xiaoxia
fc6ff32376
核心改动： - 渲染完成后从已渲染视频抽帧作为封面，天然带标题（ASS字幕已烧录） - 删除3条旧封面路径：缩略图、候选帧、FFmpeg备用抽帧 - 封面URL持久化到GenerationTask.cover_url - 封面API直接从持久化URL读取
135 lines
4.2 KiB
Python
Executable File
135 lines
4.2 KiB
Python
Executable File
"""视频封面抽帧工具 — 从已渲染视频中抽取帧作为封面。
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统一封面管道：视频渲染时标题已通过 ASS 字幕烧进视频，
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渲染完成后直接从此视频抽帧，封面天然带标题，无需额外叠加逻辑。
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"""
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from __future__ import annotations
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import logging
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import tempfile
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from pathlib import Path
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logger = logging.getLogger(__name__)
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def extract_first_frame(
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video_path: str,
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output_path: str | None = None,
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*,
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width: int = -1,
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height: int = -1,
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timeout: int = 30,
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seek_ratio: float = 0.15,
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min_seek_seconds: float = 1.0,
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) -> str:
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"""抽取视频封面帧（默认取视频时长 15% 处的帧，避开片头纯色画面）。
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因为视频渲染时标题已通过 ASS 字幕烧录，抽取的帧天然带标题。
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Args:
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video_path: 视频文件路径
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output_path: 输出图片路径，不传则用临时文件
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width: 输出宽度（默认 -1，保持原始分辨率）
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height: 输出高度（默认 -1，保持原始分辨率）
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timeout: 超时时间（秒）
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seek_ratio: 抽帧位置占视频时长的比例（默认 0.15，即 15% 处）
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min_seek_seconds: 最小抽帧时间（秒），避免极短视频 seek 到 0
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Returns:
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生成的封面帧文件路径
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Raises:
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RuntimeError: ffmpeg 执行失败或输出文件为空
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"""
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from video_processing.ffmpeg_utils import FFMPEG_BIN, probe_duration, run_ffmpeg
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_is_temp_output = False
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if output_path is None:
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tmp = tempfile.NamedTemporaryFile(suffix=".jpg", delete=False)
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tmp.close()
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output_path = tmp.name
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_is_temp_output = True
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try:
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# 计算抽帧时间点：取视频时长 * seek_ratio，最少 min_seek_seconds 秒
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try:
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duration = probe_duration(video_path)
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seek_time = max(min_seek_seconds, duration * seek_ratio)
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except Exception:
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# probe 失败时 fallback 到第1秒
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seek_time = min_seek_seconds
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# 格式化为 HH:MM:SS.xx
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seek_str = _format_seek_time(seek_time)
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# 构建 scale filter：如果指定了宽高则缩放，否则保持原始分辨率
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if width > 0 or height > 0:
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w_str = str(width) if width > 0 else "-1"
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h_str = str(height) if height > 0 else "-1"
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scale_filter = f"scale={w_str}:{h_str}:force_original_aspect_ratio=decrease,format=yuvj420p"
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else:
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# 保持原始分辨率，只确保格式兼容
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scale_filter = "format=yuvj420p"
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# -ss 放在 -i 前面（input seeking，更快）
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# -vframes 1 只取一帧
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# -q:v 2 jpeg 高质量
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cmd = [
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FFMPEG_BIN,
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"-y",
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"-ss",
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seek_str,
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"-i",
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video_path,
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"-vframes",
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"1",
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"-vf",
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scale_filter,
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"-q:v",
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"2",
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output_path,
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]
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try:
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run_ffmpeg(cmd, capture_output=True, timeout=timeout)
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except Exception:
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# 失败时退回到第0帧兜底
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cmd2 = [
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FFMPEG_BIN,
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"-y",
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"-i",
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video_path,
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"-ss",
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"00:00:00",
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"-vframes",
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"1",
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"-vf",
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scale_filter,
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"-q:v",
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"2",
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output_path,
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]
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run_ffmpeg(cmd2, capture_output=True, timeout=timeout)
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if not Path(output_path).exists() or Path(output_path).stat().st_size == 0:
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raise RuntimeError(f"Cover frame extraction failed: {output_path}")
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return output_path
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except Exception:
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# 失败时清理自己创建的临时文件
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if _is_temp_output and output_path:
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try:
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Path(output_path).unlink(missing_ok=True)
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except Exception:
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pass
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raise
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def _format_seek_time(seconds: float) -> str:
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"""将秒数格式化为 HH:MM:SS.xx 格式。"""
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h = int(seconds // 3600)
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m = int((seconds % 3600) // 60)
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s = seconds % 60
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return f"{h:02d}:{m:02d}:{s:05.2f}"
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