Edit background is the Edit Video tool that replaces the background of a video while keeping the subject. You can supply a background image, describe the background you want, or do both.
What does Edit background do?
It swaps out the background behind your subject. You choose how to define the new background using two modes at the top of the panel:
Image + Prompt — upload a background image, optionally with extra text guidance.
Prompt — describe the background in words only, with no image.
How do I run an Edit background edit?
Open Edit Video and pick Edit background from the tool switcher.
Add the video with Select content or Upload video.
Pick a mode — Image + Prompt or Prompt.
Upload a background image and/or type a description (see below).
Adjust quality and resolution in the bottom bar if needed.
Click Generate — the cost is shown next to the button.
What's the difference between the two modes?
Image + Prompt shows an upload area ("Upload background image", PNG or JPG up to 10 MB) plus a prompt box. The prompt is optional here — its placeholder reads "Additional information about your uploaded background (Optional)."
Prompt hides the image area and just gives you a prompt box with the placeholder "Describe the background you want." Here the description is required.
You can switch modes at any time using the toggle at the top.
How long can the description be?
The prompt box holds up to 4,000 characters, with a live counter. In Image + Prompt mode the text is optional; in Prompt-only mode a non-empty description is required.
Why is Generate disabled?
Generate stays off until you've added a video and satisfied the current mode:
In Prompt mode you need a non-empty description.
In Image + Prompt mode you need an uploaded image — and you'll be asked to wait if the upload hasn't finished. (If you'd rather not upload an image, switch to Prompt-only mode.)
Best supports 480P, 720P, and FHD for selected slices between 4 and 15 seconds; Ultra and UltraS accept between 4 and 30 seconds. The hint below the source-video controls updates between "Use a video between 4 and 15 s." and "Use a video between 4 and 30 s." with the selected quality. A clip under 4 seconds shows "The video must be at least 4 s." On Best, if the clip exceeds 15 seconds, use the scissors button in the bottom bar to shorten it. Best is powered by Seedance 2.0, while Ultra and UltraS are powered by Seedance 2.5; hover a quality on desktop, or tap its info icon on mobile, to see the model note.
On mobile
The mode toggle, image upload, and prompt box stack below the video. Uploads show progress with a delete button, and switching modes shows or hides the image area just like on desktop.
Related: Edit Video overview · Edit product · Edit style