How to add cinematic letterbox mattes to your videos

What a matte should do

A good letterbox matte is not just black bars. It should preserve the center image, keep alpha transparency, fit the delivery canvas exactly, and stay readable after social compression.

• Use a transparent PNG when the frame needs to sit above footage.
• Use clean black bars for narrative, documentary, music video, and trailer edits.
• Use rounded or softened corners only when the visual language is social, UI, or creator-pack oriented.

Generate the overlay

Open the FrameGen tool, choose Letterbox, then pick the delivery canvas before changing border thickness. This keeps the matte aligned to the final export rather than the source clip.

Place it in your timeline

Import the PNG into your editor and place it on the top video track. Stretch it to the full length of the edit, then lock the track so cuts and transitions do not move the matte by accident.

• Premiere Pro / DaVinci Resolve / Final Cut: place the PNG above footage at 100% scale.
• CapCut / VN / InShot: use Overlay, Sticker, or Import layer, then set it full screen.
• OBS or livestream workflows: add the PNG as an image source above camera or capture layers.

Check before export

Before rendering, scrub the whole timeline at full frame. Check titles, faces, captions, and platform UI safe zones. The matte should guide the eye without hiding important information.

• Do not scale the exported PNG unevenly; regenerate the exact size instead.
• Avoid putting captions under the matte unless the bars are intentionally used as title space.
• Export a short test clip before rendering the full project.