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104 lines
3.7 KiB
Python
104 lines
3.7 KiB
Python
"""
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ffmpeg / ffprobe 薄封装：所有对外部进程的调用都集中在这里，统一做错误检查。
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设计要点：
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- run() 捕获非零退出码并抛出带 stderr 的清晰异常（而非让 traceback 泄漏）；
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- 提供 probe_duration / probe_streams，供 Reviewer 与验证环节读取成片信息；
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- extract_frame 把某一时间点抽成一张 PNG（缩放到 512 宽以节省 Vision token）。
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"""
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import json
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import os
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import shutil
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import subprocess
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# macOS 自带字体；换平台时改这里即可（Linux 常见 DejaVuSans.ttf）。
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FONT_CANDIDATES = [
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"/System/Library/Fonts/Supplemental/Arial.ttf",
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"/usr/share/fonts/truetype/dejavu/DejaVuSans.ttf",
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"/Library/Fonts/Arial.ttf",
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]
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def find_font() -> str:
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for p in FONT_CANDIDATES:
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if os.path.exists(p):
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return p
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return "" # drawtext 会退化为默认字体
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def ensure_ffmpeg():
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"""启动前自检：ffmpeg / ffprobe 是否可用，给出清晰中文报错。"""
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for tool in ("ffmpeg", "ffprobe"):
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if shutil.which(tool) is None:
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raise RuntimeError(
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f"未找到 {tool}，本项目用 ffmpeg 完成实际剪辑。\n"
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f" macOS: brew install ffmpeg\n"
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f" Ubuntu: sudo apt install ffmpeg"
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)
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def run(cmd, desc="ffmpeg 命令"):
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"""执行命令，失败时抛出带 stderr 尾部的异常。"""
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proc = subprocess.run(cmd, capture_output=True, text=True)
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if proc.returncode != 0:
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tail = "\n".join(proc.stderr.strip().splitlines()[-8:])
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raise RuntimeError(f"{desc} 执行失败（exit={proc.returncode}）：\n{tail}")
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return proc
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def probe_duration(path: str) -> float:
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"""返回视频时长（秒）。文件缺少时长元数据时 ffprobe 输出 N/A，给出清晰报错。"""
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proc = run(
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["ffprobe", "-v", "error", "-show_entries", "format=duration",
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"-of", "default=noprint_wrappers=1:nokey=1", path],
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desc="ffprobe 读取时长",
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)
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out = proc.stdout.strip()
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if not out or out == "N/A":
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raise RuntimeError(f"ffprobe 无法读取时长（文件缺少时长元数据或不是音视频文件）：{path}")
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return float(out)
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def probe_streams(path: str) -> dict:
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"""返回 ffprobe 的 JSON（format + streams），用于打印成片信息。"""
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proc = run(
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["ffprobe", "-v", "error", "-show_format", "-show_streams",
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"-of", "json", path],
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desc="ffprobe 读取流信息",
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)
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return json.loads(proc.stdout)
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def format_probe(path: str) -> str:
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"""把成片信息格式化成一行行的人类可读文本（用于验证输出）。"""
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info = probe_streams(path)
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fmt = info.get("format", {})
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lines = [
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f" 文件: {os.path.basename(path)}",
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f" 时长: {float(fmt.get('duration', 0)):.2f}s",
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f" 容器: {fmt.get('format_name', '?')}",
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f" 大小: {int(fmt.get('size', 0)) / 1024:.1f} KB",
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]
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for s in info.get("streams", []):
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if s.get("codec_type") == "video":
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lines.append(
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f" 视频流: {s.get('codec_name')} {s.get('width')}x{s.get('height')} "
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f"@ {s.get('r_frame_rate')} fps"
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)
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elif s.get("codec_type") == "audio":
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lines.append(
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f" 音频流: {s.get('codec_name')} {s.get('sample_rate')}Hz "
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f"{s.get('channels')}ch"
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)
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return "\n".join(lines)
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def extract_frame(video: str, t: float, out_png: str, width: int = 512):
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"""抽取 t 秒处的一帧，缩放到 width 宽存为 PNG。"""
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run(
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["ffmpeg", "-y", "-ss", f"{t:.3f}", "-i", video,
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"-frames:v", "1", "-vf", f"scale={width}:-1", out_png],
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desc=f"抽帧 t={t:.1f}s",
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)
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return out_png
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