README.md

About

This project aims to wrap VapourSynth's API 4 version.

Status

Right now it is possible:

• to play and transform videos
• to play audio

Differences with original project

1. In order to allow chaining function calls, the first argument of a function is always a VSMap and all functions return VSMap. For that reason, functions are created within the folder src/plugins4.
2. Those functions my receive optional paramenter. In Nim, I decided to use std/options for that. This is why you might see in some examples values like: -1.some or none(whatever).

Development

API

https://vapoursynth.com/doc/api/vapoursynth4.h.html

Wrapping

The library was wrapped using [futhark]. The file create.nim will create the files:

• vapoursynth4.nim
• vsconstants4.nim

lib/ provides a friendlier API.

An api instance is created in libapi.nim and also a core instance in helper.nim.

VSMaps are like python's dictionaries.

Plugins

Plugins are files that provide a number of functions when loaded.

There some functions to deal with the plugins available.

Other set of functions are to deal with the functions available within a plugin.

Then invoke is used to call one of those functions with parameters.

For instance, Source is function within the plugin ffms2 and we can call it using invoke.

The file wrapper/plugin_generator.nim is used to create the files contained in plugins4. These defines Nim functions with Nim times that help calling the functions defined in the plugins. This way we won't need to use invoke. These definitions use invoke by us.

The function "Source" from BestAudioSource has been renamed into "asource". This avoids having to specify if we are referring to ffms2.source or bas.source. We will use source and asource instead.

Comparing Nim and python

Python

Create the file demo.vpy:

import vapoursynth as vs
audio = vs.core.bas.Source("file_example_MP3_700KB.mp3", track=-1)
video = vs.core.std.BlankClip()
video.set_output(0)
audio.set_output(1)

vspipe -o 1 -c wav "demo.vpy" - | ffmpeg -i pipe: -c:a pcm_s16le Output.wav
vspipe -o 0 -c y4m "demo.vpy" - | ffmpeg -i pipe: -i Output.wav -c:v prores -c:a copy "Output.mkv"
rm Output.wav

Nim

TBD

Link

https://forum.doom9.org/showthread.php?t=173194 https://vapoursynth.com/doc/pythonreference.html#VideoNode.set_output

TODO

• Memory issue with tests/ex06_adding.nim and tests/ex07_repeating.nim

  • https://nim-lang.org/docs/destructors.html

• Slicing a video clip

• Slicing an audio clip

• Custom filters: https://mantielero.github.io/VapourSynth.nim/docs/filters/

  • I managed to create Nim based filters as performant as C++ but leveraging Nim's macros.
  • python example: https://forum.doom9.org/showthread.php?t=172206
  • c example: crop filter in std

• libnut support:

  • https://github.com/lu-zero/nut/blob/master/src/libnut/libnut.h
  • https://ffmpeg.org/nut.html

• Low priority:

  • being able to use VapourSynth python scripts.
  • supporting Avisynth plugins.
  • AviSynth scripts: is this possible?
  • Supporting more formats: I have not investigated much in this front.
  • Interop with other libraries:
    • Cairo (or Skia, which should be more performant),
    • OpenCV
    • ...
  • Look for some inspiration in MoviePy:
    • For example, making easier the composition/position of clips.

• VSMap:

  • mapSetEmpty
  • mapGetIntSaturated
  • mapGetFloatSaturated
  • mapGetDataTypeHint
  • mapConsumeNode
  • mapConsumeFrame
  • mapConsumeFunction

Blablabla

VSMap

Links

https://hackmd.io/@nibreon/vapoursynth-book/%2F%40nibreon%2Fvapoursynth-book https://forum.doom9.org/forumdisplay.php?f=82

Plusgins

https://vsdb.top/

Transitions

yay -S vapoursynth-plugin-vstransitions-git