Workflow
Prepare an iPhone MOV or HEVC recording for upload
Short answer
iPhone recordings are MOV containers usually holding HEVC. Both are accepted in some places and rejected in others, which is why the same file works on one platform and fails on another.
The decision that matters: Container or codec. MOV is widely accepted, so a rejection is more often the HEVC inside it than the wrapper. Converting the container alone will not fix a codec rejection.
Step by step
Check what you actually have
Read the dimensions, ratio, duration and size off the file before deciding anything. Most bad exports come from assuming the source rather than looking at it.
Check whether the destination documents MOV
Several platforms accept MOV directly, in which case converting is unnecessary work and an extra generation of quality loss.
Convert to MP4 if you need the safest option
MP4 with H.264 is the most widely documented combination. This re-encodes, so keep the original.
Check the size
iPhone 4K recordings are large; confirm the file is under the destination limit before uploading.
Limits to know
- The browser cannot read the codec inside your file - it reads the container and dimensions only. Codec is inferred from where the file came from, not measured.
- Converting is lossy. Archive the original iPhone file.
Run the whole workflow in one place
Koldflux takes one source through checking, reframing, captions and export, and gives you a pack per platform.
Reviewed October 5, 2026 by the Koldflux team against the platform limits used by the linked tools.