avidemux_shaders/README.md

# Avidemux Shaders

Shaders for Avidemux with OpenGL support

## GoPro fisheye removal v2.0

![Sample image](https://blog.rozk.net/wp-content/uploads/2025/07/compare.png)

### gopro_8:7 - Fisheye removal for GoPro 11+, 8:7 ratio, 4K, HyperSmooth off

#### What's new

- New method based on sensor size and focal length
- Accurate frame widening
- Fisheye aware subsampling
- Rec.709 colorspace conversion

#### Content

- avidemux.patch  
Optional patch to use GL_NEAREST instead of GL_LINEAR for the luminance channel (the shader is implementing bilinear interpolation with colorspace conversion).

- unfish_gopro_8:7.py  
Script to compute the parameters

- unfish_gopro_8:7.glsl  
Shader for fisheye removal

- preset_gopro_8:7.py  
Preset for mp4, 4K, high quality compression

#### Installation for BSD/GNU-Linux systems:

- Copy the preset into ~/.avidemux6/custom or ~/.local/share/avidemux6/custom
- Copy the shader into /opt/rk/avidemux (or edit the preset to set the path)  

Or just run the script install_gopro_8:7.sh

_For commercial OS's, figure out the paths yourself, then edit the preset to fix the path to the .glsl file_

#### Usage:

- Load and edit video(s)
- Select "Custom/preset_gopro_8:7" in the menu
- Modify and/or add filters
- Save the video

#### Shader options

- #define color_conversion: comment out to disable gamma correction for the luminance channel
- #define texture_filtering: comment out to disable custom bilinear filtering for the luminance channel
- #define rotate_180: uncomment to rotate the image by 180 degrees