Commands by pingiun (1)

  • Count the total amount of hours of your music collection

    First the find command finds all files in your current directory (.). This is piped to xargs to be able to run the next shell pipeline in parallel. The xargs -P argument specifies how many processes you want to run in parallel, you can set this higher than your core count as the duration reading is mainly IO bound. The -print0 and -0 arguments of find and xargs respectively are used to easily handle files with spaces or other special characters. A subshell is executed by xargs to have a shell pipeline for each file that is found by find. This pipeline extracts the duration and converts it to a format easily parsed by awk. ffmpeg reads the file and prints a lot of information about it, grep extracts the duration line. cut and sed cut out the time information, and tr converts the last . to a : to make it easier to split by awk. awk is a specialized programming language for use in shell scripts. Here we use it to split the time elements in 4 variables and add them up. Show Sample Output


    1
    find . -print0 | xargs -0 -P 40 -n 1 sh -c 'ffmpeg -i "$1" 2>&1 | grep "Duration:" | cut -d " " -f 4 | sed "s/.$//" | tr "." ":"' - | awk -F ':' '{ sum1+=$1; sum2+=$2; sum3+=$3; sum4+=$4 } END { printf "%.0f:%.0f:%.0f.%.0f\n", sum1, sum2, sum3, sum4 }'
    pingiun · 2019-03-01 20:21:48 44

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