feat(03-01): implement ASRProcessor with official subtitle download

- Create processors module with ASRProcessor class
- Implement _try_official_subtitle for B站字幕下载
- Support process() method with subtitle-first strategy
- Add helper functions for whisper.cpp integration

- All 5 processor tests passing

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
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2026-03-13 19:22:23 +08:00
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"""Processors module for KB Pipeline
This module contains processors for various content transformation tasks:
- ASRProcessor: Audio-to-text conversion (subtitle download + Whisper.cpp)
"""
from .asr import ASRProcessor
__all__ = ["ASRProcessor"]
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"""ASRProcessor - Audio-to-text conversion
Unified processor for B站官方字幕下载 and Whisper.cpp 语音识别.
Follows the pipeline pattern established in Phase 1/2.
Strategy:
1. Try official subtitle first (highest quality, no compute cost)
2. Fall back to Whisper.cpp if no subtitle available
3. Auto-enable speaker diarization if HF_TOKEN is configured
"""
from __future__ import annotations
import asyncio
import json
import logging
import os
import subprocess
from pathlib import Path
from typing import Optional, Dict, Any, List
import aiohttp
from ..config import get_settings
from ..schemas import ASRInput, ASROutput
from ..state import WorkflowStateManager
logger = logging.getLogger(__name__)
class WhisperNotFoundError(RuntimeError):
"""Whisper.cpp 路径未找到"""
pass
def get_whisper_cpp_path() -> str:
"""获取 whisper.cpp 安装路径
检查环境变量 WHISPER_CPP_PATH 或默认路径 ~/whisper.cpp
Returns:
whisper.cpp 目录路径
Raises:
WhisperNotFoundError: 如果路径不存在
"""
# 检查环境变量
path = os.environ.get('WHISPER_CPP_PATH')
if path and os.path.exists(path):
return os.path.expanduser(path)
# 检查默认路径
default = os.path.expanduser('~/whisper.cpp')
if os.path.exists(default):
return default
raise WhisperNotFoundError(
"未找到 whisper.cpp。请设置 WHISPER_CPP_PATH 环境变量或安装到 ~/whisper.cpp"
)
def convert_to_wav(input_path: str, output_path: Optional[str] = None) -> str:
"""使用 ffmpeg 将音频/视频转换为 16kHz WAV 格式
Args:
input_path: 输入文件路径
output_path: 输出文件路径(可选,默认为 input_path_audio.wav)
Returns:
输出 WAV 文件路径
"""
if output_path is None:
base = os.path.splitext(input_path)[0]
output_path = f"{base}_audio.wav"
cmd = [
'ffmpeg', '-y', '-i', input_path,
'-ar', '16000', # 16kHz 采样率
'-ac', '1', # 单声道
'-c:a', 'pcm_s16le', # 16-bit PCM
output_path
]
subprocess.run(cmd, capture_output=True, check=True)
return output_path
class ASRProcessor:
"""ASR 处理器 - 统一字幕下载和语音识别
处理流程:
1. 如果是 B站视频,尝试下载官方字幕
2. 无官方字幕则调用 Whisper.cpp
3. HF_TOKEN 配置时自动启用说话者分离
4. 记录处理状态到 workflow_state.json
Attributes:
STEP_NAME: 步骤名称,用于状态记录
settings: KB 配置
state_manager: 状态管理器(可选)
"""
STEP_NAME = "asr"
def __init__(self, state_manager: Optional[WorkflowStateManager] = None):
"""初始化 ASR 处理器
Args:
state_manager: 状态管理器(可选,用于记录处理状态)
"""
self.settings = get_settings()
self.state_manager = state_manager
async def process(self, input_data: ASRInput) -> ASROutput:
"""执行 ASR 处理
策略:
1. 先尝试官方字幕(仅 B站)
2. 无官方字幕则调用 Whisper
3. 记录状态
Args:
input_data: ASR 输入数据
Returns:
ASR 处理结果
Raises:
Exception: 处理失败时抛出异常
"""
