Burning Korean captions: why a Latin style returns a 400 on Sume

If your Short speaks Korean, do not pick slam, punch or tiktok-green. The Sume captions docs say those three draw in Latin display faces with no Hangul glyphs, so Korean copy sent to them returns 400 caption_hangul_text_latin_style. Sume rejects it on purpose: the docs argue a style you did not choose is worse than an error.

Which style when

• Omit style and the wording decides: slam for Latin text, black-outline for Korean.
• korean-ad is the CapCut-style Hangul karaoke look: one short phrase at a time, lower third. Pair it with language: ko.
• black-outline is described as the safe default: white fill on a thick black outline, mid-frame.
• Naming a Hangul font with a Latin style returns 400 caption_font_requires_hangul_style.

Cost and silence

Each accepted standalone caption job is $0.20 for videos up to 60 seconds under the current fixed estimate; confirm live in GET /v1/catalog. Speech-to-captions needs audible speech: a silent clip fails as caption_no_speech. For silent clips, send your own words, cues or segments with start and end seconds and no speech-to-text runs.

Restyle without paying for a second transcript

To try another look, pass source_caption_id instead of video_url. Sume reuses the source video and the word timings it already has, so no second speech-to-text runs. Billing is unchanged, because a restyle is still a render. If you are unsure which of two styles reads better on a phone, restyle once rather than guessing.

Why 60 seconds is the planning number

YouTube's Shorts guidelines say Shorts creation tools allow up to 3 minutes. The fixed $0.20 caption estimate on Sume covers up to 60 seconds, so check the live catalog before captioning anything longer.

Request

curl -X POST https://api.sume.com/v1/video-captions \
  -H "Authorization: Bearer $SUME_API_KEY" \
  -H "Content-Type: application/json" \
  -H "Idempotency-Key: ko-short-1" \
  -d '{"video_url":"https://media.sume.com/artifacts/example/clean.mp4","style":"korean-ad","language":"ko"}'