Shorts series episode one: check four opening frames in two seconds

Short answer

YouTube's series page says a watch series button leads viewers into a series feed, so episode one is where a new viewer starts. Check its first two seconds with four stills, at 0, 0.5, 1 and 2 seconds, using video inspect, which defaults to a synchronous call that returns stills with the probe.

Why episode one gets the extra check

The Shorts series help page describes a watch series button that leads into a series feed, and says serial series play oldest first while non-serial series show newest first (read 2026-10-05). YouTube's Sept 23, 2026 post describes sequential playback across web, mobile and TV (read 2026-10-05). In a serial series, the oldest episode is first, so for most viewers the first thing they see is the opening of episode one. If the frame at 0 is black or a title card with no subject, the series loses viewers before the story starts.

The four-frame check

The timestamps are explicit, so each still is the accurate frame at that instant.

The call

POST /v1/video-inspect accepts frames with an at list of 1 to 24 instants and a max_edge from 64 to 2160, which defaults to 768. The call needs a media.sume.com source and an Idempotency-Key. By default it waits up to 30 seconds and answers 200 with the result, or 202 with a job to poll.

import json, os, urllib.request

key = os.environ.get("SUME_API_KEY", "")
if not key:
    raise SystemExit("set SUME_API_KEY")
body = {
    "video_url": "https://media.sume.com/artifacts/artf_demo/ep1.mp4",
    "frames": {"at": [0, 0.5, 1, 2], "max_edge": 540},
}
req = urllib.request.Request(
    "https://api.sume.com/v1/video-inspect",
    data=json.dumps(body).encode(),
    headers={"Authorization": "Bearer " + key,
             "Content-Type": "application/json",
             "Idempotency-Key": "ep1-open-check"},
)
print(json.load(urllib.request.urlopen(req)))

Reading the result

The resource contains a probe and a frames list of t, url, width and height, with stills as durable media.sume.com images. Open the four URLs side by side. If the first frame is black, trim a few tenths off the head with video trim or move the in-point on the timeline slot. The probe also reports has_audio, so you can tell a silent clip from a clip with sound before you judge the opening.

Run the same check on every episode, since a viewer who lands on episode five from elsewhere meets that opening first. For episode one, also look at the thumbnail frame you chose, because the series view uses a custom thumbnail.

If you are making the episode with Sume, the usual fixes are small. A black first frame comes from a clip with a fade-in baked into the source or from a timeline output fade, since output.fade_in_seconds can be set from 0 to 5 seconds. Set it to 0 for episode one if you want the first frame to be the hook. A title card burned into the first slot is another cause; move it to the second.

Repeat the four-frame check after any re-render, since a change to the first slot changes what the first frame is.