What Does the VapourSynth R81 Release Change?

Updated

R81 is a maintenance release focused on Vulkan exportable memory. According to the project's release note, it fixes most of the Vulkan API misunderstandings and related issues introduced in R80, delivering exportable memory that actually works and noticeably faster GPU uploads. The practical takeaway: if you use Vulkan-based filters or move frames through exportable memory, upgrade from R80 to R81.

What R81 Fixes

The release note frames R80's problems as a mix of bugs and misunderstandings of the Vulkan API around exportable memory. R81 corrects those, with two stated outcomes:

  • Working exportable memory — the extension behaves as intended instead of failing or misbehaving.
  • Faster GPU uploads — the note credits the fixes with "much faster GPU uploads."

The note does not publish benchmark numbers, so treat "much faster" as the maintainer's characterization rather than a measured figure you can plan capacity around.

Platform Differences You Should Know

The release note spends most of its space on how exportable memory differs between Windows and everything else. These details matter if you write or debug Vulkan filters:

Behavior Windows Linux and other *nix
Exporting the same memory Only once; exporting again causes "weird behavior" Can be exported unlimited times
VRAM accounting after import The same exported memory counts twice toward process VRAM usage Not described as doubled in the note

The note presents these as undocumented quirks "nobody will tell you," with the hope that most users never need them. In practice, they explain two common symptoms: odd behavior when the same allocation is exported more than once on Windows, and VRAM usage readings that look inflated compared with what you allocated.

Who Should Upgrade

  • Vulkan filter authors — R81 is the version where exportable memory works as documented; testing against R80 will mislead you about API behavior.
  • Users of Vulkan-based processing chains — the upload speed improvement applies without configuration changes on your side.
  • Anyone still on R80 — the note's instruction is simply "Upgrade now."

If you do not use Vulkan features at all, the note describes no changes relevant to your setup, so there is no stated reason to prioritize the upgrade.

Limits of This Release Note

The note is short and does not cover:

  • Exact upload speed gains or benchmarks.
  • Whether non-Vulkan components changed.
  • Installation or upgrade steps beyond the recommendation to upgrade.

For those, check the release itself and the project's general documentation rather than assuming details the note does not state.