GLSL code for converting between RGB and YCbCr (DIVA Edition)

conv.glsl

void mainImage( out vec4 fragColor, in vec2 fragCoord )
{
    // Normalized pixel coordinates (from 0 to 1)
    vec2 uv = fragCoord/iResolution.xy;

    vec4 col = texture(iChannel2, uv);
    vec2 mip1 = texture(iChannel0, uv).xy;
    vec2 mip2 = texture(iChannel1, uv).xy;
    
    mat3 yMat = mat3(1.,     0., 1.5748,
                     1., -.1873, -.4681,
                     1., 1.8556, 0.);
    
    mat3 rMat = mat3(.2126, .7152, .0722,
                    -.1146,-.3854, .5,
                        .5,-.4542,-.0458);
    
    //YCbCr 2 RGB
    vec3 final = vec3(mip1.g, mip2.r-.5, mip2.g-.5) * yMat;
    final = final.zyx;
    //RGB 2 YCbCr
    vec3 final2 = col.zyx * rMat;
    final2.gb += .5;
    
    //Outputs
    vec2 alum = vec2(col.a, final2.r);
    vec2 cbr = vec2(final2.g, final2.b);
    
    
    fragColor.xyz = vec4(alum, 1,1.0).xyz;
}