videotestsrc
gst-launch-1.0 videotestsrc pattern=snow ! autovideosink smpte (0) 
snow (1) 
black (2) 
white (3) 
red (4) 
green (5) 
blue (6) 
checkers-1 (7) 
checkers-2 (8) 
checkers-4 (9) 
checkers-8 (10) 
circular (11) 
blink (12) 
smpte75 (13) 
zone-plate (14) 
gamut (15) 
chroma-zone-plate (16) 
solid-color (17) 
ball (18) 
smpte100 (19) 
bar (20) 
pinwheel (21) 
spokes (22) 
gradient (23) 
colors (24) 
smpte-rp-219 (25) 