AviSynth vs AviSynth+ vs VapourSynth: which one should I choose?

Question

AviSynth is an old-but-still-useful tool for processing video via script, but I’ve noticed that there is a fork called AviSynth+ that appears to have some improvements. And then there’s VapourSynth rewritten to use Python.

What are the pros and cons of these versions?

For use-cases such as QTGMC deinterlacing and high-quality resizing, is one clearly better than the other?

Answer 1

There is no reason to use old, obsolete AviSynth — “old-but-still-useful” are almost all programs, but why to complicate your life with old, unsupported versions of them?

Every script for AviSynth works well in the AviSynth+, so even if you know AviSynth, there is nothing to relearn. The opposite is not true, however.

Use AviSynth+ (pros: all, cons: none), particularly pinterf/AviSynthPlus (forked from already dead AviSynth/AviSynthPlus).

---

Note:

The other situation is with GUI programs — if the old version satisfied you and the new one is too complicated, with changed menus, new icons, colors etc.

But it is not the case of AviSynth+ — you don't “see” the new commands, functions or parameters, so they don't disturb you.

Answer 2

As a summary of the differences:

AviSynth

• Outdated and no longer recommended for use
• Only available in 32bit – not able to use 64bit plugins/filters
• No multi-threading (unless you install AviSynth-MT, another fork, which is prone to errors and issues and no updates over last 4+ years)
• Older and only supports 8bit video
• Lacks support for some color spaces (YV16, YV24 etc.)
• Latest release over 3 years ago (May 2016)

AviSynth+

• Has both a 32bit and 64bit version, although the 32bit version apparently has some issues
• Supports multi-threading which can significantly improve rendering performance for some functions (similar to AviSynth-MT, another fork, but AviSynth+’s appears more stable)
• Be aware that using the 64bit version will require all plugins and filters to also be 64bit – and not all of them have 64bit versions. There are some filters that are 64bit only, however, which means you’re able to use those.
• QTGMC runs faster in multi-threaded more, and also apparently in 64bit mode
• AviSynth+ specific documentation is limited, but most of the great AviSynth wiki also applies to AviSynth+ and many pages now have notes mentioning any specific instructions for working with AviSynth+.
• Latest release 9 months ago (Dec 2018)

Note: be sure to get a recent version of AviSynth+ from https://github.com/pinterf/AviSynthPlus/releases – unfortunately the links from the main website (avs-plus.net) are outdated (from 2013).

Or you can use the Universal AviSynth Installer which allows you to easily switch between the different versions of AviSynth, AviSynth-MT, and AviSynth+ (32bit and 64bit).

VapourSynth

• Rewritten to use Python, a much more powerful and flexible scripting language
• Multi-threaded
• Supports generalized colorspaces whereby new or custom colorspaces can be specified at runtime
• Also runs on Linux, which is useful when you need to run it on a server
• Documentation isn't as detailed as AviSynth (it's not a community wiki)
• Regularly updated, with latest release Aug 2019