AI Video Rotoscoping Tutorial
Step-by-step AI video rotoscoping workflow inside Flixly. Uses Veo 3.1 and Kling 3.0 on 1080p clips to produce clean mattes in under 30 minutes with exact credit counts and settings.
TL;DR
Upload a 15-second 1080p clip, run Kling 3.0 via video-to-video for 48 credits, refine masks with reference-to-video at 0.85 consistency, then export a ProRes 4444 matte. The process takes five tool calls and finishes in roughly 25 minutes.
A 15-second 1080p product demo clip arrives at 2:15 pm and the final edit must ship by 3 pm with the foreground object cleanly separated from the background.
Prepare the source clip
Load the raw footage into the video editor first. Confirm the file runs at 24 fps and stays under 200 MB so the upload completes in one pass. Export a 720p proxy if the original sits at 4K to speed up the first test pass.
Select the right model
Flixly surfaces Veo 3.1 and Kling 3.0 on the Video to Video page. Veo 3.1 handles fine edge detail on moving fabric while Kling 3.0 processes 4K input at 12 fps without dropping frames. Choose Kling 3.0 when the clip contains rapid camera movement.
Model comparison
| Model | Max resolution | Typical credits per 15 s | Edge fidelity |
|---|---|---|---|
| Veo 3.1 | 1080p | 35 | High |
| Kling 3.0 | 4K | 48 | Medium |
| Seedance 2.0 | 720p | 22 | Low |
Create an initial mask
Open Image to Video and upload the first frame. Draw a loose bounding box around the subject, then set the prompt to "subject only, transparent background." Run at 50 % strength so the model respects the original motion.
Refine with reference frames
Switch to Reference to Video. Upload three evenly spaced frames from the clip as reference images. Add the prompt "maintain exact subject silhouette across all frames" and set consistency weight to 0.85. This step usually finishes in 90 seconds and returns a 15-second sequence with consistent alpha.
Apply video-to-video cleanup
Feed the masked sequence into the Video to Video tool. Select the same model used earlier and add the negative prompt "background elements, motion blur on edges." Set frame count to 360 for a 15-second 24 fps output. The job consumes 48 credits with Kling 3.0.
Verify and iterate
Download the result and scrub frame-by-frame in any player. Check edges at 200 % zoom for halo artifacts. If stray pixels remain, return to the mask step and lower the strength slider by 10 points before re-running.
Export final matte
Once the matte passes inspection, export at the original 1080p resolution with alpha channel enabled. The file lands as a QuickTime ProRes 4444 sequence ready for the edit timeline.
- Upload the source clip to the dashboard and confirm 1080p 24 fps metadata.
- Choose Kling 3.0 on the video-to-video page and set output duration to 15 seconds.
- Generate the first mask using the image-to-video tool with a loose bounding box.
- Feed three reference frames into reference-to-video at 0.85 consistency.
- Run the full sequence through video-to-video with the negative prompt for background removal.
- Scrub the output at 200 % zoom and adjust strength if edge halos appear.
- Export the final matte as ProRes 4444 with alpha preserved.
- Import the matte into the edit and composite against the new background plate.
The finished 15-second clip now contains a clean subject layer that composites without spill or edge flicker. Repeat the exact sequence on Video to Video for the next project.