我在macOS的 Python 3.13虚拟环境中使用yt-dlp下载视频。但是，对于一个特定的视频（QageNN-V8rY），下载因DownloadError失败。

File "/Users/ashazakhtar/coding/project-idea/.venv/lib/python3.13/site-packages/yt_dlp/YoutubeDL.py", line 1093, in trouble
    raise DownloadError(message, exc_info)
yt_dlp.utils.DownloadError: ERROR: [youtube] QageNN-V8rY: Requested format is not available. Use --list-formats for a list of available formats

我的当前代码：

def transcript_video(self, url):
    with tempfile.TemporaryDirectory() as temp_dir:
        output_path = os.path.join(temp_dir, "audio.m4a")
        cookie_path = os.path.join(settings.BASE_DIR, "www.youtube.com_cookies.txt")
        ydl_opts = {
            "format": "bestaudio[ext=m4a]/bestaudio[ext=webm]/bestaudio",
            "quiet": True,
            "outtmpl": output_path,
            "cookiefile": cookie_path,
            "nocheckcertificate": True,
            "user_agent": "Mozilla/5.0",
            "cookies_readonly": True,
        }

        with YoutubeDL(ydl_opts) as ydl:  # type: ignore
            ydl.download([url])  # type: ignore

        print(f"Audio file size: {os.path.getsize(output_path)} bytes")

        # Send audio file to local FastAPI
        with open(output_path, "rb") as audio_file:
            response = requests.post(
                f"{FASTAPI_BASE_URL}/transcribe",
                files={"file": ("audio.m4a", audio_file, "audio/m4a")},
                timeout=300,  # whisper can be slow on CPU
            )

        response.raise_for_status()
        result = response.json()
        print(f"Transcription done: {result['text'][:100]}...")
        return result["text"]

我尝试过的办法：

1. 我已在浏览器中确认视频URL正确且可访问。
2. 我在虚拟环境中将yt-dlp更新到了最新版本（pip install -U yt-dlp）。
3. 通过命令行运行yt-dlp --list-formats https://www.youtube.com/watch?v=QageNN-V8rY 可以看到可用的格式，但我的Python脚本仍然因格式错误而失败。

如何配置我的ydl_opts字典，使其能够动态选择该视频的“可用中最优格式”，从而避免抛出缺少格式的异常？

解决方案

使用不依赖扩展名的更健壮的选择器：

ydl_opts = {
    "format": "bestaudio/best",
    "quiet": True,
    "outtmpl": output_path,
    "cookiefile": cookie_path,
    "nocheckcertificate": True,
    "user_agent": "Mozilla/5.0",
    "cookies_readonly": True,
}

如果你需要m4a以保持Whisper的一致性，请不要过滤格式——改为转换格式：

ydl_opts = {
    "format": "bestaudio/best",
    "outtmpl": output_path,
    "quiet": True,
    "cookiefile": cookie_path,
    "postprocessors": [{
        "key": "FFmpegExtractAudio",
        "preferredcodec": "m4a",
    }],
}

给你的小贴士：运行这段Python代码，看看yt-dlp实际看到的是什么：

with YoutubeDL({"listformats": True}) as ydl:
    ydl.download([url])