Keep a whole 16:9 shot in 9:16: blur fill instead of cropping

A 16:9 to 9:16 crop throws away about 68% of the width, so wide shots with two subjects or a product and a hand do not survive it. The alternative in Sume Timeline is fit: blur, which keeps the whole 16:9 frame and fills the rest of the 1080x1920 canvas with a blurred version of it.

Luma lists a Reframe feature for Ray 3.2; Sume does not run that model, but the Timeline fit modes give a reframe that never cuts anything out.

The four fit modes

Each video[] slot in Timeline 1.0 has a fit of cover (the default), contain, stretch or blur. The default output is a 1080x1920 MP4, so a wide clip needs a decision.

The arithmetic

A 16:9 shot fitted by width inside 1080 px is 1080 wide and about 608 px tall, which is 32% of the 1920 px canvas height. The other 68% is the fill. With contain that area is empty; with blur it is a blurred copy of the shot.

So blur gives a small subject on a large canvas. For a close-up, the crop in video filter keeps the subject larger. For a wide product shot, blur keeps it all.

A one-slot render

The render needs a spine; use silence mode if the clip carries its own message, and the clip's own length as the duration. Replace a.mp4 with your clip, imported to media.sume.com.

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: blur-fill-001" \
  -d '{"audio":{"mode":"silence","duration_seconds":8},
       "video":[{"source_url":"https://media.sume.com/artifacts/artf_demo/a.mp4",
                 "start":0,"duration":8,"fit":"blur"}]}'

When to choose which

Pick blur for wide establishing shots, landscapes, product lineups and two-person frames. Pick a crop for a single subject you can place with one x value. Pick cover when losing the sides is fine. Do not pick stretch unless the distortion is the point.

Compose is a different tool: timeline compose puts one still and one video in the same frame, with its own fit options (cover, contain, stretch, and blur is not a compose fit).

The render costs $0.10 per ceil(output minute). A clip of 8 seconds is $0.10. There is no provider inference in the step.

Compare the three outputs

Run the same 8-second wide clip three ways and look at the results on a phone. A crop with video filter (x 0.3418, width 0.3164) keeps the center and enlarges it. A cover slot does a similar center crop without a separate filter job. A blur slot keeps everything and shrinks the shot to about 608 px of height in the 1920 px canvas.

The crop path costs the extra $0.02 filter job on top of the render. The cover and blur paths cost only the render, $0.10 per ceil(output minute).

Mixed sources in one cut

fit is per slot, so one render can mix a blur-filled wide shot with a cover-fitted close-up. The default output is 1080x1920, so a vertical AI clip passes through at full size, while 16:9 clips need a choice. Keep one rule per scene to avoid the look of a different fit at every cut.

Limits to remember

Timeline output edges are even integers from 256 to 2160, so 1080x1920 is inside the range. The render is a re-encode, so run it once at the end rather than stacking renders. A clip with its own burned-in captions near the edges is a reason to prefer blur over cover, because cover cuts the sides.