Kling 4.0 or Seedance 2.5 for a 30-second AI video today?
Both advertise 30 seconds. Only one has a callable id on Sume today. A spec-by-spec read of the vendor pages and what you can actually request.
Which should you pick for a 30-second AI video today, Kling 4.0 or Seedance 2.5? If you need to call an API this week, Seedance 2.5, because Sume's video router lists seedance-2.5 at 4 to 30 seconds. The Kling 4.0 page describes a 3 to 30 second native range but gives no API, pricing or availability beyond an early access phase, and Kling 4.0 is not in Sume's catalog.
What the two vendor pages promise
The Kling 4.0 announcement lists native 3 to 30 second output, up to 10 keyframes, 4K, 21:9, two-channel stereo, prompts up to 8,000 tokens, and 10-bit HDR at 1080p and 4K as "coming soon". It says early access began September 28 with a full launch in October 2026.
The Seed announcement lists up to 30 seconds per generation with multi-round extension, plus timestamp-level editing and green-screen background replacement.
| Item | Kling 4.0 | Seedance 2.5 |
|---|---|---|
| Length per generation | 3-30 s | Up to 30 s, extendable |
| Reference mix | Up to 15 assets, 10 images, 5 videos | Up to 30 images, 10 videos, 10 audio |
| Resolution on vendor page | Up to 4K | Not stated |
| Callable on Sume | No | Yes, seedance-2.5, 480p-1080p |
| API stated on vendor page | None | Coming soon via BytePlus ModelArk |
Where the answer flips
If your clip needs 4K or 21:9 delivery straight from the model, Kling 4.0 is the only one of the two that claims it, and you will have to wait for broader access. If you need audio references, Seedance 2.5 takes them on Sume and in the Seed announcement, while the Kling page describes voice references.
What Kling you can run now
Sume's kling-3 row runs 4 to 15 seconds at 720p and 1080p, with 16:9, 9:16 and 1:1, so it cannot do a single 30 second pass. For a 30 second piece on Kling 3, cut two 15 second clips and join them on a timeline. That is a different product from a native 30 second render, and continuity between the two clips is on you.
A decision list
Vendor pages describe capabilities, not guarantees about prompt adherence or quality, so this post compares specifications only and has no head-to-head test. Before a 30 second job, render a short pass at 480p to check the idea, then render the full-length clip at the resolution you need. Long clips cost more per request, so the cheap pass is worth the extra minute.
- You must call an API this week: Seedance 2.5 on Sume, billed at the list price times 1.25.
- You need 4K from the model itself: watch for Kling 4.0 access, and note the page says full launch is October 2026.
- You need audio references: Seedance 2.5 takes image, video and audio references on Sume.
- You need native 21:9: both list it, Seedance 2.5 among its aspect ratios on Sume and Kling 4.0 on its page.
Sources
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