Previously on: add a recap to a YouTube Shorts series episode

To add a Previously-on recap to a Shorts series episode, join the last few seconds of the previous episode to the front of the new one in a single Timeline 1.0 render. Then check the total: the recap counts toward the 180-second limit for a Shorts series episode, and it can push the price into the next billed minute.

Why add a recap

YouTube's series page says a Shorts series playlist may hold only Shorts, each portrait or square and at most 180 seconds, and that episode numbers follow the publish date (YouTube Help). Viewers who land on an episode from their feed get a watch-series button and swipe between episodes (YouTube Help). A recap helps the viewer who came in at episode 4 without seeing episode 3.

The render body

Timeline 1.0 needs one audio spine. Detach the audio of both episodes once ($0.01 each), then use audio.parts[] to splice the recap audio in front of the episode audio. Video slots can reuse the full episode files with source_in, so no trim job is needed. The body below recaps the final 4 seconds of a 60-second episode 3 in front of a 56-second episode 4. The file URLs are placeholders for your own imported media.sume.com artifacts.

{
  "audio": {
    "duration_seconds": 60,
    "parts": [
      { "url": "https://media.sume.com/artifacts/artf_ep3/audio.wav", "source_in": 56, "duration": 4 },
      { "url": "https://media.sume.com/artifacts/artf_ep4/audio.wav", "duration": 56 }
    ]
  },
  "video": [
    { "source_url": "https://media.sume.com/artifacts/artf_ep3/ep3.mp4", "start": 0, "source_in": 56, "duration": 4 },
    { "source_url": "https://media.sume.com/artifacts/artf_ep4/ep4.mp4", "start": 4, "source_in": 0, "duration": 56 }
  ]
}

Cost and the 180-second check

Send it to POST /v1/timeline-1.0/render with an Idempotency-Key. Run POST /v1/timeline-1.0/plan first to read billable_minutes without a charge. The rate is $0.10 per ceil(output minute), so the recap can double the bill on an episode that was just under a minute.

Add the two $0.01 detach jobs to the price in the table. The last row is not a Short episode at all.

Publish order

Publish in order. Because YouTube numbers episodes by publish date, upload the recap version of episode 4 after episode 3 and not before it. Keep the recap short and the same on every episode so it reads as a format, and pair it with the season trailer pattern if you also want a cold open.