MoviePy write_videofile not working under Flask

[fanchessfan]

Expected Behavior

This code works fine outside flask. A correct video is generated in the disk and I can playback it properly with normal playback tools in Windows.

Actual Behavior

Flask is a Python HTML webpage tool. However, when it is integrated in flask, I got a blank video. The resolution and frame duration are correct. However, the frames are blank with red color.

Steps to Reproduce the Problem

Specifications

• Python Version: 3.10.5
• Moviepy Version: latest
• Platform Name: Windows
• Platform Version: Windows 10

[keikoro]

Please provide code alongside your issue report. It sounds like Flask is interfering but it's impossible to tell how without seeing what you are doing.