One 58-second vertical master that fits Shorts, Reels, and TikTok ads

A 58-second, 1080x1920 file with audio is inside every length line I read this week. YouTube Shorts allow up to 3 minutes and 1080p; Instagram does not recommend Reels over 3 minutes to new audiences; TikTok reservation and TopView accept 5-60 seconds; Google recommends Shorts ads under 60 seconds; and a Short under a minute avoids the over-one-minute Content ID block (read 2026-10-07). One Timeline 1.0 render makes it for $0.10.

It is not a replacement for platform previews, but it removes the length argument.

The check table

Sources: YouTube Shorts help, three-minute Shorts, Google Ads video specs, TikTok reservation, TopView, and Instagram Reels.

What still has to be true

Length is the easy part. TikTok's reservation pages also need audio, no watermarks, 500 MB or less, and 2,500 kbps or more. At 58 seconds, 2,500 kbps is at least 18.1 MB (2,500 x 58 / 8 = 18,125 kB, decimal), well under 500 MB. Instagram's aspect, frame-rate, and file rules were not readable for me, so check them in the app.

Render it

Timeline 1.0 defaults to 1080x1920 and MP4. Set audio.duration_seconds: 58, give it a voice or music spine so the file has audio, and cover the spine with video slots (coverage can stop at most 0.5 seconds before the end). output.fade_out_seconds takes 0-5 seconds if you want a soft end.

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: master-58s-001" \
  -d '{
    "audio": { "url": "https://media.sume.com/artifacts/artf_demo/vo.wav", "duration_seconds": 58 },
    "video": [
      { "source_url": "https://media.sume.com/artifacts/artf_demo/a.mp4", "start": 0, "duration": 29 },
      { "source_url": "https://media.sume.com/artifacts/artf_demo/b.mp4", "start": 29, "duration": 29 }
    ],
    "output": { "width": 1080, "height": 1920, "fade_out_seconds": 0.5 }
  }'

Verify with the probe

Run video inspect with frames: false. Expect duration_seconds near 58, width 1080, height 1920, has_audio true, and size_bytes times 8 over seconds above 2,500,000 bits per second. Poll the render per Jobs and results first.

If the bitrate falls short, you cannot set one in Sume; re-render with richer footage and probe again.

Where one master is not enough

A single file ignores platform differences you have not read: safe zones, captions placement, and aspect rules beyond those on the pages I fetched. Treat the 58-second master as the common length, then make a variant per destination for text placement.

Most Sume caption styles accept a design.placement.anchor_ratio override for where the caption line sits, and video-filter can dim or crop, so a per-platform variant is a short job. That keeps the picture the same and the overlays different.