Fixing Vapoursynth-rife-ncnn-vulkan Build Failure

Nov 29, 2025 by Admin 50 views

Encountering build failures with vapoursynth-rife-ncnn-vulkan can be frustrating, especially when you're trying to optimize your video processing workflows. This article dives into a specific build failure scenario, its root cause, and a practical solution. We'll also touch on some additional considerations for maintaining a smooth build process. Let's get started, guys!

Understanding the Build Failure

The core issue revolves around a compilation error during the emerge process for media-plugins/vapoursynth-rife-ncnn-vulkan. The error message, ‘const class ncnn::Option’ has no member named ‘use_shader_pack8’, clearly indicates an incompatibility between the vapoursynth-rife-ncnn-vulkan plugin and a newer version of the ncnn library. This often happens when APIs change between library versions, and the plugin hasn't been updated to accommodate those changes.

Diving Deep into the Error Log

To better understand the issue, let's break down the relevant parts of the provided emerge log:

Emerge Process: The log shows the system attempting to emerge (install) media-plugins/vapoursynth-rife-ncnn-vulkan-9_p30.
Source Unpacking and Preparation: The source code is successfully unpacked and prepared for compilation.
Configuration: Meson, a build system generator, is used to configure the build. It finds dependencies like OpenMP, threads, Vulkan, and VapourSynth. It also finds ncnn, but issues a warning about missing glslang dependencies for ncnn.
Compilation Failure: The compilation process fails with the error message related to ncnn::Option not having the use_shader_pack8 member. This is a critical error that stops the build.

The error occurs in the RIFE/warp.cpp file, specifically within the Warp::create_pipeline function. The code attempts to access opt.use_shader_pack8, but this member doesn't exist in the version of ncnn being used during the build.

Why Did This Happen?

The root cause is a breaking change in the ncnn library. Newer versions of ncnn might have removed or renamed the use_shader_pack8 member in the ncnn::Option class. The vapoursynth-rife-ncnn-vulkan plugin, which was likely developed against an older ncnn version, is now incompatible with the newer ncnn API.

The Solution: Downgrading ncnn

The suggested solution is to downgrade the dev-libs/ncnn package to version 20250503. This version is known to be compatible with the current vapoursynth-rife-ncnn-vulkan plugin. Here’s how you can do it:

Identify Available Versions: Use the eix -e ncnn command to list available versions of the ncnn package. This command provides information about installed and available versions, along with their use flags.
Downgrade the Package: Use Gentoo's package manager, Portage, to downgrade ncnn to the known working version. This can typically be done using the emerge command with a specific version number:
```
sudo emerge =dev-libs/ncnn-20250503
```
Note: Make sure to include the = sign to specify the exact version. You might also need to unmask the specific version if it's not already available in your accepted keywords.
Re-emerge vapoursynth-rife-ncnn-vulkan: After successfully downgrading ncnn, re-attempt the emerge command for vapoursynth-rife-ncnn-vulkan:
```
sudo emerge media-plugins/vapoursynth-rife-ncnn-vulkan
```
This should now proceed without the compilation error, as the ncnn library and the plugin are now compatible.

Additional Considerations

Keyword Setting in Live Ebuilds

The suggestion to explicitly set KEYWORD=”” in the media-plugins/vapoursynth-rife-ncnn-vulkan live ebuild is important for stability and control over your system. Here’s why:

Live Ebuilds and Rolling Releases: Live ebuilds (those with a -9999 or similar suffix) track the latest changes from a project's source repository. This means they are constantly updated, potentially introducing new dependencies or incompatibilities.
Keyword Control: In Gentoo, keywords specify which architectures and stability levels a package is considered suitable for. By default, live ebuilds might inherit unstable keywords (like ~amd64), meaning they'll pull in the latest, potentially untested, versions of dependencies.
Setting KEYWORD=””: Setting KEYWORD=”” tells Portage to only install this package if all its dependencies are satisfied by stable packages. This can prevent unexpected breakage caused by pulling in bleeding-edge versions of libraries like ncnn.

To set KEYWORD=”” for the vapoursynth-rife-ncnn-vulkan live ebuild, you can add the following line to /etc/portage/package.keywords/:

=media-plugins/vapoursynth-rife-ncnn-vulkan-9999

Reporting the Issue

It's crucial to report this incompatibility issue to both the vapoursynth-rife-ncnn-vulkan and ncnn developers. This helps them understand the impact of API changes and encourages them to provide better compatibility or clearer upgrade paths in the future. Include detailed information about the error, the ncnn versions involved, and your system configuration.

Understanding the CMake Warnings

The build log also includes CMake warnings:

WARNING: CMake: Dependency glslang::glslang for ncnn was not found
WARNING: CMake: Dependency glslang::SPIRV for ncnn was not found

These warnings indicate that the glslang and SPIRV libraries, which are related to shader compilation, were not found during the ncnn build process. While the build might still succeed without them, these libraries are often required for optimal performance and full functionality, especially when using Vulkan for GPU acceleration. Consider installing these libraries to ensure ncnn is built with all its optional dependencies.

On Gentoo, you can typically install them using Portage:

sudo emerge dev-util/glslang

Verifying the Solution

After downgrading ncnn and re-emerging vapoursynth-rife-ncnn-vulkan, it’s important to verify that the plugin is working correctly. You can do this by:

Loading the Plugin in VapourSynth: Create a simple VapourSynth script that uses the rife function and check if it loads without errors.
Running a Test Script: Run a test script that performs some basic video processing using the rife function and verify that the output is as expected.
Checking for GPU Usage: Monitor your GPU usage while running the test script to ensure that the plugin is utilizing the GPU for acceleration.

Conclusion

Build failures are a common part of software development and usage, especially when dealing with complex systems like VapourSynth and its plugins. By understanding the error messages, analyzing the build logs, and applying appropriate solutions like downgrading packages, you can often resolve these issues and get back to your video processing tasks. Remember to report any incompatibilities you find to the relevant developers to help improve the overall ecosystem. Keep tweaking, keep testing, and happy video enhancing, folks!