How to stop YouTube from making my video a Short

Upload the video in a wider aspect ratio such as 16:9. YouTube's help page says that is how you keep content from being classified as a Short: a square or vertical video up to three minutes long is categorized as a Short, a widescreen one is not.

The rule comes from YouTube Help, Shorts up to three minutes, read 2026-09-29. The Sume part is from the Timeline 1.0 docs.

What makes YouTube treat a video as a Short?

Two things on the page: the shape and the length. Videos with a square or vertical aspect ratio and a length of up to three minutes are categorized as Shorts, for videos uploaded on or after the dates below. The page gives one date for standard YouTube channels and another for Official Artist Channels.

Can I keep a vertical video out of Shorts?

The page names one method: use a wider aspect ratio such as 16:9 for long-form videos. It does not describe a switch that turns the Short classification off for a vertical video. If your source is vertical, plan a widescreen version before you upload.

Length alone is not the lever on this page. The three-minute limit only matters for square and vertical videos.

Music channels have their own date. For Official Artists Channels and channels linked to a music Content Owner, videos that are square or taller in aspect ratio, over one minute long and uploaded before December 8, 2025 continue to be treated as long-form. The same kind of video uploaded on or after that date is classified as a Short.

How do I render a 16:9 video with Sume?

Sume's Timeline 1.0 renders vertical 1080x1920 by default, so a widescreen file needs an explicit output. Width and height are even integers from 256 to 2160, so 1920x1080 is allowed. Inputs must already be this workspace's media.sume.com files, and the call needs an Idempotency-Key. In current code a Timeline render takes sound only from its audio track and optional soundtrack, so a source clip's own audio is dropped.

For generated clips, Video generation accepts aspect_ratio: "16:9", and each model advertises the ratios it accepts in supported_aspect_ratios. Check that list before you pin a ratio.

curl -X POST https://api.sume.com/v1/timeline-1.0/render \
  -H "Authorization: Bearer $SUME_API_KEY" \
  -H "Content-Type: application/json" \
  -H "Idempotency-Key: widescreen-001" \
  -d '{
    "audio": {
      "url": "https://media.sume.com/artifacts/artf_demo/voice.wav",
      "duration_seconds": 30
    },
    "video": [
      { "source_url": "https://media.sume.com/artifacts/artf_demo/a.mp4", "start": 0, "duration": 30 }
    ],
    "output": { "width": 1920, "height": 1080, "fps": 30 }
  }'

What are the limits of this answer?

This is what one YouTube help page says on the date above; YouTube can change it. It does not cover recommendations or which surface a video appears on. For the reverse case, making a proper Short, see YouTube Shorts video specs; for long-form settings, see YouTube video size and upload settings.