If you're looking to improve or optimize something, please provide more context about what you're trying to accomplish.
INPUT="$1" BASE="$2%.*" # strip extension for naming pppd515mp4 better
By using RF 18 and the "Slow" preset, HandBrake analyzes the motion vectors in PPPD-515 uniquely, preserving the grain and fine details that a standard fast-encode destroys. The resulting 5-6GB file will blow a standard 3GB file out of the water. If you're looking to improve or optimize something,