Captions and text overlays
Genyad burns captions into every variation using the word-level timings its voiceover synthesis returns, and places headline overlays inside each platform's safe zone. Both are styleable from a typography catalogue rather than a single default, because the caption style is itself a variable worth testing.
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Why burned-in captions instead of platform captions
Platform auto-captions are optional, styled by the platform, and frequently off. A large share of feed impressions are watched muted, so the text layer is doing the selling. Burned-in captions are part of the video file, which means they render the same everywhere, including in an ad preview and in a downloaded file a client reviews.
- Word-synced, from the same timings the voice synthesis produced
- Styled per variation, so caption treatment can be A/B tested like a hook
- Kept inside the safe zone so no line is hidden behind a platform UI overlay
Safe zones by placement
| Placement | Aspect | Keep text clear of |
|---|---|---|
| Reels and TikTok feed | 9:16 | Top ~14% and bottom ~20% |
| Stories | 9:16 | Top ~14% and bottom ~20% |
| Facebook and Instagram feed | 4:5 | Bottom ~10%, headline area |
| Feed square | 1:1 | Bottom ~10% |
| YouTube in-stream | 16:9 | Bottom-right controls |
These are working margins, not published constants: platforms move their UI. The point of enforcing them at render time is that a variation is never rejected in review because the offer was sitting under a Shop Now button.
Typography as a test variable
Caption treatment changes measured performance more than most teams expect, because it changes how much of the message survives a muted, half-second look. Genyad ships a catalogue of caption styles with real fallbacks per family, so a style choice renders the same on the render server as it does in the preview.
Frequently asked questions
Are captions generated automatically?
Yes, from the voiceover's word-level timing. You can edit the text and restyle it, and the sync is preserved.
Can I add my own fonts?
The catalogue covers the common paid-social styles. Brand font uploads are handled on Enterprise.
Do overlays adapt when I export a different aspect ratio?
Yes. Each export respects that placement's safe zone rather than scaling one layout to every ratio.
Can I turn captions off for one variation?
Yes, per variation, which also makes caption-versus-no-caption a legitimate thing to test.