silentpcmrm

#!/bin/bash

# usage: silentpcmrm [-d] [-v] [-l] [-t THRESHOLD] INPUT

#	-d	debug mode: actions are listed but not carried out
#	-v	verbose mode: actions are carried out and listed
#	-l	list mode: files that will be deleted are listed, surrounded by single quotes. This allows the list to sent to `xargs` for example, to open in an audio editor to double check if there's anything worth keeping.
#	-n	no colours: don't use colours when printing to the screen
#	-t THRESHOLD	set the threshold below which a PCM file is considered silent
#	INPUT	list of files to check for silence

if ! command -v sox &> /dev/null; then
	echo "sox could not be found, and is required";
	exit;
fi
cols=$(tput cols)
threshold=0.0001;
while getopts ":dlnt:v" opt; do
	case $opt in
		d) debug=yes;;
		l) list=yes;;
		n) nocolours=yes;;
		t) threshold=$OPTARG;;
		v) verbose=yes;;
		\?) echo "Invalid option: -$OPTARG" >&2; exit 1;;
		:) echo "Option -$OPTARG needs an argument" >&2; exit 1;;
	esac
done
shift $(( OPTIND - 1 ))
if [ "${nocolours}" != 'yes' ]; then
	bold=$(tput bold);
	green=$(tput setaf 2);
	grey=$(tput dim)$(tput setaf 7);
	lblack=$(tput bold)$(tput setaf 0);
	lred=$(tput bold)$(tput setaf 1);
	red=$(tput setaf 1);
	reset=$(tput sgr0);
	white=$(tput setaf 7);
	yellow=$(tput setaf 3);
fi
# alert debug mode
if [ "${debug}" == 'yes' ]; then
	echo "${green}debug mode";
fi
# set print mode
if [[ "${verbose}" == 'yes' || "${debug}" == 'yes' ]]; then
	print=yes;
fi
# print threshold
if [ "${print}" == 'yes' ]; then
	echo "${green}using ${yellow}${threshold}${green} as threshold below which a file is considered 'silent'${reset}"; echo;
	padlimit=${cols};
	pad=$(printf '%*s' "$padlimit");
	pad=${pad// /.};
fi
for i in "${@}"; do
	# print file name
	if [ "${print}" == 'yes' ]; then
		printf '%s' "${i}";
	fi
	# check for zero length file
	if [ ! -s "${i}" ]; then
		if [ "${print}" = 'yes' ]; then
			echo "  ${yellow}${i}${reset} is ${blue}zero-length${reset}";
		fi
		if [ "${debug}" == 'yes' ]; then
			printf '%s\n' "  ${green}debug mode: ${red}remove ${bold}${white}${i}${reset} ";
		else
			if [ "${verbose}" == 'yes' ]; then
				printf '%s\n' "  ${red}Deleting ${bold}${white}${i}${reset} ";
			fi
			rm -f "${i}";
		fi
	else
		# read amplitude of file
		amplitude=$(sox "${i}" -n stat 2>&1 | grep "Maximum amplitude" | cut -d ":" -f 2 | sed 's/ //g');
		# check if amplitude is below threshold
		if [[ $(echo "if (${amplitude} > ${threshold}) 1 else 0" | bc) -eq 0 ]]; then
			# print amplitude
			if [ "${print}" == 'yes' ]; then
				amp="${reset}Max amplitude: ${red}${amplitude}${reset}";
				printf ' %*.*s %s\n' 0 $(( ${cols} - ${#i} - ${#amp} - 2 + ${#reset} * 5 )) "${lblack}${pad}${reset}" "${amp}";
			fi
			if [ "${debug}" == 'yes' ]; then
				# debug mode
				printf '%s' "  ${green}debug mode: ${red}remove ${bold}${white}${i}${reset} ";
				printf '%s\n' "[${yellow} $(du -h "${i}" | cut -f1) ${reset}]";
			elif [ "${list}" == 'yes' ]; then
				# list mode
				echo "'${i}'";
			else
				if [ "${verbose}" == 'yes' ]; then
					printf '%s' "  ${red}Deleting ${bold}${white}${i}${reset} ";
					printf '%s\n' "[${yellow} $(du -h "${i}" | cut -f1) ${reset}]";
					# echo "  ${red}Deleting ${bold}${white}${i}${reset}";
				fi
				rm -f "${i}";
			fi
		else
			# print amplitude
			if [ "${print}" == 'yes' ]; then
				amp="${reset}Max amplitude: ${green}${amplitude}${reset}";
				printf ' %*.*s %s\n' 0 $(( ${cols} - ${#i} - ${#amp} - 2 + ${#reset} * 5 )) "${lblack}${pad}${reset}" "${amp}";
			fi
		fi
	fi
done