Convert WEBP to MP4

webp2mp4.sh

#!/bin/sh

## Quick script to convert webp files to mp4. Makes use of webpmux, ImageMagick and ffmpeg

input=$1
output_base=/tmp
output_file=output.mp4
regex="Number of frames: ([0-9]+)"
info=`webpmux -info "$1"`

if [[ $info =~ $regex ]]
then
  rm "$output_base/frame_*.png"
  frame_count="${BASH_REMATCH[1]}"
  frame_count=$(($frame_count))

  for idx in $(seq -f '%02g' 01 $frame_count); do
    # Extract the frames from the webp
    webpmux -get frame $idx "$1" -o "$output_base/frame_$idx.png"
    # Use ImageMagick to convert the PNG to PNG, since the one outputted by webpmux seems unsupported by ffmpeg
    convert "$output_base/frame_$idx.png" "$output_base/frame_$idx.png"
  done  
  
  # Take the frames and assemble the MP4. We need to tune the FPS, since right now it is hardcoded
  ffmpeg -framerate 5 -pattern_type glob -i "$output_base/"'frame_*.png' -c:v libx264 -pix_fmt yuv420p "$output_file"
fi