result = None
try:
# Step 1: 尝试官方字幕(仅 B站)
if input_data.platform == "bilibili":
result = await self._try_official_subtitle(input_data)
# Step 2: 无官方字幕则调用 Whisper
if result is None:
result = await self._run_whisper(input_data)
# Step 3: 记录成功状态
if self.state_manager:
state = self.state_manager.load()
if state:
summary = f"tool={result.tool}, segments={len(result.segments)}"
if result.speakers:
summary += f", speakers={len(result.speakers)}"
state.mark_step_completed(self.STEP_NAME, summary)
self.state_manager.save(state)
return result
except Exception as e:
# 记录失败状态(只在所有重试都失败后)
if self.state_manager:
state = self.state_manager.load()
if state:
state.mark_step_failed(self.STEP_NAME, str(e))
self.state_manager.save(state)
raise
async def _try_official_subtitle(self, input_data: ASRInput) -> Optional[ASROutput]:
"""尝试下载 B站官方字幕
Args:
input_data: ASR 输入数据
Returns:
如果找到字幕返回 ASROutput,否则返回 None
Note:
无字幕返回 None(不是抛异常),让流程继续到 Whisper
"""
video_path = Path(input_data.video_path)
output_dir = video_path.parent
base_name = video_path.stem
# 输出文件路径
txt_path = output_dir / f"{base_name}.txt"
srt_path = output_dir / f"{base_name}.srt"
json_path = output_dir / f"{base_name}.json"
async with aiohttp.ClientSession() as session:
try:
# Step 1: 获取 CID
bvid = input_data.content_id
pagelist_url = f"https://api.bilibili.com/x/player/pagelist?bvid={bvid}"
async with session.get(pagelist_url) as resp:
pagelist_data = await resp.json()
pages = pagelist_data.get('data', [])
if not pages:
logger.info(f"No pagelist data for {bvid}")
return None
cid = pages[0].get('cid')
if not cid:
logger.info(f"No cid found for {bvid}")
return None
# Step 2: 获取字幕列表
player_url = f"https://api.bilibili.com/x/player/v2?bvid={bvid}&cid={cid}"
async with session.get(player_url) as resp:
player_data = await resp.json()
subtitle_info = player_data.get('data', {}).get('subtitle', {})
subtitles = subtitle_info.get('list', [])
if not subtitles:
logger.info(f"No official subtitle for {bvid}")
return None
# Step 3: 下载第一个字幕(优先 AI 生成的中文字幕)
subtitle_url = None
for sub in subtitles:
if sub.get('lan', '').startswith('zh'):
subtitle_url = sub.get('subtitle_url')
break
if not subtitle_url and subtitles:
subtitle_url = subtitles[0].get('subtitle_url')
if not subtitle_url:
return None
# 补全 URL
if subtitle_url.startswith('//'):
subtitle_url = f"https:{subtitle_url}"
async with session.get(subtitle_url) as resp:
subtitle_content = await resp.json()
# Step 4: 转换为输出格式
segments = []
text_parts = []
body = subtitle_content.get('body', [])
for i, item in enumerate(body):
start = item.get('from', 0)
end = item.get('to', 0)
content = item.get('content', '')
segments.append({
'id': i,
'start': start,
'end': end,
'text': content
})
text_parts.append(content)
full_text = ' '.join(text_parts)
duration = segments[-1]['end'] if segments else 0
# Step 5: 写入文件
# TXT 格式
txt_path.write_text(full_text, encoding='utf-8')
# SRT 格式
srt_content = self._convert_to_srt(segments)
srt_path.write_text(srt_content, encoding='utf-8')
# JSON 格式
json_data = {
'success': True,
'tool': 'subtitle',
'segments': segments,
'text': full_text,
'duration_seconds': duration
}
json_path.write_text(json.dumps(json_data, ensure_ascii=False, indent=2), encoding='utf-8')
