I'm kinda new to XDA forums.. Not sure if this thread is on right place? Or if it contain relevant information that is worth enough to populate subjects in here. After all admins can just delete this then I will know.
It's easy to change the default bootup animation. This procedure will not change the "Sony" splash screen though, just the "Xperia" inital screen and the following animation:
1- Go to /system/media and download "bootanimation.zip"
2- Extract files on computer. You will see some folders. Inside folders search for the JPEG images of the animation and the "Xperia" splash screen. Tweak images there and put any JPEG you want 9must be same size. You can delete images as to make a shorter animation. I didn't tested placing more frames though, so not sure if it will work.
3- Now comes the trick: Zip all the files again to the new bootanimation.zip but using compression method "store". It will not work using standard or other compression methods.
4- Upload new bootanimation.zip back to /system/media
That's. Enjoy your new boot animation