Rooting is required to change your bootscreen using this method. Root your phone if its not already rooted. Google for it.
If you have rooted your phone..
Use a file explorer like es file explorer to go to the root directory of your phone..
go to system/media, you will find the zip archive named bootanimation.zip there
If you are creating your own bootanimation for the first time or simply want to edit an existing one,
Open the archive, you ll see a folder named part0, sometimes a second folder named part1 or more if the animation has two or more sequences (dividing them up this way can be helpful if you want to add pauses and loop certain sequences, but not others).
These folders contain the frames (images) for each part of the animation. These images will be named in sequential order – something like 00000.jpg, 00001.jpg, 00002.jpg, etc.
In the root of the archive, along side this/these folder(s), will be a txt file named desc.txt.
This text file contains the definition/configuration for the bootanimation.
Here is the contents of an example desc.txt followed by an explanation:
320 480 30
p 1 30 part0
p 0 0 part1
The first line:
320 – sets the width
480 – sets the height
30 – sets the frame rate in frames per second (fps)
The second line defines a part of the animation and is specific to a single folder in the archive):
p – stands for part and defines the first part of the animation in this case.
1 – means to play this part once.
30 – this is the length of a pause on the last frame of this part, expressed in a number frames and is dependent on the frame rate defined in the first line (in this case, 1 sec = 30/30).
part0 – the name of the folder where this sequence of images is located.
The third line defines a second part of the animation and is specific to a single folder in the archive):
p – stands for part and defines the second part of the animation in this case.
0 – means to loop this part indefinitely (until the phone boots).
0 – this is the length of a pause on the last frame of this part, expressed in a number of frames and is dependent on the frame rate defined in the first line (in this case, no pause).
part1 – the name of the folder where this sequence of images is located.
When adding or replacing images or the desc.txt to/in a bootanimation.zip file, be sure to set the Compression Level no compression.