return ASROutput(
success=True,
tool="subtitle",
has_subtitle=True,
output_files={
'txt': str(txt_path),
'srt': str(srt_path),
'json': str(json_path)
},
segments=segments,
text=full_text,
duration_seconds=duration
)
except aiohttp.ClientError as e:
logger.warning(f"Failed to fetch subtitle: {e}")
return None
def _convert_to_srt(self, segments: List[Dict]) -> str:
"""将字幕分段转换为 SRT 格式
Args:
segments: 字幕分段列表,每个包含 start, end, text
Returns:
SRT 格式字符串
"""
lines = []
for i, seg in enumerate(segments, 1):
start_time = self._seconds_to_srt_time(seg['start'])
end_time = self._seconds_to_srt_time(seg['end'])
lines.append(f"{i}")
lines.append(f"{start_time} --> {end_time}")
lines.append(seg['text'])
lines.append("") # 空行
return '\n'.join(lines)
def _seconds_to_srt_time(self, seconds: float) -> str:
"""将秒数转换为 SRT 时间格式 (HH:MM:SS,mmm)"""
hours = int(seconds // 3600)
minutes = int((seconds % 3600) // 60)
secs = int(seconds % 60)
millis = int((seconds % 1) * 1000)
return f"{hours:02d}:{minutes:02d}:{secs:02d},{millis:03d}"
async def _run_whisper(self, input_data: ASRInput) -> ASROutput:
"""执行 Whisper 语音识别
根据 HF_TOKEN 配置自动选择普通模式或说话者分离模式。
Args:
input_data: ASR 输入数据
Returns:
ASR 处理结果
"""
hf_token = self.settings.hf_token.get_secret_value()
if hf_token:
return await self._run_whisper_with_diarization(input_data)
else:
return await self._run_whisper_basic(input_data)
async def _run_whisper_basic(self, input_data: ASRInput) -> ASROutput:
"""执行普通 Whisper.cpp 语音识别
Args:
input_data: ASR 输入数据
Returns:
ASR 处理结果
Raises:
RuntimeError: Whisper.cpp 路径不存在或执行失败
"""
video_path = Path(input_data.video_path)
output_dir = video_path.parent
base_name = video_path.stem
# 获取 Whisper.cpp 路径
try:
whisper_path = get_whisper_cpp_path()
except WhisperNotFoundError as e:
raise RuntimeError(str(e))
# 模型路径
model_path = os.path.join(whisper_path, 'models', 'ggml-base.bin')
if not os.path.exists(model_path):
raise RuntimeError(f"Whisper model not found: {model_path}")
# 转换音频格式
audio_path = convert_to_wav(str(video_path))
temp_audio_created = audio_path != str(video_path)
try:
# 构建 Whisper 命令
output_base = os.path.join(output_dir, base_name)
cmd = [
os.path.join(whisper_path, 'whisper-cli'),
'-m', model_path,
'-f', audio_path,
'-of', output_base,
'-l', 'zh',
'--output-txt', '--output-srt', '--output-json',
]
# 执行 Whisper
result = subprocess.run(cmd, capture_output=True, text=True, timeout=3600)
if result.returncode != 0:
raise RuntimeError(f"Whisper failed: {result.stderr}")
# 解析输出
return self._parse_whisper_output(output_dir, base_name)
finally:
# 清理临时音频文件
if temp_audio_created and os.path.exists(audio_path):
try:
os.remove(audio_path)
except Exception:
pass # 静默失败,不阻塞主流程
def _parse_whisper_output(self, output_dir: Path, base_name: str) -> ASROutput:
"""解析 Whisper 输出文件
Args:
output_dir: 输出目录
base_name: 文件基础名
Returns:
ASR 处理结果
"""
txt_path = output_dir / f"{base_name}.txt"
srt_path = output_dir / f"{base_name}.srt"
json_path = output_dir / f"{base_name}.json"
# 读取 JSON 输出
segments = []
text = ""
duration = 0.0
if json_path.exists():
with open(json_path, 'r', encoding='utf-8') as f:
data = json.load(f)
# Whisper.cpp JSON 格式
if 'transcription' in data:
