custom_nodes/ComfyUI-VideoHelperSuite/video_formats/gifski.json

{
    "main_pass":
    [
        "-n",
        "-pix_fmt", "yuv420p",
        "-crf", "20",
        "-b:v", "0"
    ],
    "extension": "webm",
    "gifski_pass": [
        "-Q", ["quality","INT", {"default": 90, "min": 1, "max": 100, "step": 1}]
    ]
}