HEVC phone clip for LinkedIn: exact trim re-encodes, keyframe copies

For a LinkedIn ad, use precision: "exact" on Sume's video trim, which re-encodes to H.264, and avoid keyframe, which copies the stream and keeps whatever codec the source had. LinkedIn lists H.264 or VP8 as the codec and MP4 as the only format (LinkedIn page, read 2026-10-09). The trim docs say exact is a frame-accurate re-encode with libx264 and yuv420p, and keyframe is a stream copy (Sume docs, read 2026-10-09).

Why a phone clip is the risky case

Phones can record in HEVC (H.265). If the source is HEVC and you trim with keyframe, the output is a stream copy, so it is still HEVC in an MP4. LinkedIn's page does not list H.265, so that file is outside its codec list. Pinterest's page, by contrast, lists H.264 or H.265, so the same stream-copied file would be inside Pinterest's list. I cannot tell you the codec of your source; you need to probe it.

What to send

Send video_url, start, and one of end or duration, with an Idempotency-Key. Leave precision out, because exact is the default. The job costs $0.02 and the result gives duration_seconds and actual_start_seconds. Audio is kept by default and exact precision remuxes it as AAC, which matches the AAC or MPEG4 audio line on LinkedIn's page.

If you need to conform size or rate in the same job, output takes width, height and fps (24, 25, 30 or 60), and works only with exact. Sending output with keyframe is refused with video_trim_output_requires_exact. Choose fps 24 or 25 to stay under LinkedIn's 30 FPS limit.

Checking the source first

Video inspect returns probe facts for a hosted clip, and with frames: false it returns only the probe. Read the codec there if you plan to use keyframe for speed. If you do not want to look, use exact; it is the default for a reason, and a re-encode costs the same $0.02. The only reason to pick keyframe is to avoid re-encoding a clip that is already in the target codec.

A failure you might see

The related case of a ProRes upload that fails processing is covered in the ProRes post. The fix is the same: probe, then trim with exact. For a wider table of what each platform lists, see the four-platform codec table.