Automation

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I needed a quick way of converting videos to gifs on Linux -ffmpeg and this post on stackexchange to the rescue!

The result is this neat little bash script:

#!/bin/bash

if [[ $# -eq 0 ]] ; then
 echo "Usage: videoToGif inputFile [outputFile] [FPS] [WIDTH]"
 echo "Example: videoToGif inputFile.ext outputFile.gif 60 360"
 exit 0
fi

inputFile=$1
outputFile=${2:-output.gif}

FPS=${3:-30}
WIDTH=${4:-360}

#Generate palette for better quality
ffmpeg -i $inputFile -vf fps=$FPS,scale=$WIDTH:-1:flags=lanczos,palettegen tmp_palette.png

#Generate gif using palette
ffmpeg -i $inputFile -i tmp_palette.png -loop 0 -filter_complex "fps=$FPS,scale=$WIDTH:-1:flags=lanczos[x];[x][1:v]paletteuse" $outputFile

rm tmp_palette.png

I used it to convert a Screencast created with "recordMyDesktop" (from OGV format) to a GIF.

• 2 Comments

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One of the tasks I come across often is converting images from one format into another. For instance, I need to convert SVG to PNG.

This can be achieved easily by using the "convert" commandline tool (ImageMagick) and a standard for loop in linux (note that I wrote the *.svg statement in the for command on purpose and that I use "$f" on purpose):

for f in *.svg ; do
    convert "$f" "$f.png"
done

However, this produces ugly file names like "file1.svg.png", which could be desireable in some scenarios, but not in my case when I deploy it for a website. You can bypass this by using ${f%svg}png:

for f in *.svg ; do
    convert "$f" "${f%svg}png"
done

Essentially this tool can handle a lot of use cases, for instance you can specify the picture density and which color should be used as transparent:

for f in *.svg ; do
    convert "$f" -density 300 -transparent white "${f%svg}png"
done

If you only want your pictures to have a certain size, you can resize them, e.g. using -resize 64x64:

for f in *.svg ; do
    convert "$f" -resize 64x64 -density 300 -transparent white "${f%svg}png"
done

However, you need to be careful when doing this. For instance, when the source image is smaller than the destination image, you might run into problems, and need to use the command like this:

for f in *.svg ; do
    convert  -resize 64x64 -density 300  "$f" -resize 64x64 -density 300 -transparent white "${f%svg}png"
done