Premiere 26.5 4:2:2 10-bit HEVC: probe a file before an exact trim

Premiere 26.5 adds hardware-accelerated decoding of 4:2:2 10-bit AVC and HEVC in MXF on NVIDIA Blackwell GPUs. That is about editing speed on your own machine. If you send the same footage to Sume, two facts matter: an exact trim re-encodes to libx264 in yuv420p, and the docs do not promise that every HEVC or MXF source is accepted. The safe move is to probe the file, then trim.

What the trim output looks like

With precision: exact (the default) the worker re-encodes the cut to libx264 with yuv420p. That means 4:2:2 chroma and 10-bit depth are not preserved, and the docs do not describe tone mapping for HDR sources. With precision: keyframe the worker stream-copies, which keeps the source codec but can only start at a keyframe, so the actual start can differ from the one you asked for. The result reports actual_start_seconds and precision so you can see what happened.

Probe first

POST /v1/video-inspect with frames: false is a probe-only call, and the probe-only call is free. It reports the codec and stream details, which tells you whether to proceed, convert elsewhere, or cut a mezzanine copy in your own tools first. Run it before spending anything on trim or captions.

curl -X POST https://api.sume.com/v1/video-inspect \
  -H "Authorization: Bearer $SUME_API_KEY" \
  -H "Content-Type: application/json" \
  -H "Idempotency-Key: probe-hevc-001" \
  -d '{"video_url":"https://media.sume.com/artifacts/artf_demo/talk.mp4","frames":false}'

Honest limits

• The docs do not confirm which HEVC profiles or MXF wrappers trim accepts; the probe call is how you find out for a given file.
• Do not use an exact trim as a grading master: it writes an 8-bit-class yuv420p file.
• Adobe's post says nothing about Sume, and Sume does not claim GPU decoding.