Transom Errors & codecs
All ffmpeg output is logged to the browser console as [ffmpeg] .... The field translates common failures into plain English.
Error reference
Section titled “Error reference”| Symptom | Message shown | Fix |
|---|---|---|
hevc / h.265 in log | ”This video uses H.265/HEVC…” | Should decode fine. If it fails, re-export as H.264. |
No such encoder / codec not found | ”The required codec isn’t available…” | The preset uses a codec not in this WASM build. |
not currently supported in container | ”The codec doesn’t work with the output container…” | Check that ffmpegArgs and outputExtension match — VP9 needs .webm. |
Cannot determine format / Invalid data found | ”The file couldn’t be read…” | File may be corrupted or in an unsupported container. |
out of memory / OOM | ”The browser ran out of memory…” | Use a shorter clip, a lower-resolution preset, or close other tabs. |
| Anything else | Raw last 5 ffmpeg log lines | Check the browser console for the full [ffmpeg] trace. |
Supported input formats
Section titled “Supported input formats”| Codec | Via |
|---|---|
| H.264 | Built-in ffmpeg decoder |
| H.265 / HEVC | Built-in ffmpeg decoder |
| AV1 | libdav1d (fast) + libaom |
| VP8 / VP9 | libvpx |
| ProRes | Built-in ffmpeg decoder |
| DNxHD / DNxHR | Built-in ffmpeg decoder |
| MPEG-2, MPEG-4 | Built-in ffmpeg decoder |
| Containers | .mp4, .mov, .webm, .avi, .mkv, .m4v |
Supported output formats
Section titled “Supported output formats”| Format | Via |
|---|---|
H.264 .mp4 | libx264 |
VP9 .webm | libvpx-vp9 |
| AV1 | libaom-av1 |
| Opus audio | libopus |
| AAC audio | Built-in ffmpeg encoder |
Cross-origin isolation warning
Section titled “Cross-origin isolation warning”If the field shows “Video Scribe requires cross-origin isolation” but a video is already saved, this is expected. It means the browser context doesn’t have SharedArrayBuffer — which happens in Craft’s Live Preview editor pane when the CP and preview are on different origins. The saved video still displays; uploading is disabled until you’re back in a fully isolated context (the regular CP editor).
See Server setup to enable isolation in multisite installs.