avconv -i "$inputFile" -threads 8 -s 1280x720 -preset libvpx-720p -b 3900k -pass 1 -an -f webm -y "$outputFile"
avconv -i "$inputFile" -threads 8 -preset libvpx-720p -pass 2 -b 3900k -acodec libvorbis -ar 44100 -ac 2 -ab 128k -f webm -y "$outputFile"