Seedance 2.5 1080p ratio 1920:1080 on Sume: resolution + aspect_ratio

On Sume you do not send 1920:1080. Send resolution: "1080p" and aspect_ratio: "16:9" (or 9:16 for vertical) to seedance-2.5, which accepts 4–30 seconds at 480p, 720p and 1080p. The pixel-pair size field is rejected on v1.

Runway's side is from its Dev API changelog; Sume's side is from the video generation docs, both read 2026-10-01.

What did Runway change for Seedance 2.5?

The changelog entry dated August 15, 2026 says Seedance 2.5 (seedance2_5) now supports 1080p on text-to-video, image-to-video and video-to-video. You pass a 1080p ratio such as 1920:1080 (16:9) or 1080:1920 (9:16). It also says 4K stays on Seedance 2.0.

How do the two request shapes map?

Sume splits what Runway packs into one string. The docs say each model advertises the resolutions it accepts in supported_resolutions and the ratios in supported_aspect_ratios.

Why does size fail on Sume?

The docs state that every v1 model reports supported_sizes: null, so size returns 400 unsupported_parameter. Use resolution plus aspect_ratio. Do not translate 1920:1080 into size: "1920x1080".

How do I check what a model accepts before I send?

Read the model list and look at supported_resolutions and supported_aspect_ratios for the id. If you plan to review at low resolution first, see draft at 480p, then 1080p.

const res = await fetch("https://api.sume.com/v1/videos/models", {
  headers: { Authorization: "Bearer " + process.env.SUME_API_KEY },
});
console.log(await res.json());

What should I do next?

Replace any ratio-string parsing with a lookup of the two fields, and read the model list at startup instead of hard-coding which resolutions exist. Reservations are made at provider list × 1.25 on submit, so a 1080p request holds more than a 480p one.