Jpegloop
Counting up
for ((i=1;i<=100;i++))
do
echo $i
done
Counting down
for ((i=1;i<=100;i++))
do
echo $i
done
Doing something
for ((i=1;i<=10;i++))
do
convert original.jpg -quality $i output$i.jpg
done
Fixing the filenames (zero padding with printf)
printf can be used to "zero-pad" a number (ie make a good filename from a counting number)
printf "%03d" 7
means "zero-pad" (add zeros) to always be 3 characters long, and outputs:
007
command substitution
$() means "command substitution" -- or do what's inside the parentheses and then substitute the result. This can be used to store the result of running printf in a variable (to then use again)
for ((i=1;i<=10;i++))
do
name=$(printf "%03d\n" $i)
convert original.jpg -quality $i output$name.jpg
done
Compressing the "lastframe" to perform an iterative compression
The trick here is to keep a "lastframe" copy that can always be used as the input to the convert command.
cp $j lastframe.jpg
for ((i=100;i>=1;i--))
do
name=$(printf "%03d\n" $((100-i)))
convert lastframe.jpg -quality $i output$name.jpg
cp output$name.jpg lastframe.jpg
done
ffmpeg -f image2 -i output%03d.jpg -r 10 $j.mp4
Converting the images to a movie
ffmpeg -f image2 -i output%03d.jpg -r 10 output.mp4
Apply to a directory of files
The whole thing can be wrapped in a "for" loop to process a whole bunch of input images at once.
#!/bin/bash
for j
do
cp $j lastframe.jpg
for ((i=100;i>=1;i--))
do
name=$(printf "%03d\n" $((100-i)))
convert lastframe.jpg -quality $i output$name.jpg
# COPY THE CURRENT TO "lastframe.jpg"
cp output$name.jpg lastframe.jpg
done
ffmpeg -f image2 -i output%03d.jpg -r 10 $j.mp4
done