YouTube A/B testing three cuts: render the variants by API

YouTube's Made on YouTube post says Studio now supports video A/B testing of up to three different cuts. Sume does not run the test. It can make the cuts: trim one source video three ways with POST /v1/video-trim, or assemble three orderings with Timeline 1.0, then upload each to Studio yourself.

Prices and limits below are from the Sume Video trim and Timeline docs, read 2026-10-01.

How do I make three cuts of one source?

Import the source once (POST /v1/media-imports), then submit one trim per variant with a different start and end or duration. Each returns a new artf_ MP4 and leaves the source alone. The source can be up to 1800 s and each output up to 900 s. If a variant needs reordering rather than a different range, build it as a Timeline with its own video[] slots.

const base = "https://api.sume.com/v1/video-trim";
const ranges = [
  { start: 0, duration: 45 },
  { start: 5, duration: 40 },
  { start: 12, duration: 33 },
];
for (const [i, r] of ranges.entries()) {
  const res = await fetch(base, {
    method: "POST",
    headers: {
      Authorization: "Bearer " + process.env.SUME_API_KEY,
      "Content-Type": "application/json",
      "Idempotency-Key": "cut-" + i,
    },
    body: JSON.stringify({ video_url: process.env.SOURCE_URL, ...r }),
  });
  console.log(i, (await res.json()).request_id);
}

What do the three variants cost?

Trim is billed per job, so three cuts are three jobs. A Timeline render is billed per output minute, rounded up.

Can I check a Timeline variant before paying?

Yes. POST /v1/timeline-1.0/plan is unbilled and returns billable_minutes; see the plan preflight.

What does Sume not do here?

It does not publish to YouTube, create the Studio test, or tell you which cut holds attention; the YouTube post describes that part of Studio. Keep the three outputs distinct in what they change, such as the opening seconds, so the test measures one thing.