Trim videos losslessly with ffmpeg

trim.sh

alias trim=trim

function trim() {
    if [ "$#" != "3" ]; then
        echo "Please provide all 3 arguments: 'filename start duration'"
        return 1
    fi
    video="${1}"
    filename="${1%.*}"
    extension="${1##*.}"
    start="${2}"
    duration="${3}"
    if [ ! -f "${video}" ]
    then
        echo "$0: File '${video}' not found."
    fi
    case ${start} in
        ''|*[!0-9]*)
            echo "start has to be a number"
            return 1
            ;;
        *)
    esac
    case ${duration} in
        ''|*[!0-9]*)
            echo "duration has to be a number"
            return 1
            ;;
        *)
    esac
    end=$(echo ${start} + ${duration} | bc)
    output="${filename}-trimmed-from-${start}s-to-${end}s.${extension}"
    echo "Trimming video from ${start}s till ${end}s..."
    ffmpeg -nostdin -hide_banner -loglevel quiet -ss ${start} -t ${duration} -i "${video}" -c copy "${output}"
    echo "Trimmed video saved as ${output}"
}