Can I use a transparent video overlay in OBS?

Yes. This is for overlaying pre-rendered video files, not real-time camera background removal. Use Media Source for local WebM files or Browser Source for web-hosted videos.

Method 1: Media Source (local file)

For transparent video files stored on your computer:

1. Export your video as VP9 WebM with alpha (yuva420p pixel format)
2. In OBS: Sources → Add → Media Source
3. Browse to your .webm file
4. Check "Loop" if you want the overlay to repeat
5. Do not add a Chroma Key filter—if you need chroma key, your file doesn't have alpha

Media Source reads local files. OBS supports .webm and .mov. VP9 WebM with yuva420p is the community standard for transparent overlays.

Method 2: Browser Source (web URL)

For videos hosted on a web server:

1. Upload your transparent WebM to a web server
2. Create an HTML page with a video element that plays the file
3. In OBS: Sources → Add → Browser Source
4. Paste the URL to your HTML page

OBS Browser Source uses CEF (Chromium Embedded Framework). It behaves like Chrome, which supports WebM alpha. The default CSS sets the background to transparent, so the alpha channel composites correctly.

Official documentation: OBS Browser Source KB

Layer order

Place your transparent video overlay above your game capture, camera, or other base sources. In OBS, sources higher in the list appear on top.

If the overlay is below your main content, it will be covered. Check layer order if your overlay isn't visible.

Loop settings

• For persistent overlays (e.g., corner branding): Check "Loop" in Media Source properties
• For one-time alerts (e.g., donation notifications): Uncheck "Loop" and optionally check "Restart when active" to replay each time the source is shown

Troubleshooting black background

If your overlay appears with a black background:

• File doesn't have alpha: The file is likely H.264 MP4. Re-export as VP9 WebM with alpha.
• Wrong source type: If you used Window Capture or Display Capture instead of Media Source, OBS captures the player window—which may composite onto black. Use Media Source.
• Chroma Key filter added: If your file has alpha, don't add chroma key. Remove the filter.

Verify your WebM has alpha by checking with ffprobe or importing into Chrome over a colored div. See why transparent videos appear black.

What this tool is NOT

This is not an OBS plugin. This tool processes uploaded video files (file-based workflow). It does not:

• Remove your webcam background in real-time during a stream
• Act as a virtual camera or OBS filter
• Process live video feeds

For real-time camera background removal, you need an OBS plugin or virtual camera software. This tool creates transparent video files you can then overlay in OBS.

Format recommendations

• Best for OBS: VP9 WebM with yuva420p
• Also works: MOV with ProRes 4444 (much larger file size)
• Don't use: H.264 MP4 (no alpha), or WebM without alpha

Frequently Asked Questions

Does OBS officially guarantee WebM alpha support?

OBS Media Source documentation lists .webm and .mov as supported formats and mentions "Apply alpha in linear space" option. VP9 WebM with yuva420p is the widely used community standard for transparent overlays. Official docs don't list every codec variant. If in doubt, test your export.

Can I use HEVC-with-alpha MOV in OBS?

**缺口:** HEVC support in OBS Media Source depends on system codecs and platform. On macOS with native HEVC support, it may work. On Windows/Linux, it's less certain. VP9 WebM is the safer choice for cross-platform OBS overlays.

Why do some people still use chroma key for overlays?

Legacy workflows or lack of awareness. If your file has a proper alpha channel, chroma key is unnecessary. Chroma key was the standard before transparent video formats became widely supported. If you're adding chroma key to make transparency work, your file probably doesn't have alpha—re-export it correctly instead.

Sources

• OBS Media Sources: Official KB
• OBS Browser Source: Official KB