un-fisheye filter for gopro 8:7 ratio, wide fov, without hypersmooth

README.md

@@ -1,3 +1,6 @@
-# avidemux_shaders
+# Avidemux Shaders
 
-Shaders for avidemux
+Shaders for Avidemux with OpenGL support
+
+```unfish_gopro_8-7_wide_hypersmooth-off.glsl```
+Fisheye removal for GoPro, 8:7 aspect ratio, wide FOV, HyperSmooth off

unfish_gopro_8-7_wide_hypersmooth-off.glsl

@@ -0,0 +1,33 @@
+// Adapted from https://github.com/duducosmos/defisheye
+// (then resize to 1568x1080)
+
+#extension GL_ARB_texture_rectangle: enable
+
+uniform sampler2DRect myTextureY;
+uniform sampler2DRect myTextureU;
+uniform sampler2DRect myTextureV;
+uniform vec2 myResolution;
+uniform float pts;
+
+const vec2 half_pixel = vec2(0.5, 0.5);
+const float pi = 3.1415927;
+
+const float input_fov = 150.0 * pi / 720.0;
+const float output_fov = 116.0 * pi / 360.0;
+
+vec2 unfish(vec2 coord) {
+    vec2 center = myResolution * 0.5;
+    vec2 pos = coord - center;
+    float rd = length(pos);
+    float diameter = sqrt(dot(myResolution, myResolution));
+    return center + pos * ((diameter / (2.0 * sin(input_fov))) * sin(atan(rd / (diameter / (2.0 * tan(output_fov)))) * 0.5) / rd);
+}
+
+void main() {
+    vec2 y_coord = unfish(gl_TexCoord[0].xy + half_pixel);
+    vec2 uv_coord = y_coord * 0.5;
+    vec4 y = texture2DRect(myTextureY, y_coord);
+    vec4 u = texture2DRect(myTextureU, uv_coord);
+    vec4 v = texture2DRect(myTextureV, uv_coord);
+    gl_FragColor = vec4(y.r, u.r, v.r, 1.0);
+}