YouTube 48fps upload: keep the frame rate, conform to 24/25/30/60

Yes, YouTube takes a 48 fps upload. Its help page says content should be encoded and uploaded at the frame rate it was recorded, and lists 24, 25, 30, 48, 50 and 60 as common rates. Sume's frame-rate conform is narrower: output.fps accepts only 24, 25, 30 or 60, so 48 and 50 can be inherited from the source but not chosen.

Facts are from YouTube Help and Sume's video trim and Timeline docs, read 2026-10-01.

What does YouTube say about frame rate?

The page's rule is to keep the recorded rate. It adds that other frame rates are also acceptable, and that interlaced content should be deinterlaced first. It does not ask you to convert 48 or 50 fps footage to a standard rate.

So the safest default is no conversion at all. Re-timing footage to a different rate is a creative choice, not a YouTube requirement.

Which frame rates can Sume output?

The same four values appear on both surfaces that conform frame rate.

How do I keep 48 or 50 fps through a Sume edit?

Omit fps. For trim, the docs say to omit it to inherit the source; for Timeline, omitting it matches the sources. Trimming a 48 fps clip without an output block therefore leaves the rate alone.

Note that output on trim works only with precision: "exact". Pairing it with keyframe is refused with video_trim_output_requires_exact.

What if I need a rate Sume does not list?

Then the conform has to happen outside Sume, or you pick the nearest listed value and accept the change in motion. Moving 50 fps to 25 or 60 changes how motion looks; check a sample before publishing a batch.

For the general question of changing frame rate with ffmpeg flags, see ffmpeg change frame rate and how its flags map to API fields.

Does trim have size limits that matter here?

The source must be on media.sume.com and at most 1800 seconds; there is no open-internet fetch, so import the file first. The trimmed output is capped at 900 seconds.