Crate vapoursynth

Expand description

A safe wrapper for VapourSynth, written in Rust.

The primary goal is safety (that is, safe Rust code should not trigger undefined behavior), and secondary goals include performance and ease of use.

Functionality

Most of the VapourSynth API is covered. It’s possible to evaluate .vpy scripts, access their properties and output, retrieve frames; enumerate loaded plugins and invoke their functions as well as create VapourSynth filters.

For an example usage see examples/vspipe.rs, a complete reimplementation of VapourSynth’s vspipe in safe Rust utilizing this crate.

For a VapourSynth plugin example see sample-plugin which implements some simple filters.

Short example

use vapoursynth::prelude::*;

let env = Environment::from_file("test.vpy", EvalFlags::SetWorkingDir)?;
let node = env.get_output(0)?.0; // Without `.0` for VSScript API 3.0
let frame = node.get_frame(0)?;

println!("Resolution: {}×{}", frame.width(0), frame.height(0));

Plugins

To make a VapourSynth plugin, start by creating a new Rust library with crate-type = ["cdylib"]. Then add filters by implementing the plugins::Filter trait. Bind them to functions by implementing plugins::FilterFunction, which is much more easily done via the make_filter_function! macro. Finally, put export_vapoursynth_plugin! at the top level of src/lib.rs to export the functionality.

Important note: due to what seems to be a bug in rustc, it’s impossible to make plugins on the i686-pc-windows-gnu target (all other variations of x86_64 and i686 do work). Please use i686-pc-windows-msvc for an i686 Windows plugin.

Short plugin example

#[macro_use]
extern crate vapoursynth;

use anyhow::{anyhow, Error};
use vapoursynth::prelude::*;
use vapoursynth::core::CoreRef;
use vapoursynth::plugins::{Filter, FilterArgument, FrameContext, Metadata};
use vapoursynth::video_info::VideoInfo;

// A simple filter that passes the frames through unchanged.
struct Passthrough<'core> {
    source: Node<'core>,
}

impl<'core> Filter<'core> for Passthrough<'core> {
    fn video_info(&self, _api: API, _core: CoreRef<'core>) -> Vec<VideoInfo<'core>> {
        vec![self.source.info()]
    }

    fn get_frame_initial(
        &self,
        _api: API,
        _core: CoreRef<'core>,
        context: FrameContext,
        n: usize,
    ) -> Result<Option<FrameRef<'core>>, Error> {
        self.source.request_frame_filter(context, n);
        Ok(None)
    }

    fn get_frame(
        &self,
        _api: API,
        _core: CoreRef<'core>,
        context: FrameContext,
        n: usize,
    ) -> Result<FrameRef<'core>, Error> {
        self.source
            .get_frame_filter(context, n)
            .ok_or(anyhow!("Couldn't get the source frame"))
    }
}

make_filter_function! {
    PassthroughFunction, "Passthrough"

    fn create_passthrough<'core>(
        _api: API,
        _core: CoreRef<'core>,
        clip: Node<'core>,
    ) -> Result<Option<Box<dyn Filter<'core> + 'core>>, Error> {
        Ok(Some(Box::new(Passthrough { source: clip })))
    }
}

export_vapoursynth_plugin! {
    Metadata {
        identifier: "com.example.passthrough",
        namespace: "passthrough",
        name: "Example Plugin",
        read_only: true,
    },
    [PassthroughFunction::new()]
}

Check sample-plugin for an example plugin which exports some simple filters.

Supported Versions

All VapourSynth and VSScript API versions starting with 3.0 are supported. By default the crates use the 3.0 feature set. To enable higher API version support, enable one of the following Cargo features:

vapoursynth-api-31 for VapourSynth API 3.1
vapoursynth-api-32 for VapourSynth API 3.2
vapoursynth-api-33 for VapourSynth API 3.3
vapoursynth-api-34 for VapourSynth API 3.4
vapoursynth-api-35 for VapourSynth API 3.5
vsscript-api-31 for VSScript API 3.1
vsscript-api-32 for VSScript API 3.2

To enable linking to VapourSynth or VSScript functions, enable the following Cargo features:

vapoursynth-functions for VapourSynth functions (getVapourSynthAPI())
vsscript-functions for VSScript functions (vsscript_*())

Building

Make sure you have the corresponding libraries available if you enable the linking features. You can use the VAPOURSYNTH_LIB_DIR environment variable to specify a custom directory with the library files.

On Windows the easiest way is to use the VapourSynth installer (make sure the VapourSynth SDK is checked). The crate should pick up the library directory automatically. If it doesn’t or if you’re cross-compiling, set VAPOURSYNTH_LIB_DIR to <path to the VapourSynth installation>\sdk\lib64 or <...>\lib32, depending on the target bitness.