Modern VST3 effects in OBS Studio, with third-party plug-in code kept outside obs64.exe.
Public stable · Single VST3 Host + isolated serial VST3 Rack · premium compact Rack Editor · Input Trim / Output Fader · LUFS-I + dBTP metering · automatic working-Rack recall · native vendor GUIs · presets · fail-dry recovery
Website: https://masarray.github.io/obs-vst3/
Direct installer: https://github.com/masarray/obs-vst3/releases/latest/download/OBS-Safe-VST3-Host-Setup-x64.exe
Portable ZIP: https://github.com/masarray/obs-vst3/releases/latest/download/OBS-Safe-VST3-Host-Windows-x64-Portable.zip
Release notes: https://github.com/masarray/obs-vst3/releases/latest
OBS Studio's built-in VST filter does not provide VST3 hosting. Many current studio EQs, compressors, restoration tools, reverbs, saturators, limiters and mastering processors are distributed primarily—or only—as VST3.
OBS Safe VST3 Host adds two OBS-native workflows on Windows:
- VST 3.x Plug-in — a simple one-effect filter for the common case.
- VST3 Rack — a separate isolated serial multi-effect chain with a dedicated graphical Rack Editor and broadcast-oriented master console.
Third-party VST3 runtime code, vendor editors and plug-in scanning are deliberately kept outside the OBS process.
Download the latest stable Smart Installer directly
The stable URL above does not contain a version number. Release automation publishes it as an alias of the newest qualified installer, so documentation and landing pages do not need manual URL changes for every release.
Close OBS, run the installer, select the OBS root containing bin\64bit\obs64.exe, then start OBS again.
For advanced/manual installation:
Download the latest portable ZIP directly
Every release also publishes SHA256SUMS.txt for integrity verification.
Guides: Install · Compatibility · Safety model · Roadmap
v0.6.1 is the complete stable Rack refinement and reliability release built on the v0.6.0 serial-Rack foundation. It combines a compact broadcast-oriented Rack surface, real master gain controls and metering, flicker-free topology presentation, durable working-Rack recall and safer VST3 state persistence.
- Compact single-row effect strips reduce repeated UI noise and keep plug-in names readable.
- The slot health LED doubles as the enable/bypass control.
- Clicking a plug-in name opens its native vendor editor.
- One compact slot-action control handles replace, insert, move and remove operations.
- The Rack scrollbar reserves its layout gutter so adding effects does not shift row width, while remaining visually hidden until scrolling is needed.
- Pending topology changes keep the last committed Rack snapshot visible instead of flashing whole controls or transient state text.
- The Rack helper carries an OBS-companion Windows icon for taskbar, Explorer and title-bar identity.
- Input Trim sits before the serial VST3 chain and defaults to transparent
0.0 dB. - Output Fader sits after the chain and also defaults to
0.0 dB. - Both controls use lock-free transport and bounded one-block gain ramps to reduce zipper/click artifacts.
- Output attenuation remains authoritative on fail-dry output, so a plug-in failure does not unexpectedly jump an intentionally reduced level back to full scale.
- Stereo input/output peak meters reflect the signal around the Rack master path.
- LUFS-I measures integrated loudness in an ITU-R BS.1770 / EBU R128-style gated measurement shape.
- dBTP tracks reconstructed true peak with 4× quarter-sample interpolation and session-max hold.
- LUFS-I and dBTP observe the final post-output-fader signal delivered to OBS.
The Rack keeps its latest working chain automatically per OBS Rack filter. Named Rack presets remain available for reusable chains, but they are not required just to survive an OBS restart.
- Rack topology, bypass state and VST3 component/controller state are saved to a per-Rack durable session.
- OBS scene-collection serialization requests a bounded fresh state capture from the isolated Rack helper.
- Missing plug-ins remain safe pass-through placeholders rather than destroying saved state.
- CRC-protected atomic snapshot writes keep a last-known-good recovery path.
- If durable Rack storage is unavailable, the filter stays dry and reports Needs Attention instead of pretending the Rack is safely persistent.
- State capture establishes a bounded DSP-safe frontier before vendor
getStatework. - The realtime Rack path never waits on a control mutex; a capture conflict fails dry instead.
- Slow saved chains restore dry-first, then publish the complete restored generation atomically when ready.
- Save completion reports success/failure explicitly rather than turning completed failures into misleading timeouts.
- Split controller/processor VST3 plug-ins forward native GUI edits and preset-wide parameter resyncs into processor state before capture, improving full DSP recall after restart.
- Open Rack grants the isolated helper a foreground activation opportunity, so the Rack normally opens in front of OBS without becoming permanently topmost.
- Native vendor editor host windows use the embedded project companion icon instead of a generic Windows application icon.
- In OBS, open an audio source → Filters.
- Press + → VST3 Rack.
- Click Open Rack.
- Add effects in the graphical Rack Editor.
- Reorder, bypass or open each vendor UI as needed.
- Use Input Trim before the chain and Output Fader after the chain when level adjustment is needed.
- Watch final-output LUFS-I and dBTP for broadcast-oriented level awareness.
- Close/reopen OBS normally; the latest working Rack is recalled automatically.
- Use named Rack presets only when you want reusable named chains or deliberate snapshots.
