Prepare footage before a video-editing upload
Prepare drone and phone clips before a large upload. Keep your source files, download cloud copies and test a small sample in the editor first.
A little preparation can make an upload problem much easier to understand. The aim is not to pre-edit every useful moment. It is to establish that you have the intended original files, that they play, and that the editor accepts a representative sample.
Keep preparation separate from creative selection. You should not have to create a finished montage merely to test whether a file can enter the workflow.
Keep an untouched copy
Make sure there is a copy of the camera originals outside the project you are editing. Give the project folder a useful name and keep exports in a different location. This prevents a smaller delivery copy from being mistaken for the source later.
Do not remove a memory-card original solely because a preview or thumbnail appears in another app. Verify that the copy has completed and can be played before relying on it.
Confirm the file is actually local
A photo-library item can appear in a gallery while its full-resolution media is stored elsewhere. Check whether the original has finished downloading to the device you are using. A placeholder or incomplete transfer is a different problem from an unsupported codec.
Open the file in a local player and inspect its beginning, middle and end. Note whether playback works and whether the visible properties match the recording you expected.
Record the properties that help troubleshooting
Useful details include the container, codec, width and height, frame rate and whether the recording uses HDR or a log profile. Do not assume that all MP4 files have the same encoding. The MDN codec guide distinguishes codecs from the containers that carry them.
If a tool does not show these details, report what you can verify rather than guessing. The original camera settings can be useful context, but the properties of the actual file are the stronger reference.
Try a representative sample
Choose a short file from the same recording settings as the larger project. Test import, preview and a small export. A sample from a different phone or capture mode may not exercise the issue you care about.
This is a compatibility check, not a speed benchmark. One successful small file does not establish that every larger file or network condition will work identically.
Capture an error without exposing private material
Record the visible error, the stage, the time, the browser and the device. Do not include passwords, session tokens or private sharing links. Share footage only through an agreed support route and only when you have the necessary permission.
Use the file-size calculator for planning, then read Stitch's platform status before deciding which device to use. Keep the source files until the final output has been downloaded and checked.