Luma Ray3.2 allows 16 keyframes; Sume offers first and last frame

Luma's Ray3.2 API page says Multi-Keyframe lets you set up to 16 keyframes inside a single clip. Sume does not list Luma. What Sume's video models accept is two frame positions, first_frame and last_frame, through the frame_images field of POST /v1/videos, so a 16-keyframe storyboard has to be built from several clips.

The rest of this post compares what the vendor page says with what Sume's documentation says, nothing more.

Control surface from each page

The Luma figures are from its API page read 2026-10-09; Sume's are from its video docs.

Building a longer sequence from two-frame clips

If you need a sequence that passes through several poses, chain clips: generate clip A from frame 1 to frame 2, clip B from frame 2 to frame 3, and so on. Each clip is its own job. With Wan 3.0 on Sume at 720p, four 5-second segments cost 4 x 5 x $0.125 = $2.50, and the joins are cuts you assemble yourself.

Sume's timeline render takes video slots and renders at $0.10 per output minute with a one-minute minimum, so assembling the four segments adds $0.10 (the sheet also lists a $0.02 compose job).

When to choose which

Choose Luma if the single-clip control of many keyframes, HDR or EXR delivery is the requirement, since Sume lists none of those. Choose Sume if you want video next to audio, captions and timeline tools under one balance and two-frame control is enough. Check supported_frame_images on each model via GET /v1/videos/models before you write the request.

Sequence cost on Sume

The following figures use the same list prices as the tables above.

• A 20-second sequence from four 5-second Wan 3.0 clips at 720p is 20 x $0.125 = $2.50 for the clips.
• The same sequence on MiniMax H3 at 768p is 20 x $0.075 = $1.50, with 5 seconds being H3's minimum clip.
• Sume has no multi-keyframe field, so a plan that needs 16 poses in one clip is a reason to use Luma directly.
• Luma's page lists no per-second price in the content I retrieved, so there is no price comparison here.

Limits of this comparison

There is a second way to get more control from a two-frame model: shorten the clips. Short clips between two chosen frames give you more say over where the motion goes. At Wan 3.0's 720p rate of $0.125 per second, a 16-pose sequence at 2 seconds per pose (the model's minimum) is 15 transitions x 2 s x $0.125 = $3.75. That is a rough estimate for a plan, not a claim of equivalent output to a native 16-keyframe clip.