[Ffmpeg-devel] Input image format for encoding...

[Mat]

Hi all.
I'm working with libavformat to make MP4 movies.
I can choose the image format in input...
For the system load, is it better RGB 32 ( RGBA ) or RGB 24 with ffmpeg lib?
I suppose it works better with a 4-bytes image format than a 3-bytes 
image format, right?
( the increment of the raw image size is not a problem in my application )
Greetings,
-Mat-