How do I make a transparent video overlay for OBS?
To make a transparent overlay for OBS or Twitch, export the animation or cut-out clip as VP9 WebM with an alpha channel, then add it in OBS as a Media Source with Loop enabled if it should repeat. Don't add a Chroma Key filter — the transparency is already in the file. Use ProRes 4444 MOV only if you need an editing master; it works in OBS but is much larger. MP4 can't carry the transparency.
Updated
Which file for which overlay
| Overlay type | Export | OBS source | Notes |
|---|---|---|---|
| Looping corner logo or lower third | VP9 WebM with alpha | Media Source, Loop on | No chroma key |
| One-shot alert | VP9 WebM | Media Source, Restart playback when source becomes active | Leave Loop off if it should play once |
| Scene transition | VP9 WebM | Stinger transition | Stinger guide. Not the same as a Media Source. |
| Web-hosted overlay | WebM in an HTML page | Browser Source | OBS Browser Source uses CEF, which is Chromium |
| Editor round-trip | ProRes 4444 MOV | Media Source | Large files. ExportAlpha ProRes is limited to 8 seconds. |
Export an OBS-ready transparent WebM
Upload a clip, download VP9 WebM with alpha, then add it as a Media Source. Do not add a chroma-key filter.
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Animated text is usually an editor export
A lower-third or animated title is normally built in After Effects, DaVinci Resolve, or a motion tool, then exported with alpha from that project. You do not need background removal for a title that was already transparent. ExportAlpha fits a filmed person or product that still has a room behind it and needs to become an overlay. Export the title from the app that made it.
What OBS documents
The OBS Media Source page lists supported video types as ".mp4, .ts, .mov, .flv, .mkv, .avi, .gif, .webm" and includes "Apply alpha in linear space" (default off). Loop defaults to off. "Restart playback when source becomes active" defaults to on. The page does not name VP9 or guarantee every codec inside those extensions. Official page: OBS Media Sources (retrieved October 9, 2026).
Method 1: Media Source (local file)
- Export your video as VP9 WebM with alpha (yuva420p).
- In OBS: Sources → Add → Media Source.
- Browse to your .webm file.
- Check Loop if the overlay should repeat. That option does not promise a seamless join.
- Do not add a Chroma Key filter when the file already has alpha.
Method 2: Browser Source (web URL)
- Host the transparent WebM.
- Create an HTML page with a video element that plays the file.
- In OBS: Sources → Add → Browser Source.
- Paste the URL of that HTML page.
OBS Browser Source uses CEF (Chromium Embedded Framework), so it follows Chromium rather than Safari. Browser Source documentation: OBS Browser Source.
Layer order
Place the overlay above the game capture, camera, or other base sources. In OBS, sources higher in the list appear on top. If the overlay is underneath, it will be covered.
If the overlay has a black box
- The file is everyday H.264 MP4. Re-export VP9 WebM with alpha.
- You captured a player window. Use Media Source on the file itself.
- A Chroma Key filter is on a file that already has alpha. Remove the filter.
Safari showing grey on a web page is a different bug. See why an export loses transparency.
What this tool is not
ExportAlpha is not an OBS plugin. It does not remove a webcam background during a stream, and it is not a virtual camera. You upload a file, download WebM or a short ProRes MOV, then place that file in OBS.
Frequently Asked Questions
Can I use a transparent video overlay in OBS?
Yes. Add a VP9 WebM with alpha as a Media Source, or a page that plays that WebM as a Browser Source. Do not add a Chroma Key filter if the file already has alpha. This is a file overlay, not live camera background removal.
Does OBS support WebM in Media Source?
OBS Media Source documentation lists video file types as .mp4, .ts, .mov, .flv, .mkv, .avi, .gif, and .webm, and it includes an option named Apply alpha in linear space. That list does not name VP9 or yuva420p. VP9 WebM with alpha is the file this site exports for overlays. Test the export in your OBS version.
Can I use a transparent MOV in OBS?
Yes. OBS lists .mov as a Media Source video type, and ProRes 4444 stores alpha. The file is much larger than WebM. ExportAlpha's ProRes 4444 export is limited to 8 seconds. Use WebM for a longer overlay.
Why does my OBS overlay have a black box?
The file is often an everyday MP4 with no alpha, a chroma key filter was added on top of a file that already has alpha, or the source is a window capture of a player that paints black. Use Media Source and a WebM with alpha, and remove the chroma key.
How do I make the overlay loop without a gap?
In Media Source, check Loop. OBS documents Loop as off by default, and Restart playback when source becomes active as on by default. Loop plays the file again when it ends. This page does not claim the join is seamless.
Can I use this tool for live camera background removal in OBS?
No. ExportAlpha processes an uploaded file. It is not an OBS plugin, a virtual camera, or a live key. For a live camera you need different software.
Can I use HEVC-with-alpha in OBS?
HEVC in OBS Media Source depends on system codecs. It is less certain on Windows and Linux than on a Mac with HEVC support. VP9 WebM is the file this site recommends for OBS. ExportAlpha does not export HEVC-with-alpha.
Sources
- OBS Media Sources: Official KB (retrieved October 9, 2026)
- OBS Browser Source: Official KB
Create the overlay file
Upload the clip, export transparent WebM, and add that file as an OBS Media Source.
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