diff --git a/gopro_8:7/compute_gopro_8:7.py b/gopro_8:7/compute_gopro_8:7.py
index 16f11c2..3668249 100644
--- a/gopro_8:7/compute_gopro_8:7.py
+++ b/gopro_8:7/compute_gopro_8:7.py
@@ -9,6 +9,7 @@ import math
 
 frame_width = 8
 frame_height = 7
+input_ratio = frame_width / frame_height
 
 input_vertical_fov = 108.0
 input_diagonal_fov = 156.0
@@ -20,14 +21,14 @@ output_horizontal_length = math.sqrt((input_diagonal_length ** 2) / (input_verti
 output_diagonal_length = math.hypot(output_horizontal_length, input_vertical_length)
 output_diagonal_fov = math.degrees(math.atan(output_diagonal_length)) * 2.0
 
-output_ratio = output_horizontal_length / input_vertical_length
+output_ratio = 1.0 / (output_horizontal_length / input_vertical_length)
 
 print("Output FOV   = %f" % output_diagonal_fov)
 print("Output Ratio = %f" % output_ratio)
 print("= Resolutions =====================")
 
 def width_rounded_8(height):
-    width = int(round(height * output_ratio))
+    width = int(round(height * input_ratio))
     return ((width + 4) // 8) * 8
 
 print("QHD            = %i x 540" % width_rounded_8(540))
diff --git a/gopro_8:7/preset_gopro_8:7_4K_2160p.py b/gopro_8:7/preset_gopro_8:7_4K_2160p.py
index 48d5572..c2b1b96 100644
--- a/gopro_8:7/preset_gopro_8:7_4K_2160p.py
+++ b/gopro_8:7/preset_gopro_8:7_4K_2160p.py
@@ -91,7 +91,7 @@ adm.addVideoFilter(
     "shaderFile=/opt/rk/avidemux/unfish_gopro_8:7.glsl")
 adm.addVideoFilter(
     "swscale",
-    "width=3312",
+    "width=2472",
     "height=2160",
     "algo=1",
     "sourceAR=0",
diff --git a/gopro_8:7/preset_gopro_8:7_FullHD_1080p.py b/gopro_8:7/preset_gopro_8:7_FullHD_1080p.py
index 3d9302c..7fb9900 100644
--- a/gopro_8:7/preset_gopro_8:7_FullHD_1080p.py
+++ b/gopro_8:7/preset_gopro_8:7_FullHD_1080p.py
@@ -91,7 +91,7 @@ adm.addVideoFilter(
     "shaderFile=/opt/rk/avidemux/unfish_gopro_8:7.glsl")
 adm.addVideoFilter(
     "swscale",
-    "width=1656",
+    "width=1232",
     "height=1080",
     "algo=1",
     "sourceAR=0",
diff --git a/gopro_8:7/preset_gopro_8:7_HD_720p.py b/gopro_8:7/preset_gopro_8:7_HD_720p.py
index 4ab2b10..7482c78 100644
--- a/gopro_8:7/preset_gopro_8:7_HD_720p.py
+++ b/gopro_8:7/preset_gopro_8:7_HD_720p.py
@@ -91,7 +91,7 @@ adm.addVideoFilter(
     "shaderFile=/opt/rk/avidemux/unfish_gopro_8:7.glsl")
 adm.addVideoFilter(
     "swscale",
-    "width=1104",
+    "width=824",
     "height=720",
     "algo=1",
     "sourceAR=0",
diff --git a/gopro_8:7/preset_gopro_8:7_QHD_540p.py b/gopro_8:7/preset_gopro_8:7_QHD_540p.py
index c650acf..262600d 100644
--- a/gopro_8:7/preset_gopro_8:7_QHD_540p.py
+++ b/gopro_8:7/preset_gopro_8:7_QHD_540p.py
@@ -91,7 +91,7 @@ adm.addVideoFilter(
     "shaderFile=/opt/rk/avidemux/unfish_gopro_8:7.glsl")
 adm.addVideoFilter(
     "swscale",
-    "width=832",
+    "width=616",
     "height=540",
     "algo=1",
     "sourceAR=0",
diff --git a/gopro_8:7/unfish_gopro_8:7.glsl b/gopro_8:7/unfish_gopro_8:7.glsl
index cfe28a6..e683006 100644
--- a/gopro_8:7/unfish_gopro_8:7.glsl
+++ b/gopro_8:7/unfish_gopro_8:7.glsl
@@ -13,17 +13,19 @@ uniform float pts;
 
 const vec2 half_pixel = vec2(0.5, 0.5);
 
+const vec2 input_scale = vec2(0.652485, 1.0);
 const float input_fov = 156.0;
 const float output_fov = 119.789529;
 
 vec2 unfish(vec2 coord) {
     float diameter = sqrt(dot(myResolution, myResolution));
     vec2 center = myResolution * 0.5;
-    vec2 position = coord - center;
-    float input_distance = length(position);
-    float input_foc = diameter / radians(input_fov);
-    float output_foc = diameter / (2.0 * tan(radians(output_fov) * 0.5));
-    return center + position * (input_foc * atan(input_distance / output_foc) / input_distance);
+    vec2 input_position = (coord - center) * input_scale;
+    float input_distance = length(input_position);
+    float input_len = diameter / radians(input_fov);
+    float output_len = diameter / (2.0 * tan(radians(output_fov) * 0.5));
+    float unfish_ratio = input_len * atan(input_distance / output_len) / input_distance;
+    return center + input_position * unfish_ratio;
 }
 
 void main() {