OBS Native Plugin

The production OBS path is a Mimir/Fensalir-owned program texture plus a Mimir/Fensalir-owned stem bus, exposed through a narrow native OBS plugin.

Authority

Fensalir owns the completed program pixels.
Mimir/Fensalir own timing, alignment, DSP, and stem identity.
OBS owns broadcast mixing and scene composition.
The plugin imports already-produced program pixels and reads already-processed stem samples. It does not synchronize raw sources, estimate clocks, render the field, or decide which payload is true.

Current Contract

Video

Fensalir publishes the completed backbuffer into a named shared D3D12 B8G8R8A8_UNorm texture when these environment variables are set:

FENSALIR_PROGRAM_OUTPUT_D3D12=1
FENSALIR_PROGRAM_OUTPUT_NAME=Global\MimirFensalirProgramTexture

The native OBS plugin in native/obs_stem_source exposes a Mimir Program Texture video source. Set:

Shared D3D12 texture name: Global\MimirFensalirProgramTexture

OBS/libobs is D3D11 internally on Windows, so this source opens the named D3D12 texture, creates an OBS-readable shared D3D11 texture, and performs a GPU-to-GPU copy during OBS render before drawing the source. This avoids CPU readback and does not require Spout2. It is not pure zero-copy yet; the remaining copy is the D3D12-to-libobs-D3D11 boundary.

Audio

MimirObsStemSharedMemoryPublisher writes the latest validated MimirObsStemPublicationSnapshot into a Windows shared-memory map named Local\MimirObsStemBus by default. The native OBS plugin in native/obs_stem_source exposes a Mimir Audio Stem input source. Add one source per stem and set:

Shared memory map: Local\MimirObsStemBus
Stem id: aligned_source_0

Use aligned_source_0 through aligned_source_5 for the first actuator-stage source lanes.

Build

.\scripts\build-obs-stem-plugin.ps1

The script stages obsproject/obs-plugintemplate under artifacts/obs-sdk/, lets the upstream template fetch/build the matching OBS/libobs development surface, then builds native/obs_stem_source against that SDK. The staged SDK and native build products are local artifacts, not repository state.

The managed shared-memory publisher is verified by:

dotnet run --no-build --project .\src\Mimir.BufferSmoke\Mimir.BufferSmoke.csproj -- --obs-stem-shared-memory-smoke

The local native plugin build currently succeeds and emits:

native\obs_stem_source\build\Release\mimir_obs_stem_source.dll

That DLL currently registers both source types:

Mimir Program Texture
Mimir Audio Stem

Install

For a standard Windows OBS install:

.\scripts\install-obs-mimir-plugin.ps1

For a portable OBS tree:

.\scripts\install-obs-mimir-plugin.ps1 -ObsRoot D:\Tools\obs-studio

The script copies the built DLL into obs-plugins\64bit. It does not create scene items or alter OBS profiles.

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