Which transparent video format should I export?
The right format depends on where you'll use the video. There's no universal transparent format that works everywhere. Choose based on your target platform.
Export the format that matches the destination
WebM for Chrome, Firefox, and OBS. ProRes 4444 MOV for Premiere, Resolve, and Final Cut.
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Decision table
| Use case | Export format | Don't use |
|---|---|---|
| Chrome / Firefox web | VP9 WebM, pixel format yuva420p | H.264 MP4 |
| Safari / iOS web | HEVC-with-alpha (MOV or MP4 container, hvc1 codec) | WebM only |
| Premiere / Resolve / Final Cut | MOV ProRes 4444 | H.264 MP4; don't convert WebM to ProRes (quality loss) |
| OBS local overlay | VP9 WebM, Media Source | MP4 with chroma key workaround |
| Finished deliverable for clients | H.264 MP4 with background already composited | Don't pretend it has alpha |
Detailed breakdown
Chrome / Firefox web: VP9 WebM
WebM with VP9 codec and yuva420p pixel format is the standard for transparent video on the web. Chrome and Firefox both support it. File sizes are reasonable for web delivery. Safari doesn't composite WebM alpha, so serve HEVC-with-alpha as an alternative source.
Safari / iOS web: HEVC-with-alpha
Apple HEVC Video with Alpha works on Safari 13+, iOS 13+, and macOS Catalina+. Use it in a MOV or MP4 container with the hvc1 codec identifier. Serve it first in your source tags so Safari picks it, then list WebM as fallback for Chrome/Firefox.
Editing: ProRes 4444 MOV
ProRes 4444 (or 4444 XQ) is the editing standard. Premiere, Resolve, and Final Cut all support it. It's large but maintains quality through multiple edits. ProRes 422 and below do not support alpha—only 4444 and 4444 XQ do.
OBS: VP9 WebM for Media Source
OBS Media Source reads VP9 WebM with alpha. Don't add a Chroma Key filter—if you need chroma key, your file doesn't have alpha. See the OBS guide for setup details.
Formats to avoid
- H.264 MP4: Doesn't support alpha in everyday workflows. Transparent regions get filled with black or white.
- Converting WebM to ProRes: If you already have transparent WebM, import it directly. Converting adds quality loss. Export ProRes from the original source.
- Only WebM for Safari users: They'll see black backgrounds. Always provide HEVC-with-alpha for Safari.
What about CapCut / iMovie / DaVinci Resolve?
缺口: Public documentation on whether these editors import WebM with alpha is contradictory. CapCut claims vary by version. iMovie traditionally doesn't support WebM. DaVinci Resolve Studio supports many formats, but free versions may not.
Recommendation: Test with your current software version. If WebM doesn't import with alpha, use ProRes 4444 MOV instead.
Frequently Asked Questions
Can I use one format for all platforms?
No. Web browsers need WebM or HEVC. Editing software needs ProRes or a compatible intermediate. OBS needs WebM or MOV. Choose the format based on your specific use case.
Should I export both WebM and HEVC?
If you're serving video on a website that must work in both Chrome and Safari, yes. Use multiple source tags. Safari will pick HEVC, Chrome will pick WebM. This is the standard cross-browser approach.
What about PNG sequences?
PNG sequences are uncompressed and enormous. They're used for final compositing in professional pipelines but not practical for web delivery or casual editing. Stick with ProRes for editing or WebM for web.
Sources
- Apple ProRes support: Official support page
- WebM VP9 alpha: WebM Project
- OBS Media Source: OBS Knowledge Base
Export the right format for your use case
Upload your video and export transparent WebM for web or ProRes MOV for editing.
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