virtual machine – Discrepancy in Video Quality with FFmpeg Encoding on Different Laptops

I’m experiencing an issue where encoding the same video with identical FFmpeg commands on two different laptops results in different output quality. Here’s the command I’m using:

ffmpeg -hwaccel none -loglevel verbose -i test_video.mp4 -r 30 -c:v libx264 -profile:v baseline -level 1.0 -b:v 10000k -s 1920x1080 -preset medium -force_key_frames "expr:gte(t,n_forced*1/30)" -c:a aac -b:a 32k -ac 1 -ar 22050 ENC_test_video.mp4

Both laptops are running VirtualBox 7.0 with the same virtual machine configuration. However, one laptop produces a clear and high-quality encoded video, while the other results in a noisy and lower-quality output.

Details:
VirtualBox Version: 7.0
Operating System inside VMs: Ubuntu 20.04

I’ve ensured that both systems have the same FFmpeg version, yet the output quality differs. What could be causing this discrepancy, and how can I ensure consistent video quality across both systems?

Thanks in advance for your help!