Render a vertical 1080x1920 video from clips with an API

A POST /v1/timeline-1.0/render already outputs a vertical 1080x1920 MP4 unless you say otherwise, so for a Reels, Shorts or TikTok cut you can leave output out. Set output.width and output.height (even integers from 256 to 2160) and output.fps (24, 25, 30 or 60) only when you need a different frame.

Details are from Timeline 1.0, read 2026-09-29. Platform upload specs change, so check the platform's own page for the current limits.

How do clips that are not vertical fit the frame?

Each video[] slot has a fit: cover (default) crops to fill, contain letterboxes, stretch distorts, and blur fills the empty area with a blurred version of the clip. A landscape clip in a vertical frame is the classic case for blur.

{
  "audio": { "mode": "silence", "duration_seconds": 8 },
  "output": { "width": 1080, "height": 1920, "fps": 30 },
  "video": [
    { "source_url": "https://media.sume.com/artifacts/artf_demo/wide.mp4",
      "start": 0, "duration": 8, "fit": "blur" }
  ]
}

What happens to frame rate?

Omit output.fps and the render runs at the rate the sources already use (the longest video sources decide; stills have none; 30 only when nothing has one). A rate that differs from a source's is met by repeating or dropping frames, which can judder on motion, and Sume reports it as the output_fps_resamples_sources warning.

What are the output options?

What if I need a still above a clip?

That is a different job: compose a still and a video into one shot first, set its output.width and output.height to match this render so it is not rescaled twice, then use the result as a slot. Price: $0.10 per output minute.

How do I render landscape or square instead?

Set both sides in output. The docs give the same range for each, even integers from 256 to 2160, so 1920x1080 and 1080x1080 are both valid, while a 3840 side is outside the range.

{
  "audio": { "mode": "silence", "duration_seconds": 8 },
  "output": { "width": 1920, "height": 1080, "fps": 30 },
  "video": [
    { "source_url": "https://media.sume.com/artifacts/artf_demo/wide.mp4",
      "start": 0, "duration": 8 }
  ]
}