MP4 and MOV metadata in a generated clip

MP4 and MOV metadata in a generated clip?

Two 64 by 64 clips written here with ffmpeg and libx264, each 0.200 seconds, stored a title, an encoder or software string, and a comment, and the MP4 and MOV top-level boxes were ftyp, free or wide, mdat, and moov.

Last updated 2026-10-21

Last checked 2026-10-22

MP4

1798 bytes. Major brand isom. Compatible brands isom, iso2, avc1, mp41. Top-level boxes ftyp, free, mdat, moov. Duration 0.200 s. Resolution 64×64. Track handler video. Video codec avc1. Title CPKGapTitle20261021. Encoder Lavf60.16.100. Comment CPKGapComment20261021.

MOV

1763 bytes. Major brand qt. Compatible brands qt. Top-level boxes ftyp, wide, mdat, moov. Duration 0.200 s. Resolution 64×64. Codec avc1. Title CPKGapMovTitle20261021. Software Lavf60.16.100. Description and comment both CPKGapMovComment20261021.

How to read that

The labels come from the site’s ISO-BMFF walker: ftyp, mvhd, tkhd, stsd, and udta/ilst. Encoder is the ©too value, software is ©swr, title is ©nam, and comment is ©cmt. A creation time in the movie header can remain after a cleaner neutralizes user-data boxes. That limit is already stated on the verify page.

Open a real file in the video metadata viewer. These two files only show what that walker printed for generated samples.

Sources

ExifTool download page, for the separate local tool that reads many more container tags

Last checked 2026-10-22.

Questions

Are these camera files?

No. Both are lavfi color frames encoded with libx264. The title and comment were passed as ffmpeg metadata, not typed on a phone.

Why do description and comment match on the MOV?

The site inspector maps both the description and comment labels from the comment string it found. The file was given one comment, CPKGapMovComment20261021, and both labels printed that value.

MP4 and MOV metadata in a generated clip