fix(preview): ffmpeg gets stuck when getting video cover

[ncheng89]

Fixed the issue that ffmepg was stuck in getting the cover, which caused the PHP process to be blocked.

• Resolves: [Bug]: ffmpeg gets stuck when getting video cover #43328

Summary

TODO

• ...

Checklist

• Code is properly formatted
• Sign-off message is added to all commits
• Tests (unit, integration, api and/or acceptance) are included
• Screenshots before/after for front-end changes
• Documentation (manuals or wiki) has been updated or is not required
• Backports requested where applicable (ex: critical bugfixes)

[kesselb]

Good idea to make the movie preview provider more robust by adding a timeout.

I used $cmd = ['/usr/bin/sleep', '60']; for testing.
Seems to work ;)

ffmpeg cannot extract an image for the given file.
That's not a temporary, I guess.

The timeout might help to reduce the impact, but Nextcloud will try to generate the preview again and again and again.
I wonder if we should use/generate a placeholder image for such cases.

We could also use the symfony process component (it's in 3rdparty) that provides this timeout logic already.

Related: #42545

[ncheng89]

通过添加超时功能使电影预览提供程序更加强大是一个好主意。

我用来$cmd = ['/usr/bin/sleep', '60'];测试了。 似乎有效 ;)

ffmpeg 无法提取给定文件的图像。 我猜这不是临时的。

超时可能有助于减少影响，但 Nextcloud 会一次又一次地尝试生成预览。 我想知道我们是否应该针对这种情况使用/生成占位符图像。

我们还可以使用已经提供此超时逻辑的 symfony 进程组件（它在第三方中）。

相关：#42545

Of course, this fix includes the ffmpeg timeout problem. If ffmpeg fails to obtain the cover within the specified time, the task will be terminated and the ffmpeg process will be recycled and released.

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