It is not possible to set the background color (-G) of the canvas when -K is used.

1. When I use this, then the canvas is red

gmt movie main.sh -Nffmpeg1 -T40 -C12cx12cx80 -Z -D12 -Fmp4 -Vi -Gred

2. With this command, then the fade in/out are red. And the canvas during the animation is white. I can't find I way to set the canvas color in a case like this.

gmt movie main.sh -Nffmpeg2 -T40 -C12cx12cx80 -Z -D12 -Fmp4 -Vi -Gred -K+p

3. Here, the inicial and final frames are red even when I used +gyellow. I attach this mp4.

gmt movie main.sh -Nffmpeg3 -T40 -C12cx12cx80 -Z -D12 -Fmp4 -Vi -Gred -K+p+gyellow

Solution

I think that -G should be only be use to the set the color of canvas for the main animation.

Full script

cat << EOF > main.sh
gmt begin
	echo \${MOVIE_FRAME} | gmt text -R0/1/0/1 -JX10c -F+f200p+cCM -B0 -X0 -Y0
gmt end
EOF

gmt movie main.sh -Nffmpeg1 -T40 -C12cx12cx80 -Z  -D12 -Fmp4 -Vi -Gred
gmt movie main.sh -Nffmpeg2 -T40 -C12cx12cx80 -Z  -D12 -Fmp4 -Vi -Gred -K+p
gmt movie main.sh -Nffmpeg3 -T40 -C12cx12cx80 -Z -D12 -Fmp4 -Vi -Gred -K+p+gyellow