Keep a sub-3-minute video out of YouTube Shorts: render it 16:9

YouTube's Shorts help page says square or vertical videos up to 3 minutes are Shorts, and that to keep a video long-form you should use a wider aspect ratio such as 16:9 (read 2026-10-04). If your 90-second tutorial must land as a regular upload, the ratio is the lever.

Sume's Timeline defaults to 1080 by 1920, which is vertical, so a default render of any length up to 3 minutes can be classified as a Short. Override it.

Set width and height

Timeline 1.0 accepts output.width and output.height as even integers from 256 to 2160. 1920 is below 2160 on the long side, so 1920 by 1080 works. Use the plan endpoint first; it compiles the program and returns an estimated cost without creating a job.

import os
import requests

body = {
    "audio": {"mode": "silence", "duration_seconds": 90},
    "video": [{
        "source_url": os.environ["CLIP_URL"],
        "start": 0,
        "duration": 90,
        "fit": "cover",
    }],
    "output": {"width": 1920, "height": 1080},
}
r = requests.post(
    "https://api.sume.com/v1/timeline-1.0/plan",
    headers={"Authorization": f"Bearer {os.environ['SUME_API_KEY']}"},
    json=body,
)
print(r.status_code, r.json())

If the source is vertical

A 9:16 source in a 16:9 frame needs a fit rule. cover crops, contain letterboxes, blur fills the sides with a blurred copy and stretch distorts. A render at $0.10 per output minute rounds up, so 90 seconds is 2 minutes, or $0.20.

If the AI clip itself should be wide, generate it 16:9. kling-3, seedance-2 and wan-3.0 all list 16:9. Shorts rules change, so reread the help page before a launch.