Add motion blur to video: the tmix frame-blend filter API

Sume has no dedicated motion-blur filter, but the video filter allowlist includes tmix and tblend, which blend a frame with its neighbors. Put tmix=frames=3 in the filtergraph of POST /v1/video-filter for a blur-like smear; the encode is listed at $0.02 per job.

Higgsfield's changelog (Cinema Studio 4.0, Aug 12, 2026, read 2026-10-01) mentions camera presets and a rebuilt 5-lens system. Those shape the shot at generation time. A post-pass like this one is a file edit, not a lens.

What does frame blending do?

Averaging neighboring frames smears anything that moved between them. It looks like blur, but it is a ghost of the previous positions, not the continuous streak a long shutter gives. On a 24 fps source with fast action the ghosts are far apart, so you may see doubled edges instead of a smooth trail.

How do I run it?

Check first; it is free. The output keeps the source frame rate, geometry and audio unless the program changes them.

curl -X POST https://api.sume.com/v1/video-filter/check \
  -H "Authorization: Bearer $SUME_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "video_url": "https://media.sume.com/artifacts/artf_demo/action.mp4",
    "filtergraph": "tmix=frames=3"
  }'

What are the limits?

The source must be 300 seconds or shorter. The filter cannot see motion direction, so it blurs static and moving areas by the same rule: a static background stays sharp because it is the same in each frame, and moving subjects smear. If a clip is 24 fps, the docs' Timeline note on frame rates in 24 vs 30 fps explains how rates are matched later.

Should I try it on a short clip first?

Yes. Trim a few seconds with video trim, run the check, then one encode, and compare against the source. It costs the per-job rate and tells you whether the look works before you spend on the full clip.