FFMPEG: Convert to GIF.sh

to_gif.sh

#!/bin/bash

cnv_to_gif() {
    local usage="Usage: $0 [--fps <fps>] [--wsize <width>] [--hsize <height>] [--start <timestamp>] [--end <timestamp>] <input> [<output>]"

    local in_f="" out_f="" fps=15 wsize="500" hsize="-1" start="00:00:00" end="00:00:00"
    while [[ $# -gt 0 ]]; do
        case "$1" in
            --fps) fps="$2"; shift 2;;
            --wsize) wsize="$2"; shift 2;;
            --hsize) hsize="$2"; shift 2;;
            --start) start="$2"; shift 2;;
            --end) end="$2"; shift 2;;
            -h|--help)
                echo "$usage"; exit 0
                ;;
            *)
                if [[ -z "$in_f" ]]; then
                    in_f="$1"
                elif [[ -z "$out_f" ]]; then
                    out_f="$1"
                fi
                shift
                ;;
        esac
    done

    if [[ -z $out_f ]]; then
        out_f="${in_f}.gif"
    fi

    echo "| IN     |: $in_f"
    echo "| OUT    |: $out_f"
    echo "| PARAMS |: --fps=$fps / --wsize=$wsize / --hize=$hsize / --start=$start / --end=$end"
    read -p "Proceed with conversion? [y/N] " cnf
    if [[ "$cnf" != "y" && "$cnf" != "Y" ]]; then echo "Aborted"; exit 1; fi

    local trim_args=()
    if [[ "$start" != "00:00:00" ]]; then trim_args+=("-ss" "$start"); fi
    if [[ "$end" != "00:00:00" ]]; then trim_args+=("-to" "$end"); fi;

    # FILTER: pre-process, set fps, scale and split into 2 streams for pallette generation
    # FILTER: generate pallette for gif output (consumes s0)
    # FILTER: apply pallette to video stream (consumes s1 and pallette from p)
    ffmpeg -hide_banner "${trim_args[@]}" -i "${in_f}" -filter_complex "
        [in] $trim_filter fps=${fps}, scale=${wsize}:${hsize}:flags=lanczos [preproc];
        [preproc] split [s0][s1];
        [s0] palettegen= max_colors=256 : stats_mode=diff [p];
        [s1][p] paletteuse= dither=bayer : bayer_scale=5 : diff_mode=rectangle [out];

        [out]null
    " "${out_f}"
}

cnv_to_gif "$@"