Converts mp3 files to opus concurrently (one conversion per core)

mp3_to_opus.sh

#!/bin/bash

# Author : <Ivan Zderadicka> ivan@zderadicka.eu
# License: MIT
VERSION=0.1.1
BITRATE=48
CUTOFF=20000
APPLICATION=audio
FORMAT=opus
QUALITY=10

trap "exit 2" SIGINT

print_help () {
    cat <<EOF
Converts audio files to opus encoding

Usage: $0 [options] <directory>...

-h, --help              prints help and exits
-v,--version            prints version and exits
-d, --delete            deletes input file after conversion
-r, --recursive         converts recursiverly in subdirectories
-b <bitrate>,
--bitrate <bitrate>     bitrate in kilobits  eg. 24, 32, 48, 64, 96 ... [default: 48]
-c <feq>,
--cutoff <freq>         cutoff frequency for low-pass filter [default: 20000]
                        recommended values: 4000, 6000, 8000, 12000, or 20000
-a <app>,
--app <app>             application type - voip, audio or lowdelay 
-f <format>,
--format <format>       output container format - opus, mka, webm [default: opus]  
-q <quality>,
--quality <quality>     encoding quality 0 fast, low quality - 10 slow, high quality
                        [default: 10]






EOF
}

while (( $# > 0 ))
do
    case $1 in
        -b|--bitrate) # bitrate in kilobits  eg. 24, 32. 64 ...
        BITRATE="$2"
        shift
        ;;
        -c|--cutoff) # cutoff - for low pass filter -  4000, 6000, 8000, 12000, or 20000
        CUTOFF="$2"
        shift
        ;;
        -a|--app) # application type - voip, audio or lowdelay
        APPLICATION="$2"
        shift
        ;;
        -f|--format) # container format ogg, mkv, webm ...
        FORMAT="$2"
        shift 
        ;;
        -q|--quality) # compression quality - 0 fast, low quality - 10 - low high quality 
        QUALITY="$2"
        shift 
        ;;
        -d|--delete) # delete input file after conversion
        DELETE=YES
        ;;
        -r|--recursive) # resurse into sub directories
        RECURSIVE=" "
        ;;
        -h|--help)
            print_help
            exit
            ;;
        -v|--version)
            echo Version: $VERSION
            exit
            ;;
        -*=*)
            echo Do not support options with =
            exit 1
            ;;
        *)
           break     # unknown option, possibly argument
            ;;
    esac
    shift
done

wait_proc() {
	while (( $(jobs -pr | wc -l ) >= $(nproc) )); do
		sleep 1
	done
}

while (( $# > 0 )); do

    if [[ -n "$1" && -d "$1" ]]; then
        
        while read -d $'\0' FILE ; do

                echo "Processing $FILE"
                { 
                 ffmpeg -nostdin -v error -i "$FILE" -y -map_metadata 0 -map a -vn -acodec libopus -b:a ${BITRATE}k -vbr on -compression_level $QUALITY -application $APPLICATION -cutoff $CUTOFF "${FILE%.*}.$FORMAT"
                
                if [[ $? -ne 0 ]]; then
                    echo "Encoding error on $FILE ret code $?" >&2
                else 
                    echo "Finished $FILE"
                    if [[ -n $DELETE ]]; then
                        rm "$FILE"
                    fi
                fi
                
                } &
                wait_proc
        done < <(find "$1" -depth ${RECURSIVE:--maxdepth 1} -type f -name "*.mp3" -print0 | sort -z)
    else
        echo "$1 is not directory" >&2
    fi
    shift 
done
wait
exit 0