liquid.sh

#!/bin/bash

# This script content aware/steam carves frames from the provided video.
# It works by exploding each frame into a bmp. Passing each bmp through
# imgagemagick's convert-im6 program set to screw with each frame.
# The lastly, combine the frames back into a video with the audio from
# to source video file.

# As you can see, most of this script is inspired by what's found at
# https://gitgud.io/-/snippets/498, In-fact the ffprobe and last ffmpeg
# command was copied over. My version just adds some extra bits to
# improve my "meme" production.



# How many processes should we run until we wait for them to complete.
maxProcesses=18


## === Prepare to do processing ===

# Configure glob to return nothing if nothing is found.
shopt -s nullglob

# Get the filename from the 1st argument.
filename="${1%.*}"

# Prepare our directories for the frames.
mkdir ./frames
mkdir ./frames/"$filename"
mkdir ./frames/"$filename"/liquid

# Grab the FPS from the source video (1st arg.) as we need it to reconstruct
# the video at the end.
fps=$(ffprobe -v 0 -of csv=p=0 -select_streams v:0 -show_entries stream=r_frame_rate "$1")

# Strip the frames from the source video.
ffmpeg -i "$1" "frames/$filename/%06d.bmp"

# Cound the frames in the folder.
totalFrames=$(ls ./frames/"$filename"/*.bmp | wc -l)

# Get the size of the image.
size=$(identify -format "%[fx:w]x%[fx:h]" ./frames/"$filename"/000001.bmp)


## === Doing the processing ===
i=1
t=0
for f in "./frames/$filename/"*.bmp; do
   # Calculate how much scaling we do based on how far through the frames we are.
   let "scale=512 - ($i * 340 / $totalFrames)"

   # Make a filename to dump the new frame into.
   frame_name=./frames/"$filename"/liquid/$(printf %06d $i).bmp

   # The magick (ha get it) happens here. We run it in the background too.
   convert-im6 "$f" -liquid-rescale "$scale"x"$scale" -resize $size\! "$frame_name" &

   # Increment our frame "I"ncrement and "C"oncurrent processes counter.
   ((i++))
   ((c++))

   # When our concurrent processes exceeds our limit, wait until the finish and
   # reset our counter. 
   if (( $c > $maxProcesses )); then
	echo "Processing batch $i/$totalFrames"
   	wait
   	c=0
   fi
done

# Hold up, wait a minute.
# Wait for any background processes to finish before we re combine the frames.
wait


# Convert the images into a video again and merge the audio from the source back in.
ffmpeg -framerate "$fps" -thread_queue_size 1024 -i ./frames/"$filename"/liquid/%06d.bmp -thread_queue_size 1024 -i "$1" -c:v libx264 -preset slow -crf 23 -pix_fmt yuv420p -map "0:v:0" -map "1:a:0?" -y "./liquid_$filename.mp4"

# Delete all the left over junk.
rm -rf ./frames/"$filename"