YouTube Shorts speed tool: slow motion and timelapse, and Sume

YouTube's Shorts camera has a Speed tool that changes the speed of what you record, and Sume cannot do that to an existing clip: its docs list no speed or retime control. The video filter's allowlist explicitly excludes trim and setpts. For slow motion or a timelapse, set the speed in YouTube's tool or your editor, then bring the result to Sume for trimming, cropping or captions.

YouTube's side is from Enhance your Shorts and Create YouTube Shorts, read on 2026-10-02. The Sume side is from Video filter and Video trim.

What does the Speed tool do?

The Enhance your Shorts page lists Speed among the recording tools, alongside Timer for hands-free recording, Filters that can vary per segment, Effects, Green screen and Align. The pages I read do not state the available speed values, so check the tool on your own phone. Recording is segment based, with a progress bar showing each segment's length and undo and redo for clips.

Can Sume change a clip's speed?

No, based on the current docs. Video trim cuts a range and can conform output size and frame rate, with fps limited to 24, 25, 30 or 60; that conforms frame rate, it does not slow the clip. Video filter takes dim, crop and a filters-only graph from an allowlist covering tone, blur, geometry, fade and internal compositing, and the docs say trim and setpts are not on it. Audio and video retiming are not documented anywhere in Sume's media routes.

What should you do instead?

Pick the order by task. If you shot the clip yourself, apply Speed in the YouTube camera or in any editor with retiming, export the result as square or vertical and under 3 minutes, and upload it. If you need a clean cut afterwards, send the exported MP4 to video trim; if it is landscape, crop first with video filter, then trim, as in this post.

If you are generating the footage, you can ask for slow motion in a POST /v1/videos prompt, such as a slow-motion pour. The docs promise no speed control, so check the output before you rely on it.

curl -X POST https://api.sume.com/v1/video-trim \
  -H "Authorization: Bearer $SUME_API_KEY" \
  -H "Content-Type: application/json" \
  -H "Idempotency-Key: after-speed-trim-001" \
  -d '{
    "video_url": "https://media.sume.com/artifacts/artf_demo/sped.mp4",
    "start": 0,
    "duration": 45,
    "output": {"width": 1080, "height": 1920, "fps": 30}
  }'

Does speed change the Short's length limit?

The 3-minute limit applies to the finished video, so a timelapse that compresses 6 minutes of footage into 90 seconds is fine, and slow motion that stretches 2 minutes of footage past 3 is not. Check the exported duration, not the source length. Sume's probe-only video inspect is a free way to read it.