Use the start and end frames to generate smooth transitions that morph between two images. Common use cases include animated title cards between sections, scene transitions, creative reveals (e.g., sketch → photorealistic), and before/after demonstrations.
Start and end frames are an optional parameter for creating AI video in Descript, available for select models. If you're new to generating video, start with our guide: Generate AI video.
This article covers:
How to use start and end frames
Before getting started, you'll need a starting image and an ending image. You can generate them in Descript, import your own, or take a snapshot of your current canvas.
- Add your starting image: Import your starting image and add it to your scene editor as a layer. (You can also generate an image directly in Descript.)
- Select your starting image in the scene editor.
- Click the Underlord tab in the hover toolbar, then select Turn into video. The Generate media panel will expand, and the image will automatically be added as the Start Frame.
- Select the End frame button, then click + Add image.
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Describe the transition: Write a short prompt describing how the transition should happen. Here's the prompt used in the example video:
“The wig magically materializes on the pig’s head, starting as a subtle shimmer and then fully forming into the glamorous hairstyle. The pig stays perfectly still like a professional model while the wig and dress appear and settle into place. Smooth, polished transformation with consistent lighting.”
- Click Generate, then hang tight while your video is created.
Once it’s ready, hover over the thumbnail in the sidebar to review your video. If you like it, replace the selected image layer in your composition.
Tips for better transitions
Image setup
- Match composition: Use images with similar framing (angle, subject size, and position).
- Keep lighting consistent: Similar backgrounds and lighting help the morph feel natural.
Writing your prompt
- Describe the transformation: Focus on how elements change, not just the end state. Instead of: “The drawing becomes realistic.” Try: “Crayon strokes smooth into metallic panels. Flat colors gain depth and shine. Wobbly lines straighten into precise edges.”
- Call out constants: Specify what should stay fixed (e.g., “maintain the position,” “keep lighting consistent”).
- Set pacing: Use words like “gradually,” “smoothly,” or “sudden pop” to control speed and feel.
- End with tone: Add a style note such as “smooth and professional,” “magical and inspiring,” or “dramatic and cinematic.”