vibrance shader glsl

[geextahslex]

Hi I use this shader to desaturate dark colors in mpv. I want to make something similar but with vibrance instead of saturation. Can you help me out with that? Thank you :)

//!PARAM Strength
//!DESC Desat Strength
//!TYPE float
//!MINIMUM 0
//!MAXIMUM 1
1

//!HOOK MAIN
//!BIND HOOKED
//!DESC Desaturation smooth

#define Thresh 35/255.
#define w 10/255.
#define CoefLuma vec4(0.2126, 0.7152, 0.0722, 0) //sRGB, HDTV

/* simple threshold with mpv glsl
Strength*desaturation [0 to1.0], 0: full color, 1: grayscale.
*/

vec4 hook()  {
   vec4 c0 = HOOKED_texOff(0);
   float desaturation = smoothstep(Thresh + w, Thresh - w, dot(c0, CoefLuma));
   // return vec4(desaturation, 1);
   c0.rgb = mix(c0.rgb, vec3(dot(c0, CoefLuma)), Strength*desaturation);

   return c0;
}