Fragment shader

fragment-shader.c

precision highp float;

uniform sampler2D u_image;
uniform sampler2D u_image_frame;
uniform vec2 u_resolution;
varying vec2 v_texCoord;

void main() {
  float x_offset = mod( gl_FragCoord.y ,2.0  ) < 1.0 ? 0.5 : 0.0 ;
  vec4 y4 =  texture2D(u_image_frame, vec2 ( v_texCoord.x / 1.0  , v_texCoord.y / 1.5  )   )  ;
  vec4 u4 = (texture2D(u_image_frame, vec2 ( x_offset + v_texCoord.x  / 2.0  ,2.0/3.0 +  v_texCoord.y / 6.0  )   ) -0.50 ) * 2.0 ;
  vec4 v4 = (texture2D(u_image_frame, vec2 ( x_offset + v_texCoord.x / 2.0  , 5.0/6.0 + v_texCoord.y / 6.0  )   ) -0.50 ) * 2.0 ;   
  
  float y = y4[0] ;
  float u = u4[0] ;
  float v = v4[0] ;   

  float R = clamp(y + 1.13 * v, 0.0, 1.0) ;
  float G = clamp(y - 0.39 * u - 0.58 * v, 0.0, 1.0) ;
  float B = clamp(y + 2.03 * u, 0.0, 1.0) ;

  vec4 video_pixel = vec4( vec3(R,G,B), 1.0) ;
  gl_FragColor =  G > (R+B) ?  texture2D(u_image, v_texCoord) : video_pixel  ;
}