Proof frame for a 1080x1920 export: video frames PNG at 1920

To proof a 1080x1920 export before upload, extract one or two lossless stills with video frames: at: [1, 12], format: "png". Frames keep the source size when you leave max_edge out, so a 1080x1920 export comes back at 1080x1920. Setting max_edge: 1920 is the same size for a vertical clip and makes the intent explicit. The job returns durable image artifacts, never modifies the source, and fails a single frame softly (a null url) without failing the job.

What to look at in the still

A proof frame answers questions a probe cannot: whether the crop cut off a face, whether burned-in captions are inside the frame, and whether text is legible at full size.

The request

Submit returns 202 always; frames does not support mode: "sync". Poll GET /v1/video-frames/:id until resource_status is ready, then read frames[{t,url,width,height}]. Billing is by the worker's compute, with the reserve capped at the hold, so a two-frame proof is a small job.

Import the clip first with POST /v1/media-imports, and send an Idempotency-Key on writes.

curl -X POST https://api.sume.com/v1/video-frames \
  -H "Authorization: Bearer $SUME_API_KEY" \
  -H "Content-Type: application/json" \
  -H "Idempotency-Key: proof-001" \
  -d '{
    "video_url": "https://media.sume.com/artifacts/artf_demo/export.mp4",
    "at": [1, 12],
    "format": "png",
    "max_edge": 1920
  }'

Common failures

• frame_time_out_of_range: an at value is at or past the duration; the error reports the probed duration.
• duration_out_of_range: the source is longer than 300 seconds; cut it with video trim first.
• A 400 for sending at[] and fps together, or more than 24 values.
• For probe facts or a transcript instead, use video inspect.

A three-frame routine

For a 42.5 second export, three frames cover most failures: one near the start, one in the middle where captions are densest, and one just before the end. The last frame must be before the duration, so use the duration minus a small margin, not the duration itself.

What to compare

Open each still at full size beside the platform's overlay. Look for three things: any caption word that touches a screen edge, any face or product that the crop clipped, and any text inside the picture that is too small to read on a phone. If you find one, fix it at the earliest step that caused it: the crop numbers in video filter, the placement in captions, or the fit in Timeline. Then repeat the proof on the new file.

Because frames are durable media.sume.com artifacts, you can keep a proof beside each final file as a record of what you checked. A null frame url means that one instant could not be extracted; the job still succeeds, so inspect the result before assuming all frames exist.

The same routine works for any vertical export from this series, whether it came from a crop, a trim or a Timeline render. It is cheap to run, it does not touch the file, and it finds the mistakes that matter most before the audience does: a clipped face, a caption that runs off the edge, or a frame that is the wrong shape.