Runway Ruby SDR-to-HDR API: 30-second limit, 4096 px, 20 credits/s

Runway's Ruby model converts an SDR video into HDR through /v1/video_to_hdr, accepts at most 30 seconds and under 4096 pixels per side, and costs 20 credits per second, or 40 above 4 megapixels. Sume's video endpoint returns an MP4 download and documents no HDR option, so the usual route is to generate on Sume, trim, and grade with Ruby afterwards.

Runway's side is from its API changelog and pricing page, both read on 2026-10-03. Sume's side is from the video generation docs and Video trim.

What are Ruby's input limits?

The August 20 changelog entry gives three limits: the source must be SDR, it can run at most 30 seconds, and each side must be under 4096 pixels. Outputs are HDR10 by default, or HLG, HDR ProRes or an OpenEXR sequence, with colorimetry and provenance metadata alongside.

A September 11 entry adds that Ruby preserves the alpha channel of a source video. ProRes deliveries use 4444 and EXR deliveries write alpha as the A channel; the HDR10 and HLG outputs carry none.

What does a Ruby conversion cost in dollars?

Runway's pricing page lists Ruby at 20 credits per second, and 40 credits per second for oversized sources above 4 megapixels. At $0.01 per credit, the worked examples below follow directly.

What does Sume hand Ruby?

The Sume video docs download a finished job with GET /v1/videos/{jobId}/content and save it as video.mp4. Nothing in them lists HDR, ProRes, EXR or alpha, so treat a Sume clip as SDR. That makes it a valid Ruby input, as long as it meets Runway's size rule: confirm the resolution you asked for stays under 4096 pixels per side, which every 480p to 1080p result does.

The 30-second ceiling is the part to plan around. A Sume model can return up to 30 seconds (seedance-2.5 accepts 4 to 30 seconds), so a long clip sits right at Ruby's limit. Anything longer needs cutting first, and Video trim does that: it takes one Sume-hosted clip and a range and returns a new MP4 of only that range, leaving the source untouched.

What does Sume not do here?

Sume does not convert SDR to HDR, does not export ProRes or EXR, and does not carry alpha through a video job. If a delivery spec asks for HDR10, HLG or a scene-referred sequence, the grading step happens in Runway or another tool. The rest of the pipeline, the generation and the trim, stays on Sume's list-times-1.25 billing.

The sibling posts on Runway's alpha channel and ProRes 4444 and what Sume outputs for HDR and EXR cover the delivery formats; this one is only about the limits to check before you upload.

How would the whole pipeline look?

Submit the video job to Sume with a duration of 30 seconds or less, poll it, download the MP4, and upload it to Runway as the Ruby input. If you generated more than 30 seconds, cut a range out with video trim first. Each step is a separate hosted call, and Sume's job status endpoints show where a run stands.

Budget both halves. Sume reserves the provider list price times 1.25 when you submit, and the final usage.cost is the amount billed. Runway's half is the credit table above. A 10-second 1080p clip graded to HDR10 adds $2.00 on Runway's side, regardless of which model made the clip.

One last check before committing: Ruby only takes SDR sources. A Sume result is documented as an ordinary MP4 download, but if you have run it through an earlier HDR tool, convert back first, because Runway lists SDR as the only accepted source type.