iPhone video checker

What the checker reads

A video file keeps its description in one place, an index called moov, and its pictures and sound in another, mdat. The checker reads only the index. It moves past the pictures without reading them, so a 3 GB video costs the page a few kilobytes of reads, and the file stays where it is.

From the index it shows the size, length, container (QuickTime or MP4), codec, resolution, frame rate and average bitrate. It also shows the dynamic range, the recording date and time, the place, the camera and the sound track. Missing fields say “Not in this file”.

Why the picker converts the video

When a web page asks for a video, Photos hands it a copy. By default the Format is Automatic, which gives the page the most compatible version: an H.264 file that plays in any browser. The copy is not the video you recorded.

We tested this in the iOS 27 Simulator with a 5-second HEVC clip, tagged with a location and a recording date. The page received a 9,506,554-byte H.264 copy, against the 7,624,391-byte HEVC original. The copy had no location and no creation date. Photos kept the original untouched, but the page had a different file.

	Format: Automatic (default)	Format: Current
What the page gets	An H.264 copy, 9,506,554 bytes	The original, 7,624,391 bytes
Codec	H.264	HEVC
Recorded date and location	Removed	Kept

What HDR and Dolby Vision mean in the file

SDR is the ordinary dynamic range that most screens show. HDR keeps brighter highlights and more detail in them. iPhone records HDR in two forms the checker names:

• HDR (HLG): the picture also looks right on an SDR screen, so it can be shown on both.
• HDR10 (PQ): an HDR curve that needs an HDR screen.

Dolby Vision adds metadata for each scene on top of a base picture. iPhone’s Dolby Vision is profile 8.4: an HLG base layer that any HDR screen can play, plus the Dolby data. In the file it is marked by a Dolby Vision configuration record, which Apple describes in TN3145. The checker reads that record and shows the profile as “Dolby Vision profile 8.4”.

Dates, time zones and places

Photos stores the time the phone recorded, with its offset from UTC, as creationdate. The checker shows that wall-clock time with its offset, so 18:30 at UTC+03:00 stays 18:30. The movie’s own header stores a time too, but in UTC. When a file has no recording date, the checker shows that time and says it is UTC.

The place is stored as ISO 6709 text: latitude, longitude and, if present, altitude. Some tools write it under ©xyz, a name ExifTool uses. The checker reads that as a fallback. It shows the coordinates as text and loads no map.

What the estimate means

The ring is the file’s size. The mint arc is what Emptie could free at the Preset you choose. High Quality keeps 4K, Balanced makes 1080p at medium, and Max Savings makes 1080p at high. The bitrates behind them are provisional and can change as Emptie is tuned.

For a 5-minute 4K Dolby Vision clip of 2.18 GB, Balanced gives about 307 MB by the estimate. Emptie’s measured copy was 323 MB, so the estimate runs about 5% low. Treat it as about, not exact. A video whose copy would save under 20% is Already efficient, and Emptie leaves it alone.

Compare with the copy

Choose an original and its compressed copy to check four things: length, recorded date, location and HDR. Emptie makes the same kind of check before it replaces an original. It carries over the date, location, Favorite, Hidden and your own albums. Face tags, Memories and Shared Album links cannot be carried over.

Your file stays on your device

The page makes no request while you use it. It sets no cookie and stores nothing. It reads the file in slices, so the file never has to fit in memory. The file name and coordinates appear on this page only.