for i, item in enumerate(data['transcription']):
segments.append({
'id': i,
'start': item.get('offsets', [0, 0])[0] / 1000.0,
'end': item.get('offsets', [0, 0])[1] / 1000.0,
'text': item.get('text', '')
})
text = ' '.join(s['text'] for s in segments)
if segments:
duration = segments[-1]['end']
# 读取文本
if txt_path.exists():
text = txt_path.read_text(encoding='utf-8').strip()
return ASROutput(
success=True,
tool="whisper",
has_subtitle=False,
output_files={
'txt': str(txt_path),
'srt': str(srt_path),
'json': str(json_path)
},
segments=segments,
text=text,
duration_seconds=duration
)
async def _run_whisper_with_diarization(self, input_data: ASRInput) -> ASROutput:
"""执行带说话者分离的 Whisper
Args:
input_data: ASR 输入数据
Returns:
ASR 处理结果,包含说话者信息
"""
# 先运行普通 Whisper
basic_result = await self._run_whisper_basic(input_data)
try:
# 运行说话者分离
diarization_result = run_diarization(input_data.video_path)
# 合并结果
merged_segments = assign_speakers_to_segments(
basic_result.segments,
diarization_result
)
# 提取说话者列表
speakers = list(set(
seg.get('speaker') for seg in merged_segments if seg.get('speaker')
))
return ASROutput(
success=True,
tool="whisper-diarization",
has_subtitle=False,
output_files=basic_result.output_files,
segments=merged_segments,
text=basic_result.text,
duration_seconds=basic_result.duration_seconds,
speakers=sorted(speakers)
)
except ImportError:
logger.warning("pyannote.audio not available, falling back to basic whisper")
return basic_result
except Exception as e:
logger.warning(f"Diarization failed: {e}, falling back to basic whisper")
return basic_result
def run_diarization(audio_path: str, num_speakers: Optional[int] = None) -> Dict[str, List[Dict]]:
"""运行 pyannote.audio 说话者分离
Args:
audio_path: 音频文件路径
num_speakers: 预期说话者数量(可选)
Returns:
说话者时间线字典 {speaker_name: [{start, end}, ...]}
Raises:
ImportError: 如果 pyannote.audio 未安装
RuntimeError: 如果 HF_TOKEN 未配置
"""
hf_token = os.environ.get('HF_TOKEN')
if not hf_token:
raise RuntimeError("需要设置 HF_TOKEN 环境变量以使用说话者分离功能")
from huggingface_hub import login
from pyannote.audio import Pipeline
import torch
login(token=hf_token)
pipeline = Pipeline.from_pretrained("pyannote/speaker-diarization-3.1")
device = torch.device("cuda" if torch.cuda.is_available() else "cpu")
pipeline.to(device)
diarization = pipeline(audio_path, num_speakers=num_speakers)
# 解析结果
speakers = {}
for turn, _, speaker in diarization.itertracks(yield_label=True):
if speaker not in speakers:
speakers[speaker] = []
speakers[speaker].append({
"start": round(turn.start, 2),
"end": round(turn.end, 2)
})
return speakers
def assign_speakers_to_segments(
segments: List[Dict],
diarization: Dict[str, List[Dict]]
) -> List[Dict]:
"""为每个段落分配说话者
根据时间戳匹配说话者分离结果到 Whisper 段落。
Args:
segments: Whisper 段落列表
diarization: 说话者分离结果
Returns:
带有 speaker 字段的段落列表
"""
result = []
for seg in segments:
seg_start = seg.get('start', 0)
seg_end = seg.get('end', 0)
seg_mid = (seg_start + seg_end) / 2
# 找到包含中点时间的说话者
assigned_speaker = None
for speaker, turns in diarization.items():
for turn in turns:
if turn['start'] <= seg_mid <= turn['end']:
assigned_speaker = speaker
break
if assigned_speaker:
break
new_seg = dict(seg)
new_seg['speaker'] = assigned_speaker
result.append(new_seg)
return result