Lemon8 video length and ratio: 60 s, 3:4, prepared on Sume

Lemon8 supports videos up to 60 seconds and favors a 3:4 aspect ratio, according to its own how-to page. To get a longer 16:9 recording there, cut it to 60 seconds or less, crop it to 3:4 and conform it to 1080x1440. Sume does both with two hosted ffmpeg jobs: video trim, then video filter.

What Lemon8 says

The page is short. It gives three numbers and is silent on file size and file format, so do not assume any limit beyond these.

The crop math for a 16:9 source

Sume's video filter takes a crop as fractions of the source frame. A 1920x1080 clip needs a 3:4 window at full height: 1080 x 3/4 = 810 px wide. As fractions that is width 0.421875, height 1, and a centered x of (1 - 0.421875) / 2 = 0.2890625. The compiler rounds to even values for yuv420p, so expect 810x1080 out.

If your subject is not centered, move x anywhere from 0 to 0.578125 (x plus width must stay at or under 1).

Step 1: trim to 60 seconds

Video trim cuts one Sume-hosted clip to a new MP4 and leaves the source alone. Send start and exactly one of end or duration. The default precision is exact, a frame-accurate re-encode, and the optional output object conforms width, height and fps in the same job. Import the clip first, because the API does not fetch open-internet URLs. The documented public rate is $0.02 per job (check GET /v1/catalog for the live price). Source up to 1800 s, output up to 900 s.

curl -X POST https://api.sume.com/v1/video-trim \
  -H "Authorization: Bearer $SUME_API_KEY" \
  -H "Content-Type: application/json" \
  -H "Idempotency-Key: lemon8-trim-001" \
  -d '{
    "video_url": "https://media.sume.com/artifacts/artf_demo/talk.mp4",
    "start": 0,
    "duration": 60
  }'

Step 2: crop to 3:4

Feed the trimmed MP4 (the video_url in the trim result) to video filter with one crop op. Run POST /v1/video-filter/check first: it is unbilled and returns diagnostics instead of a 400. The filter's source ceiling is 300 s, which a 60 s clip clears.

Then conform to 1080x1440 with a second video trim call that sends start 0, the same duration and an output of width 1080, height 1440 (exact precision only), or scale inside the filter program if you prefer one job.

curl -X POST https://api.sume.com/v1/video-filter \
  -H "Authorization: Bearer $SUME_API_KEY" \
  -H "Content-Type: application/json" \
  -H "Idempotency-Key: lemon8-crop-001" \
  -d '{
    "video_url": "https://media.sume.com/artifacts/artf_demo/trimmed.mp4",
    "ops": [{ "op": "crop", "x": 0.2890625, "y": 0, "width": 0.421875, "height": 1 }]
  }'

Check before you post

Poll GET /v1/jobs/:id/result for each job and read duration_seconds and any warnings. If the result carries trim_clamped_to_source, your source was shorter than the end you asked for. Because Lemon8 gives no file-size or format rule, the only things to verify are the two it names: length at or under 60 s, and a 3:4 frame.

Limits

Cropping removes the sides of a landscape frame, so captions or logos near the edges are cut. For a source that is already vertical, see the 3:4 crop post linked below. Details of both jobs are in the video trim and video filter docs.