TikTok title 2200 UTF-16 runes vs burned-in captions from Sume

The two are unrelated fields: the post title is text you send to TikTok ("The maximum length is 2200 in UTF-16 runes"), while burned-in captions become pixels inside the video. Sume's POST /v1/video-captions burns exactly the cues text you pass, so your on-screen words are never limited by, or copied from, the title.

What does the title limit count?

TikTok states the limit in UTF-16 runes. Measure the length in your own code with the same unit before you send the title.

How do I burn exact words?

Pass cues (or segments) with text, start and end in seconds. That skips speech-to-text and burns exactly that copy at those times. This is also the route for silent clips, which otherwise fail as caption_no_speech. script_text, words, cues and segments are mutually exclusive.

curl -X POST https://api.sume.com/v1/video-captions \
  -H "Authorization: Bearer $SUME_API_KEY" \
  -H "Content-Type: application/json" \
  -H "Idempotency-Key: caption-cues-001" \
  -d '{
    "video_url": "https://media.sume.com/artifacts/artf_demo/clean.mp4",
    "cues": [
      { "text": "Three steps", "start": 0, "end": 2 },
      { "text": "Step one", "start": 2, "end": 4 }
    ]
  }'

Can I upload an SRT file?

No. The docs say SRT uploads are unsupported; pass phrase-level text as cues or segments. Convert an SRT into cues in your own code. A standalone caption job costs $0.20 for videos up to 60 seconds under the current fixed estimate; confirm the live price in GET /v1/catalog.

What do I still do myself?

Write the post title and send it in the Direct Post call. Sume does not post to TikTok or count runes. If you flag AI-generated content, TikTok's reference describes a separate is_aigc field that is set in that same call.

When should I burn captions at all?

Burn them when the words must be visible whatever the viewer's settings, for example a silent hook or a translated line. Keep them out of the title when the title has its own job. The caption styles are named in the docs (slam, punch, tiktok-green, korean-ad), and design.placement.anchor_ratio sets the line centre as a fraction of frame height.