Problem
Open captions burned into a master are cropped at the bottom in a 9:16 derivative, leaving words partially hidden behind platform interface controls.
Solution
Root Cause / Diagnostic:
Exporting burned-in open captions positioned for standard video rasters without accounting for vertical UI margins causes native platform controls (titles, audio attributions, engagement buttons) to occlude bottom text lines. In 9:16 environments, platform UI footprints occupy the bottom 20–25% (roughly 380–480px on a 1080x1920 raster) of active display space. When a horizontal master is simply cropped or scaled down, baked-in captions positioned in traditional broadcast lower-third zones inevitably collide with these interactive overlays.
Actionable Fix:
1. Configure custom safe-zone guidelines in your NLE (Premiere Pro, DaVinci Resolve, or Final Cut) setting a bottom margin offset of at least 480 pixels (25% from bottom) on a 1080x1920 timeline.
2. Reposition burned caption tracks into the vertical safe band between Y=720px and Y=1440px to ensure complete clearance from UI overlays.
3. Test layout accuracy using a transparent PNG platform UI overlay template across TikTok, YouTube Shorts, and Instagram Reels before finalizing render.
Pro Tip:
Generate separate vertical export presets with dedicated graphic subtitle tracks rather than burning subtitles into intermediate master files.
Exporting burned-in open captions positioned for standard video rasters without accounting for vertical UI margins causes native platform controls (titles, audio attributions, engagement buttons) to occlude bottom text lines. In 9:16 environments, platform UI footprints occupy the bottom 20–25% (roughly 380–480px on a 1080x1920 raster) of active display space. When a horizontal master is simply cropped or scaled down, baked-in captions positioned in traditional broadcast lower-third zones inevitably collide with these interactive overlays.
Actionable Fix:
1. Configure custom safe-zone guidelines in your NLE (Premiere Pro, DaVinci Resolve, or Final Cut) setting a bottom margin offset of at least 480 pixels (25% from bottom) on a 1080x1920 timeline.
2. Reposition burned caption tracks into the vertical safe band between Y=720px and Y=1440px to ensure complete clearance from UI overlays.
3. Test layout accuracy using a transparent PNG platform UI overlay template across TikTok, YouTube Shorts, and Instagram Reels before finalizing render.
Pro Tip:
Generate separate vertical export presets with dedicated graphic subtitle tracks rather than burning subtitles into intermediate master files.