YouTube thumbnail 2 MB on mobile vs 50 MB on desktop: video still

A YouTube custom thumbnail for a video or Short can be up to 2 MB when uploaded on mobile and up to 50 MB on desktop, as JPG or PNG. To extract a still from a Sume clip, use video-frames with format: jpeg for a small file, and check its size against the 2 MB mobile cap.

Which limit applies where?

The limit depends on the device you upload from.

How do I get a still?

The default jpeg is lossy and light, while png is for lossless inspection. max_edge can shrink the long edge between 16 and 2160 pixels.

curl -X POST https://api.sume.com/v1/video-frames \
  -H "Authorization: Bearer $SUME_API_KEY" \
  -H "Content-Type: application/json" \
  -H "Idempotency-Key: yt-thumb-001" \
  -d '{"video_url": "https://media.sume.com/artifacts/artf_demo/talk.mp4", "at": [4.2], "format": "jpeg", "max_edge": 1280}'

What should I avoid?

Do not pick a frame by guess. Extract a few candidates with at (up to 24 per call), look at them, and keep one. YouTube also recommends 16:9 for videos, so a vertical frame needs a plan, which the related posts cover.