跳过解析失败的块
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continue
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if not segments:
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raise ValueError("Invalid SRT format: no valid segments parsed")
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return segments
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def parse_srt_file(file_path: Path) -> List[Segment]:
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"""从文件解析 SRT 格式
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读取文件内容并解析为 Segment 对象列表。
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Args:
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file_path: SRT 文件路径
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Returns:
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Segment 对象列表
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Raises:
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FileNotFoundError: 文件不存在
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ValueError: 内容格式无效
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Example:
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>>> from pathlib import Path
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>>> segments = parse_srt_file(Path("subtitles.srt"))
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>>> len(segments)
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10
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"""
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if not file_path.exists():
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raise FileNotFoundError(f"SRT file not found: {file_path}")
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content = file_path.read_text(encoding='utf-8')
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return parse_srt(content)
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