How to Use Transparent Video in OBS
Last updated: · Written by the RenderAlpha team
Facts checked against the sources below on November 9, 2026. OBS itself was not tested; browser results are from Chrome 152, Firefox 153 and Safari 18.6 on macOS 15.6.1.
Most “black box in OBS” problems come from one of two places: the file has no alpha channel, or a Media Source setting is wrong. This guide separates the two, using only what OBS documents and what we could test ourselves.
Short answer
Add the file as a Media Source, but first confirm the file itself is transparent by opening it in Chrome or Firefox over a colored page. OBS’s Media Source page lists .webm and .mov among supported file types, and it does not describe alpha behavior. If the file is transparent in a browser, change one documented Media Source setting at a time. We did not test OBS itself.
Step 1: prove the file is transparent before you open OBS
An MP4 with H.264 has no alpha channel, so no OBS setting can create transparency from it. Our test MP4 reports pix_fmt=yuv420p, a format with no alpha plane. Start with the file.
In our test on macOS 15.6.1, a 5 second VP9 WebM with alpha came back transparent in Chrome 152 and Firefox 153, and opaque in Safari 18.6 (see why transparent WebM turns grey or black in Safari). Load your file the same way in Chrome or Firefox over a colored page. If it shows the page color, the file is good and the problem is in OBS. The commands in how to create a transparent WebM also read the file’s metadata.
Step 2: add it as a Media Source
OBS’s Media Sources page lists the supported file types, including .webm, .mov, .mp4 and .gif. In the Sources panel click +, choose Media Source, and select the file.
A file that is already transparent does not need a Chroma Key or Color Key filter, so skip it unless you see leftover color.
The Media Source settings OBS documents
These are the property names and defaults from OBS’s Media Source page. The page describes some of them and does not say which affect transparency, so change one at a time and compare against the file you checked in step 1.
| Setting | Default (per OBS) | Notes |
|---|---|---|
| Loop | Off | Listed by OBS. Turn it on for an overlay that should keep playing. |
| Restart playback when source becomes active | On | Listed by OBS. For a one-shot alert, leave Loop off and keep this on. |
| Use hardware decoding when available | Off | OBS describes it as setting the GPU to perform hardware decoding on certain file types if your GPU has the decoder. |
| Close file when inactive | Off | OBS describes it as freeing memory by unloading the file when it is hidden or not on the current scene. |
| Apply alpha in linear space | Off | Listed by OBS without a description. Try it if soft edges look too dark or too light. |
Dark or light fringes around soft edges
A fringe of color around soft edges can come from a straight-versus-premultiplied mismatch rather than a missing alpha channel. Adobe’s documentation explains the difference: premultiplied channels are multiplied with a background color, usually black or white, while straight channels keep color and transparency separate. If you see a dark halo, re-export from a tool that writes straight alpha, or try the Apply alpha in linear space setting above. We could not confirm in OBS which fix applies to your file.
Alerts and stingers
For an alert that should play once each time it is shown, leave Loop off and keep Restart playback when source becomes active on. If your alerts come from a service as a widget URL, add that URL as a Browser Source instead.
OBS’s stinger page describes two cut-point modes, by milliseconds or by frame number, and a track matte mode that uses a single video with the matte beside the picture. It does not mention alpha, so we do not claim a transparent WebM works as a stinger. Check that page for the current options.
What we did not test
We did not run OBS for this guide, so the settings above are documented behavior and not our own measurements. RenderAlpha works on files you upload and does not remove your webcam background live; for that, use an OBS plugin or your camera software. To turn a clip into an overlay, see how to export a video with an alpha channel and the format comparison.
Frequently asked questions
Does OBS play transparent WebM?
OBS’s Media Source page lists .webm among supported file types but does not describe alpha behavior, and we did not test OBS. Confirm the file is transparent in Chrome or Firefox first, then test it in your OBS version.
Why is my overlay a black box in OBS?
Most often the file has no alpha channel, for example an H.264 MP4. Check it over a colored page in a browser and with ffprobe before changing OBS settings.
Should I add a Chroma Key filter to a transparent file?
No. A transparent file already has its background removed. A key filter works on color and can only affect the edges.
Can I use ProRes 4444 in OBS?
OBS lists .mov among supported file types, and Apple says ProRes 4444 carries alpha. We did not test that combination in OBS, and the files are much larger than WebM, so keep ProRes for editing. See ProRes 4444 with alpha.
Does this work for a live webcam?
No. RenderAlpha processes uploaded files only. For a live background removal, use an OBS plugin or your camera software.
Sources
Primary sources we checked. The date is when we last opened each page.
- OBS Studio: Media Sources: supported types and properties (Retrieved )
- OBS Studio: Track Matte Stinger Transitions: cut points and track matte mode (Retrieved )
- Adobe: Importing and interpreting footage items: straight and premultiplied alpha (Retrieved )