Green screen problem when combining videos using VPP

[Setiuo]

Hi, I write code in Ubuntu and use VPP to combine videos, one is full screen and the other is displayed in a small area. In my debugging process, the full-screen video had a small chance of a green screen. (Sometimes it appears normally, and sometimes it turns green when you shut down the program and restart it. After starting the program, if the display is normal, then the following video will always be normal display; If the startup program displays green screen or green flower screen, then the following video is always abnormal), may I ask if anyone knows the reasons for this situation?
Sorry, I'm not sure whether this is caused by my code irregularities or bugs, so please help analyze it.