ffmpeg screencapture with xvfb displaying green screen

Question

Using xvfb to run a browser window and want to do a screen recording of that Doing

xvfb-run Firefox http://google.com
ffmpeg -y -r 30 -f x11grab -i :94.0 output.mp4

Getting output as if colors are washed out

Answer 1

Using this option while starting xvfb works

Xvfb :1 -screen 0 1600x1200x24+32