#! /bin/zsh
#
# this file:
#   https://dataswamp.org/~incal/conf/.zsh/video-slice

     ###################
    ## slice and dice ##
    ## video stuff :) ##
    ###################

video-part () {
    local beg=$1
    local end=$2
    local src=$3
    local dst=${4:-${src:r}-part.${src:e}}

    ffmpeg \
      -y   \
      -v quiet \
      -i $src  \
      -ss $beg \
      -to $end \
      -c copy  \
               $dst
}

# https://unix.stackexchange.com/a/212518
split-video () {
    local fs=($@)

    local s=1

    local f
    local src
    local name
    local ext
    for f in $fs; do
        src=$f
        name=${src:r}
        ext=${src:e}

        ffmpeg \
            -i $src \
            -c copy \
            -map 0  \
            -segment_time 00:00:${s} \
            -f segment               \
            -reset_timestamps 1      \
                                     ${name}-%03d.${ext}
    done
}

# https://video.stackexchange.com/questions/4563/how-can-i-crop-a-video-with-ffmpeg
video-crop () {
    local x=$1
    local y=$2
    local w=$3
    local h=$4

    local src=$5
    local name=${src:r}
    local ext=${src:e}
    local dst=${name}-crop.${ext}

    ffmpeg \
        -y                                   \
        -i $src                              \
        -filter:v "crop=${w}:${h}:${x}:${y}" \
        -c:a copy                            \
                                             $dst
}

video-remove-border () {
    local border=$1
    local src=$2

    local x_border=$(( 2 * $border ))
    local y_border=$x_border

    local name=${src:r}
    local ext=${src:e}
    local dst=${name}-no-border.${ext}

    ffmpeg \
        -y                                           \
        -i $src                                      \
        -vf "crop=in_w-${x_border}:in_h-${y_border}" \
        -c:a copy                                    \
                                                     $dst
}

video-add-border () {
    local src=$1
    local w=${2:-1080}
    local h=${3:-1920}

    local name=${src:r}
    local ext=${src:e}
    local dst=${name}-border.${ext}

    local ar="${w}:${h}"

    ffmpeg \
        -y      \
        -i $src \
        -vf "scale=${ar}:force_original_aspect_ratio=decrease,pad=${ar}:(ow-iw)/2:(oh-ih)/2,setsar=1" \
        $dst
}

video-merge () {
    local src1=$1
    local src2=$2

    local name=${src1:r}-${src2:r}
    local ext=${src1:e}

    local dst=${name}.${ext}

    local list_file=both.txt

    echo "file $src1" >  $list_file
    echo "file $src2" >> $list_file

    ffmpeg \
        -y            \
        -f concat     \
        -safe 0       \
        -i $list_file \
        -c copy       $dst
}

slice-video () {
    # usage:
    # slice-video FILE [BEG_SEC=-2] LEN_SEC

    local src=$1
    local name=${src:r}
    local ext=${src:e}
    local dst=${name}-sliced.${ext}

    local beg
    local len
    case $# in
        (2) beg=-2
            len=$2 ;;
        (3) beg=$2
            len=$3 ;;
        (*) wrong-number-of-arguments-message $(( $# - 1 )) "1 or 2"
            return ;;
    esac

    ffmpeg \
        -y         \
        -v   quiet \
        -i   $src  \
        -ss  $beg  \
        -t   $len  \
        -c:a copy  \
        -c:v copy  \
                   $dst
    len $dst
}

video-drop-after () {
    local after=$1
    local f=$2

    slice-video $f $after
}