Add gif2webm script

gif2webm converts gifs to webm using ffmpeg

gif2webm

@@ -0,0 +1,20 @@
+#!/bin/bash
+
+if [[ -n "${1}" && -n "${2}" ]]; then
+
+	filters="fps=15"
+
+	if [[ -n "${3}" ]]; then
+		filters+=",scale=${3}:flags=lanczos"
+	fi
+
+
+ffmpeg -i "$1" -c:v libvpx-vp9 -vf "$filters" -pass 1 -b:v 0 -crf 33 -threads 8 -speed 2 -tile-columns 6 -frame-parallel 1 -auto-alt-ref 1 -lag-in-frames 25 -f webm -y /dev/null
+
+ffmpeg -i "$1" -c:v libvpx-vp9 -vf "$filters" -pass 2 -b:v 0 -crf 33 -threads 8 -speed 2 -tile-columns 6 -frame-parallel 1 -auto-alt-ref 1 -lag-in-frames 25 -f webm "$2"
+
+exit;
+
+fi
+
+echo -e "Usage: ${0} <input-file> <output-file> <height:-1 or -1:width>"