[FFmpeg-user] Set a background color to a mosaic

[Grégory S]

Hi,

i use FFMpeg to create a mosaic.
It works but the background color of the mosaic of my output video is green
by default.
How can i modify my command line in order to have a black color as
background for my mosaic ?

"ffmpeg.exe -i C:/source/video1.mp4 -i C:/source/video2.mp4 -filter_complex
"nullsrc=size=1920x1080 [base]; [0:v] setpts=PTS-STARTPTS, scale=960x540
[upperleft]; [1:v] setpts=PTS-STARTPTS, scale=960x540 [upperright];
[base][upperleft] overlay=eof_action=repeat:x=480 [tmp1];
[tmp1][upperright] overlay=shortest=1:x=480:y=540" -map 0:a -sn -c:v
libx264 -y C:\temp\output.mkv"

Thanks,
Regards,
Grégory