AI Video Character Replace swaps the person in an existing video clip for a new character image. Upload a source video and a replacement photo, and the output keeps the original motion, facial expression, camera movement, and scene atmosphere — the new character follows the source performance instead of appearing as a static overlay. Source video maximum is 200 MB; replacement image maximum is 20 MB (JPG/PNG/WebP).
How the replacement image affects the final result
The replacement image is the biggest variable in output quality. Characteristics that produce more natural-looking results:
What works well
- Subject is clear, background is clean or absent
- Facing forward or a slight angle, similar to the source video
- Even lighting, no strong shadows obscuring the face
- Single person, no other figures in frame
What can cause instability
- Large angle difference between replacement image and source video subject
- Source video has heavy motion blur
- Multiple people in the same frame
- Frequent wide head turns or the face is hidden for long stretches
When the replacement image angle closely matches the source video, the transition looks more cohesive. If the source subject is mostly facing left and the replacement image is front-facing, the substitution will have visible inconsistencies.
480p vs. 720p for character work
480p is the right choice when you are verifying whether the character swap looks correct overall — it processes faster and uses fewer credits. Switch to 720p when you need facial detail to read clearly, such as close-up shots, demo presentations, or clips intended for public release. The practical workflow is to confirm the result in 480p first, then re-run at 720p for the final version.
Clip length and what to expect
Processing time scales with video length. For a first pass, upload a 5–10 second clip rather than the full take — this confirms the character substitution looks right before you commit the longer runtime. The task runs asynchronously; progress is visible in the results panel.
::doc-callout{type="warning" title="Processing time">} Longer videos and higher resolution both increase wait time. Check the results panel after submitting rather than staying on the page. ::