The Rack remains a serial effects lane by design. It is not a free-form node graph.
The original VST 3.x Plug-in filter remains the simple choice when one effect is enough. It keeps automatic discovery, native vendor GUI, state persistence, scanner isolation, helper recovery and fail-dry behavior.
OBS Studio (obs64.exe)
│
│ bounded audio/control IPC
▼
obs-safe-vst3-host.exe
│
├── VST3 DSP
├── native vendor GUI
└── state/recovery
OBS Studio (obs64.exe)
│
│ independent Rack IPC
▼
obs-safe-vst3-rack-host.exe
│
├── compact graphical Rack Editor
├── Input Trim
├── VST3 A → VST3 B → ...
├── Output Fader
├── peak / LUFS-I / dBTP telemetry
├── vendor editor windows
├── durable working-session recall
├── named Rack presets
└── recovery / fail-dry policy
| Capability | Current stable |
|---|---|
| Windows x64 | ✅ Supported |
| OBS Studio 29.1+ | ✅ Supported compatibility floor |
| VST3 audio effects | ✅ Supported |
| Single VST3 filter | ✅ Stable |
| Serial multi-effect VST3 Rack | ✅ Stable |
| Compact isolated Rack Editor | ✅ Stable |
| Add / replace / remove / reorder / bypass | ✅ |
| Input Trim / Output Fader | ✅ Stable, real DSP controls |
| Stereo input/output peak meters | ✅ |
| LUFS-I integrated loudness | ✅ |
| dBTP reconstructed true peak | ✅ |
| Flicker-resistant topology transitions | ✅ |
| Automatic working-Rack recall across OBS restarts | ✅ |
| Native vendor editor | ✅ |
| Installed plug-in discovery | ✅ |
| Named Rack presets | ✅ |
| Mono / stereo Float32 | ✅ |
Crash/hang containment from obs64.exe |
✅ Architectural boundary |
| Sidechain / graph routing | 🚧 Future |
| MIDI / VST3 instruments | 🚧 Future |
| Arbitrary multichannel / Float64 fallback | 🚧 Future |
| macOS / Linux packages | Not currently shipped |
A specific third-party effect can still expose vendor-specific behavior. This project intentionally avoids claiming universal compatibility with every VST3 implementation.
The v0.6.1 runtime candidate was qualified on exact source head ce5eb052c97076df735b95b55328f76e222475ee before merge. That head includes the premium Rack UX/master-metering work and the durable persistence/state-safety changes. P0/P1, R0, R1, R2, R3, main CI and Compatibility Test Build were green on that exact head.
Rack UI/master work also carries deterministic contracts covering compact slot interaction, stable layout during topology changes, lock-free telemetry/control transport, Input Trim / Output Fader behavior, BS.1770-style integrated loudness structure and reconstructed true-peak reference cases.
Compatibility qualification covered Windows tests, scanner smoke, supported OBS loader/ABI-floor checks, package construction, PE inspection, portable validation and canonical OBS-root installer smoke.
Real OBS validation included repeated full OBS restarts while changing Rack/VST3 settings across sessions; the latest working chain and full VST3 DSP state restored successfully. The runtime candidate was merged as PR #109. The v0.6.1 release marker is a documentation/version descendant of that qualified runtime change.
The public release workflow rebuilds against pinned OBS/libobs and publishes the Smart Installer, portable ZIP and SHA-256 checksums only after its package tests pass. A follow-up release workflow publishes versionless stable aliases for the installer and portable package, which are the URLs used by the website and README.
See CHANGELOG.md for release-level notes and docs/rack/CURRENT_STATUS.md for the engineering status ledger.
Real-machine qualification across the project has included commercial effects from vendors such as:
- iZotope — Ozone / RX;
- FabFilter;
- Waves;
- Klevgrand;
- Neuro Audio;
- Process Audio.
Compatibility is evidence-based rather than implemented as a vendor whitelist. See the compatibility page.
Current Windows binaries are not commercially Authenticode-signed, so Windows can show Unknown publisher or a SmartScreen reputation warning.
Do not disable Defender or SmartScreen globally. Download only through the official repository/website links and verify SHA256SUMS.txt when you want an additional integrity check.
This project provides crash containment, not a malware sandbox. A VST3 is native code and still runs with your Windows user permissions inside the helper process. Only install plug-ins from vendors you trust.
The design reduces the failure surface by keeping third-party VST3 DSP, vendor UI and scanning outside obs64.exe, using bounded realtime behavior and failing to dry/pass-through audio when a valid wet result is unavailable. It cannot guarantee that OBS, Windows, drivers, hardware or malicious native code can never fail.
Read the exact security and crash-isolation model.
- Product roadmap
- North Star PRD
- Single Host architecture
- Rack architecture and execution docs
- Windows installation notes
- Security policy
- Contributing
- Third-party notices
Project code: GPL-3.0-or-later. See LICENSE.
The Steinberg VST3 SDK used by the build is MIT-licensed; see THIRD_PARTY_NOTICES.md.
VST is a trademark of Steinberg Media Technologies GmbH. OBS is a trademark of its respective owners. This independent open-source project is not endorsed by Steinberg or the OBS Project.