The boot animation for majority of the roms is a zipped folder called bootanimation.zip not boot.img on stock samsung roms the real boot animation is samsungani im not sure where you guys are getting boot animations from a specific important file which contains the kernel to our device called the boot.img im not being a jerk here but if your going to discuss something or ask for assistance try to be clear of what your trying to achieve and what files your looking for if your not sure how the file is called just give a brief description. we are here to help.
Edit: with that being said navigate to system/media and see if you guys have a zipped folder named bootanimation.zip if you dont you guys are using the stock animation method which plays qmg images. its fairly easy to get a stock system to use custom bootanimation.zip files instead of the qmg.