cuts a clip from a non-standard .mov file recorded by GoToMeeting

gtm-cut.sh

#!/bin/bash

function print_usage() {
	cat <<EOF
Usage: `basename "$0"` --start time --length seconds --in path --out path

    --start time:     start time in 'HH:MM:SS.mmm' format
    --length seconds: clip length in integer seconds
    --in path:        input file, must have '.mov' extension
    --out path:       output file, must have '.mov' extension
    --help:           prints this usage statement

Cuts a clip from a .mov file recorded by GoToMeeting.

GTM creates recordings that, by default, are not capable of being properly
parsed and rendered by ffmpeg, vlc, and other free tools. This script sets up
the flags necessary for cutting these files, though the output is NOT any more
portable than the GTM-created input files.
EOF
}

function is_valid_timecode() {
	[[ "$1" =~ ([0-9]{2}:){2}[0-9]{2}\.[0-9]{1,3} ]]
}

function is_integer() {
	[ "$1" -eq "$1" ] 2> /dev/null
}

function ext_is_mov() {
	[ "${1: -4}" == ".mov" ]
}

while (( "$#" )); do
	case "$1" in
		'--length')
			length="$2"
			shift
			;;
		'--start')
			starttime="$2"
			shift
			;;
		'--in')
			infile="$2"
			shift
			;;
		'--out')
			outfile="$2"
			shift
			;;
		'-h'|'--help'|'-u'|'--usage'|*)
			print_usage
			exit 0
			;;
	esac
	shift
done

if ! is_valid_timecode "$starttime"; then
	printf "Error: Invalid start: %s\n" "$starttime" >&2
	print_usage
	exit 1
fi

if ! is_integer "$length"; then
	printf "Error: Invalid length: %s\n" "$length" >&2
	print_usage
	exit 1
fi

if ! ext_is_mov "$infile" || [[ ! -f "$infile" ]]; then
	printf "Error: Invalid or missing in: '%s'\n" "$infile" >&2
	print_usage
	exit 1
fi

if ! ext_is_mov "$outfile" || [[ -z "$outfile" ]]; then
	printf "Error: Invalid or missing out: '%s'\n" "$outfile" >&2
	print_usage
	exit 1
fi

# http://stackoverflow.com/questions/22674924/problems-transcoding-gotomeeting-output-using-ffmpeg
ffmpeg -fflags +genpts+igndts \
	-i "$infile" \
	-ss "$starttime" -t "$length" \
	-c:v libx264 -preset slow -level 30 -qmin 38 -qmax 55 \
	-movflags faststart -r:v 10 -vsync 2 -async 1 -map 0:v,0:a -map 0:a \
	"$outfile"