Introduction

This provides some flavor about how to use it.

Python vs Nim syntax

This sections aims to give you an idea about how you normally do things in Python and how can you do it in Nim

Open a file, transpose it and play it

Python

Create script.vpy with:

from vapoursynth import core
video = core.ffms2.Source(source='videofile.mkv')
video = core.std.Transpose(video)
video.set_output()

and play it like:

$ vspipe --y4m script.vpy - | ffplay -i pipe:

Nim

Create script.nim:

import vapoursynth
Source("videofile.mkv").Transpose.Pipey4m

Compile it:

$ nim c -d:release -d:danger --threads:on script.nim

and then you can play it like:

$ ./script | ffplay -i pipe:

Current status

It can load videos, transform them and pipe them to stdout (or store them in a file).

Currently, the following plugins are supposed to work (they need to be installed in your environment).

How to implement Nim functions as filters is shown in:

Some examples

Piping a video

import vapoursynth
Source("video.mkv").Pipey4m

Selecting the first 100 frames

import vapoursynth
Source("video.mkv")[0..100].Pipey4m

Aplying one of VapourSynth functions (ex. Transpose)

import vapoursynth
Source("video.mkv")[0..100].Transpose.Pipey4m

Functions can be chained because, rather than a clip, the input is always a ptr VSMap. Given that invoke returns ptr VSMap.

Aplying one function from a plugin

The are two requirements in order to be able to use a function from a plugin:

  • The plugin needs to be installed in your computer
  • The plugin needs to be wrapped. You can find a list of the plugins already wrapped here.

Note that this wrappers are created automatically. You just need to install any plugin in your computer and then execute plugin_generator. It will create the folder plugins for all the available plugins in your computer.

Then the function is called directly. For instance, the already used function Source is provided by the plugin ffms2:

import vapoursynth
Source("video.mkv").Pipey4m

Passing parameters

Mandatory parameters are passed straight away, like in the case of Source, where we just put the name of the file:

Source("video.mkv")

Passing list parameters

In Nim the equivalent to lists are called sequence, and they are written like: @[1, 2, 3].

For example, if you use the plugin motionmask:

import vapoursynth, options
Source("video.mkv").MotionMask( th1= some(@[10, 10, 10]), th2= some(@[10, 10, 10]), tht=some(10), sc_value=some(0)).Pipey4m

Not only chaining functions is possible

You can store the videos in variables:

import vapoursynth, options
let clip1 = Source("video.mkv")

let clip2 = MotionMask( clip1, th1= some(@[10, 10, 10]), th2= some(@[10, 10, 10]), tht=some(10), sc_value=some(0))

Pipey4m(clip2)
#Or you could pipe the first clip:
#Pipey4m(clip1)

Additional notes.

TODO

  • [DONE] Helper functions for +, [], …

    • [DONE] Some functions no write filters

  • Better documentation

  • [WON’T WORK] Does it work with nimscript? Given Nimscript limitation: “Nim’s FFI (foreign function interface) is not available in NimScript. This means that any stdlib module which relies on importc can not be used in the VM.”

  • Github pages

  • To enable dealing with frames like an array.

  • To enable loading plugins manually.

  • To enable loading AVS scripts (for instance for deinlerlacing). Options are AviSource. VS_AvsReader and vsavsreader

  • To take a look at Home Of VapourSynth Evolution

  • To compare with this filter in pure python

Vapoursynth Tutorial

https://hackmd.io/@Se1ry_ZUSminEO7QQyVHAQ/HJwtY1WV7?type=view

Avisynth

https://forum.doom9.org/showthread.php?t=175141 https://forum.doom9.org/showthread.php?t=165957

AddGrain,


Last modified January 1, 0001