Synthesia test videos are free; Sume previews first frames instead

Synthesia's Create a video endpoint has a test boolean, default false, and its reference says test videos are free and not counted toward your quota. Sume has no equivalent flag on the talking-video route. What it offers instead is a first-frame stage: an avatar video preview renders stills, you approve them, and only then do you call generate-video on the preview id. The two protect your budget in different ways.

Synthesia facts below come from its create-video reference and pricing page, read on 2026-10-04. Sume facts come from Generate avatar video and the preview page.

What a Synthesia test video gives you

A test render goes through the same pipeline as a real one, so you see motion, voice and timing. The reference notes that test videos carry a watermark overlay. That makes the flag a good way to check script wiring and layout in CI without spending quota, but the artifact is not something you can ship.

What the Sume preview stage gives you

A preview takes the same body as the talking-video route: exactly one of script or video_inputs, plus optional product_image, scene, quality, aspect_ratio, title and captions. The response carries an avatar_video_preview_id, and you poll the job like any other generation.

Because the still is reused, the final render keeps the framing you approved. Preview stills are tier-independent, so you can approve once and choose standard, plus or max only when you call generate-video. Structural changes such as a new script need a new preview.

Which draft fits which risk

Use a watermarked full render when the risk is timing, pacing or voice. Use stills when the risk is composition: wrong scene, wrong product placement, a crop that hides the face. Sume's stage cannot tell you whether a 40-second script feels slow, so read the script aloud and keep it inside the 4 to 60 second window the docs describe.

• Run a preview for every new scene prompt or product image.
• Skip it for repeat scripts on a scene you already approved.
• Store the preview id with your own record so a reviewer can approve later without re-rendering.

A minimal Sume call

The order is preview, poll, read the resource, then generate. Read resource_status for readiness and job_status for polling, as the docs recommend over the legacy status field.

curl -X POST https://api.sume.com/v1/avatar-video-previews \
  -H "Authorization: Bearer $SUME_API_KEY" \
  -H "Content-Type: application/json" \
  -H "Idempotency-Key: preview-launch-001" \
  -d '{"avatar_handle":"product_host","script":"Meet the new travel mug.","aspect_ratio":"9:16"}'

Bottom line

If your workflow depends on a free full-motion draft, Synthesia's test flag does that and Sume does not. If you need an approval gate before paying for the final render, Sume's preview stage is built for it.