FFMPEG Stitch four videos together, then add overlay to result I have four videos (no audio) which I am able to stitch together using this command.
I am also able to add an overlay on a single video with this command.

Is it possible to combine both of these operations with a single ffmpeg command (i.e. stack four 960x540 videos as in the first link, then add a 1920x1080 overlay onto the resulting 1920x1080 video)? Thanks.
Add the overlay to the result of the stacked videos.

Use

ffmpeg -i input0 -i input1 -i input2 -i input3 -i overlay -filter_complex \
"[0:v][1:v]hstack[top]; \
 [2:v][3:v]hstack[bottom]; \
 [top][bottom]vstack[v];[v][4:v]overlay=0:0[v]" \
-map "[v]" output.mp4