SB video up to 45 s needs two Sume clips

A third-party spec page (alladspecs.com), read on 2026-10-03, says Amazon Sponsored Brands video runs up to 45 seconds, up to 500 MB, in 16:9 landscape. Sume's seedance-2.5 accepts 4 to 30 seconds per clip, so a 45 second ad is two clips joined with Timeline 1.0.

The Amazon numbers

These come from a third-party page, not Amazon, so confirm them in Amazon Ads documentation before you build. The page recommends 6 to 20 seconds, and lists 1920x1080 as the main size.

Why two clips

Limits on Sume are per model. seedance-2.5 accepts 4 to 30 seconds at 480p, 720p and 1080p; seedance-2 and most other catalog models top out at 15 seconds. So 45 seconds does not fit in one generation. Two clips of 23 and 22 seconds make 45.

Generate both, then join

Submit two POST /v1/videos jobs with distinct Idempotency-Key values, and set aspect_ratio to 16:9 on both since the page lists landscape. Download each, or take the Sume artifact URL from the result.

curl -X POST https://api.sume.com/v1/videos \
  -H "Authorization: Bearer $SUME_API_KEY" \
  -H "Content-Type: application/json" \
  -H "Idempotency-Key: sb-ad-part-1" \
  -d '{
    "model": "seedance-2.5",
    "prompt": "Part 1: a runner laces up at dawn, product close-up",
    "aspect_ratio": "16:9",
    "resolution": "1080p",
    "duration": 23
  }'

Timeline 1.0 takes one audio spine plus ordered video[] slots and returns one MP4. audio.duration_seconds is required and runs from 1 to 1800; supply audio.url, or audio.mode: "silence". Each slot takes a source_url, start and duration, and a slot can carry a transition. Every URL must be a media.sume.com artifact or asset. Run POST /v1/timeline-1.0/plan first; it is unbilled and returns duration_seconds so you can confirm the total is 45 or under.

Check the result

Read duration_seconds from the timeline result and check the file size on disk against the 500 MB figure. The join point is where a mismatch shows, so match the end of clip one to the start of clip two with frame_images or a short transition.