I'm not a developer i'm just trying to do some tutorials in my website and the subject is TWRP on the Galaxy Nexus
i want to take screenshots so i did some searching and found the command adb pull /dev/graphics/fb0
which is pulling the current frame from the recovery in file called fb0 and it's size is 16mb
the next command to turn that file to a jpg pic is ffmpeg -vframes 1 -vcodec rawvideo -f rawvideo -pix_fmt rgba -s 720x1280 -i fb0 -f image2 -vcodec mjpeg fb%d.jpg
which is converting the fb0 to image .. at first it was giving me no such command because the ffmpeg file wasn't there so i did more search and got the files and put the ffmpeg.exe in the fastboot/adb folder and tried the command again but it gives 4 images 3 of them all black and the 4th one with purple color everywhere
the command result was like this
so what do i do wrong ?