ffmpeg -h encoder=libwebp_anim

libwebp_anim.txt

Encoder libwebp_anim [libwebp WebP image]:
    General capabilities: delay
    Threading capabilities: none
    Supported pixel formats: bgra yuv420p yuva420p
libwebp_anim AVOptions:
  -lossless          <int>        E..V...... Use lossless mode (from 0 to 1) (default 0)
  -preset            <int>        E..V...... Configuration preset (from -1 to 5) (default none)
     none            -1           E..V...... do not use a preset
     default         0            E..V...... default preset
     picture         1            E..V...... digital picture, like portrait, inner shot
     photo           2            E..V...... outdoor photograph, with natural lighting
     drawing         3            E..V...... hand or line drawing, with high-contrast details
     icon            4            E..V...... small-sized colorful images
     text            5            E..V...... text-like
  -cr_threshold      <int>        E..V...... Conditional replenishment threshold (from 0 to INT_MAX) (default 0)
  -cr_size           <int>        E..V...... Conditional replenishment block size (from 0 to 256) (default 16)
  -quality           <float>      E..V...... Quality (from 0 to 100) (default 75)